International journals

@Article{BeinBierDocq24,
  author = {Michel Beine and Michel Bierlaire and Fr\'ed\'eric Docquier},
  title = {New York, Abu Dhabi, London or Stay at Home? Using a Cross-Nested Logit Model to Identify Complex Substitution Patterns in Migration},
  journal = {Journal of Economic Geography},
  year = {to appear},
  note = {Accepted on Jan 16, 2024}}}

This paper reviews the literature on disaggregated travel demand models from a choice perspective, focusing on activity-based models (ABMs) and synthetic population generators as example approaches to capture these choice dimensions. We discuss the links between these models and elaborate on their integration, emphasizing how advanced population synthesis can address gaps in ABMs. The importance of incorporating multi-person and multi-period contexts to more accurately represent travel behavior is highlighted. Further advancements aimed at improving the practical application of these models are also discussed.

@Article{RezKucBie24,
  author = {Negar Rezvany and Marija Kukic and Michel Bierlaire},
  title = {A review of activity-based disaggregate travel demand models},
  journal = {Findings},
  year = {2024},
  note = {Accepted on Nov 01, 2024}}}

@Article{KukiXinlBier24,
  author = {Marija Kukic and Xinling Li and Michel Bierlaire},
  title = {One-step Gibbs sampling for the generation of synthetic households},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2024},
  volume = {166},
  number = {104770},
  DOI = {10.1016/j.trc.2024.104770},
  note = {Accepted on Jul 14, 2024}}}

The functional design of a decision support system for a state-of-the-art vehicle sharing system (VSS) inevitably includes the selection or definition of methodologies for planning and managing the observed VSS. In this paper, our focus is on an innovative VSS that utilizes light electric vehicles. Our goal is to specify the functions of a comprehensive decision making solution for such a VSS through a qualitative and systematic literature and system analysis. To achieve this goal, we rely on the holistic VSS management framework developed in our previous research. As a result of our study, we identify possible solution methodologies or algorithms for implementing functions of the designed decision making solution, and propose the necessary adjustments for their application in the case of light electric vehicles, or note any research gap. With these findings, we provide justified guidance to practitioners in creating these solutions, with the aim of reducing development time.

@Article{ObreAtacBier24,
  author = {Nikola Obrenovic and Selin Atac and Michel Bierlaire},
  title = {Light electric vehicle sharing systems: Functional design of a comprehensive decision making solution},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2024},
  volume = {182},
  number = {104043},
  DOI = {10.1016/j.tra.2024.104043},
  note = {Accepted on Mar 09, 2024}}}

In the context of discrete choice modeling, the extraction of potential behavioral insights from large datasets is often limited by the poor scalability of maximum likelihood estimation. This paper proposes a simple and fast dataset-reduction method that is specifically designed to preserve the richness of observations originally present in a dataset, while reducing the computational complexity of the estimation process. Our approach, called LSH-DR, leverages locality-sensitive hashing to create homogeneous clusters, from which representative observations are then sampled and weighted. We demonstrate the efficacy of our approach by applying it on a real-world mode choice dataset: the obtained results show that the samples generated by LSH-DR allow for substantial savings in estimation time while preserving estimation efficiency at little cost.

@Article{OrteLappBier2024,
  author = {Nicola Ortelli and Matthieu {de Lapparent} and Michel Bierlaire},
  title = {Resampling Estimation of Discrete Choice Models},
  journal = {Journal of Choice Modelling},
  year = {2024},
  volume = {50},
  number = {100467},
  DOI = {10.1016/j.jocm.2023.100467},
  note = {Accepted on Dec 20, 2023}}}

Understanding mobility dynamics and their influence on epidemic spread is crucial for effective management strategies, a concept that, despite its importance, has received limited integration in traditional epidemiological models. This study introduces a novel decision support tool that integrates an activity-based model for mobility dynamics with a multi-group compartmental SIRD (Susceptible–Infected–Recovered–Dead) model for infection transmission. The tool consists of a multi-objective optimization framework that evaluates the trade-offs between public health and economic factors in socioeconomic segments. Our findings show that policies targeted at specific demographic groups significantly improve the efficacy of interventions. The framework provides policymakers with a collection of optimized and customized strategies through a user-friendly dashboard, using a multi-objective modeling approach. This visualization compares potential outcomes along the Pareto frontier, helping to select balanced and effective policies. The proposed model offers a significant step forward in epidemic management, providing a robust platform for data-driven decision making in crisis scenarios.

@Article{CortKrueBier24,
  author = {Cloe {Cortes Balcells} and Rico Krueger and Michel Bierlaire},
  title = {Multi-objective Optimization of Activity-Travel Policies for Epidemic Control: Balancing Health and Economic Outcomes on Socio-Economic Segments},
  journal = {Transportation Research Interdisciplinary Perspectives},
  year = {2024},
  volume = {27},
  number = {101183},
  DOI = {10.1016/j.trip.2024.101183},
  note = {Accepted on Jul 30, 2024}}}

Various interactions, time arrangements, and constraints exist for individuals scheduling their day as a member of a household, which affect their in-home as well as out-of-home activity schedule. However, the existing activity-based models are mostly based on the individual decision-making process, which are limited in their demonstration of behaviour. We simulate multiple intra-household interaction dimensions within the same framework and capture the coordination of the activity scheduling decisions among all household members. Our approach adopts the Optimisation-based Activity Scheduling Integrating Simultaneous choice dimensions (OASIS) framework, which is at the level of isolated individuals and focuses on out-of-home activity schedules. We jointly simulate in- and out-of-home activities and incorporate interactions into the framework. Our framework contributes to the state-of-the-art in activity-based modelling by explicitly capturing multiple interactions within the same model, such as the allocation of the private vehicle to household members, dividing household maintenance responsibilities, escorting, joint activity participation, and sharing rides. We operationalise the model using time-use-survey data from the United Kingdom. The simulation results demon- strate the ability of the framework to capture complex intra-household interactions. We then demonstrate how these interactions can cause individuals to deviate from their schedules planned in isolation. This is a general framework applicable to different household compositions and available resources.

@Article{RezBieHil23,
  author = {Negar Rezvany and Michel Bierlaire and Tim Hillel},
  title = {Simulating intra-household interactions for in- and out-of-home activity scheduling},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2023},
  volume = {157},
  number = {104362},
  DOI = {10.1016/j.trc.2023.104362},
  note = {Accepted on Sep 26, 2023}}}

Ride-sourcing services offered by companies like Uber and Didi have grown rapidly in the last decade. Understanding the demand for these services is essential for planning and managing modern transportation systems. Existing studies develop statistical models for ride-sourcing demand estimation at an aggregate level due to limited data availability. These models lack foundations in microeconomic theory, ignore competition of ride-sourcing with other travel modes, and cannot be seamlessly integrated into existing individual-level (disaggregate) activity-based models to evaluate system-level impacts of ride-sourcing services. In this paper, we present and apply an approach for estimating ride-sourcing demand at a disaggregate level using discrete choice models and multiple data sources. We first construct a sample of trip-based mode choices in Chicago, USA by enriching household travel survey with publicly available ride-sourcing and taxi trip records. We then formulate a multivariate extreme value-based discrete choice model with sampling and endogeneity corrections to account for the construction of the estimation sample from multiple data sources and endogeneity biases arising from supply-side constraints and surge pricing mechanisms in ride-sourcing systems. Our analysis of the constructed dataset reveals insights into the influence of various socio-economic, land use and built environment features on ride-sourcing demand. We also derive elasticities of ride-sourcing demand relative to travel cost and time. Finally, we illustrate how the developed model can be employed to quantify the welfare implications of ride-sourcing policies and regulations such as terminating certain types of services and introducing ride-sourcing taxes.

@Article{KrueBierBans23,
  author = {Rico Krueger and Michel Bierlaire and Prateek Bansal},
  title = {A data fusion approach for ride-sourcing demand estimation: A discrete choice model with sampling and endogeneity corrections },
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2023},
  volume = {152},
  number = {104180},
  DOI = {10.1016/j.trc.2023.104180},
  note = {Accepted on May 17, 2023}}}

Understanding user’s perception of service variability is essential to discern their overall perception of any type of (transport) service. We study the perception of waiting time variability for ride-hailing services. We carried out a stated preference survey in August 2021, yielding 936 valid responses. The respondents were faced with static pre-trip information on the expected waiting time, followed by the actually experienced waiting time for their selected alternative. We analyse this data by means of an instance-based learning (IBL) approach to evaluate how individuals respond to service performance variation and how this impacts their future decisions. Different novel specifications of memory fading, captured by the IBL approach, are tested to uncover which describes the user behaviour best. Additionally, existing and new specification of inertia (habit) are tested. Our model outcomes reveal that the perception of unexpected waiting time is within the expected range of 2–3 times the value-of-time. Travellers seem to place a higher reward on an early departure compared to a penalty for a late departure of equal magnitude. A cancelled service, after having made a booking, results in significant disutility for the passenger and a strong motivation to shift to a different provider. Considering memory decay, our results show that the most recent experience is by far the most relevant for the next decision, with memories fading quickly in importance. The role of inertia seems to gain importance with each additional consecutive choice for the same option, but then resetting back to zero following a shift in behaviour.

@Article{GerzCatsVanOHoogBierHoog23,
  author = {Nejc Gerzinic and Oded Cats and Niels {van Oort} and Sascha Hoogendoorn-Lanser and Michel Bierlaire and Serge Hoogendoorn},
  title = {An instance-based learning approach for evaluating the perception of ride-hailing waiting time variability},
  journal = {Travel Behaviour and Society},
  year = {2023},
  volume = {33},
  number = {100616},
  DOI = {10.1016/j.tbs.2023.100616},
  note = {Accepted on Feb 04, 2023}}}

@Article{KrueBierGasoBans22,
  author = {Rico Krueger and Michel Bierlaire and Thomas Gasos and Prateek Bansal},
  title = {Robust discrete choice models with t-distributed kernel errors},
  journal = {Statistics and Computing},
  year = {2023},
  volume = {33},
  number = {2},
  DOI = {10.1007/s11222-022-10182-3},
  note = {Accepted on Nov 12, 2022}}}

@Article{PougHillBier23,
  author = {Janody Pougala and Tim Hillel and Michel Bierlaire},
  title = {OASIS: Optimisation-based Activity Scheduling with Integrated Simultaneous choice dimensions},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2023},
  volume = {155},
  DOI = {10.1016/j.trc.2023.104291

}}}

@Article{JiangChenPasch,
  author = {Jiang Like and Chen Haibo and Evangelos Paschalidis},
  title = {Diffusion of connected and autonomous vehicles concerning mode choice, policy interventions and sustainability impacts: A system dynamics modelling study},
  journal = {Transport  Policy},
  year = {2023},
  volume = {141},
  DOI = {https://doi.org/10.1016/j.tranpol.2023.07.029}}}

@Article{MastPaschNikifBas,
  author = {Chrysanthi Mastora and Evangelos Paschalidis and Andreas Nikiforiadis and Socrates Basbas},
  title = {Pedestrian Crossings as a Means of Reducing Conflicts between

Cyclists and Pedestrians in Shared Spaces},
  journal = {Sustainability},
  year = {2023},
  volume = {15},
  number = {12},
  DOI = {https://doi.org/10.3390/su15129377}}}

We propose a new modelling approach for daily activity scheduling which integrates the different daily scheduling choice dimensions (activity participation, location, schedule, duration and transportation mode) into a single optimisation problem. The fundamental behavioural principle behind our approach is that individuals schedule their day to maximise their overall derived utility from the activities they complete, according to their individual needs, constraints, and preferences. By combining mul- tiple choices into a single optimisation problem, our framework is able to capture the complex trade-offs between scheduling decisions for multiple activities. These trade-offs could include how spending longer in one activity will reduce the time- availability for other activities or how the order of activities determines the travel- times. The implemented framework takes as input a set of considered activities, with associated locations and travel modes, and uses these to produce empirical distri- butions of individual schedules from which different daily schedules can be drawn. The model is illustrated using historic trip diary data from the Swiss Mobility and Transport Microcensus. The results demonstrate the ability of the proposed frame- work to generate complex and realistic distributions of starting time and duration for different activities within the tight time constraints. The generated schedules are then compared to the aggregate distributions from the historical data to demonstrate the feasibility and flexibility of our approach.

@Article{PougHillBier22,
  author = {Janody Pougala and Tim Hillel and Michel Bierlaire},
  title = {Capturing trade-offs between daily scheduling choices},
  journal = {Journal of Choice Modelling},
  year = {2022},
  volume = {43},
  number = {100354},
  DOI = {10.1016/j.jocm.2022.100354},
  note = {Accepted on Mar 19, 2022}}}

Advanced driver assistance systems such as adaptive cruise control (ACC) and lane keeping system (LKS) potentially contribute to reducing crash rates and traffic congestion. On-road studies based on early ACC systems operational at medium–high speeds only have shown that the system reduces the proportion of short time gaps when activated. Despite the effects on driver behaviour, most mathematical models assessing the impact of ACC and LKS systems on crash rates and traffic congestion are not based on empirical findings. This study examines the factors that influence changes in the longitudinal vehicle control when driving with ACC and LKS. The data were collected in a naturalistic driving experiment with full-range ACC and LKS and two different vehicle brands (BMW and Tesla) in the Netherlands. To capture changes that are relevant for traffic safety, speeding and a time gap shorter than one second were investigated. The factors influencing speeding and short time gaps were analysed using statistical tests and logistic regression models with random effects, that allow to control for the impact of different explanatory variables and correlations between repeated 10-s intervals over time. The findings revealed that, overall, drivers were less likely to speed and they were also less likely to have a time gap shorter than one second in the experimental condition with the ACC and the LKS than in the baseline condition in manual driving. Drivers were likely to speed in the following 10-s interval when the current speed was close to the speed limit, and/or when the next speed limit was lower than the current speed limit, and/or when the acceleration was high. Drivers were likely to have a short time gap in the following 10-s interval when approaching a slower leader, and/or when the current time gap was short and/or when the acceleration was high. Controlled for these main factors, drivers were less likely to speed and to have a short time gap when the ACC and the LKS were active. However, drivers were more likely to speed when overruling the ACC by pressing the gas pedal. When the systems were active, one vehicle brand showed a smaller probability of a short time gap than the other brand, suggesting differences in ACC system settings between brands. In addition, the speeding probability increased while the probability of a short time gap decreased over time during the trip after the activation of the systems. Although further studies including a larger sample of participants and a wider range of traffic situations are needed, the results are useful to the design of automated vehicles that prevent speeding and short time gaps, and to the implementation of traffic simulations that evaluate the impact of ACC and LKS on crash rates and traffic congestion according to realistic on-road data.

@Article{VaroMonsHogeChriVanNMart22,
  author = {Silvia Varotto and Celina Mons and Jeroen Hogema and Michiel Christoph and Nicole {Van Nes} and Marieke Martens},
  title = {Do adaptive cruise control and lane keeping systems make the longitudinal vehicle control safer?},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2022},
  volume = {141},
  pages = {103756},
  DOI = {10.1016/j.trc.2022.103756},
  note = {Accepted on Jun 04, 2022}}}

Urban mobility services face the challenge of planning their operations efficiently while complying with user preferences. In this paper, we introduce a new mathematical model called a choice-driven dial-a-ride problem (CD-DARP) which is a generalization of the dynamic DARP where passenger behavior is integrated in the operational planning using choice models and assortment optimization. We look at two types of mobility services, private and shared. Our problem extends the dynamic DARP by (i) changing its objective function to profit maximization, where both cost and revenue are variables, and (ii) incorporating assortment optimization with routing decisions in a dynamic setting. We propose a pricing scheme based on a choice model designed to offer service alternatives at the time a customer makes a request. We introduce a tailored algorithm to efficiently solve the dynamic CD-DARP. Computational results indicate that our proposed approach outperforms dynamic DARP in terms of reducing routing costs and improving the number of customers served.

@Article{SharAtasBenABierMakn22,
  author = {Shadi {Sharif Azadeh} and Bilge Atasoy and Moshe Ben-Akiva and Michel Bierlaire and Yousef Maknoon},
  title = {Choice-Driven Dial-A-Ride Problem for Demand Responsive Mobility Service},
  journal = {Transportation Research Part B: Methodological},
  year = {2022},
  volume = {161},
  pages = {128-149},
  DOI = {10.1016/j.trb.2022.04.008},
  note = {Accepted on Apr 29, 2022}}}

Vulnerable road users (VRUs) constitute an increasing proportion of the annual road fatalities across Europe. One of the crash types involved in these fatalities are blind spot crashes between trucks and bicyclists. Despite the presence of mandatory blind spot mirrors, truck drivers are often reported to have overlooked the presence of a bicyclist. This raises the question if and when truck drivers check their blind spot mirrors for the presence of bicyclists, and which factors contribute to such glance behavior. The current study presents the results of an analysis of naturalistic glance behavior by 39 truck drivers in 1,903 right-turning maneuvers at urban intersections, where in each maneuver there was a chance of crossing the path of a bicyclist. The descriptive analysis revealed that most often truck drivers did not cast a glance upon their blind spot mirrors as recommended by the examination guidelines. Furthermore, a choice model was developed with the main factors that have an impact on glance behavior. Drivers were more likely to glance with a priority regulation that allowed conflicts, with lower speed limits, with zebra crossings, without cyclist facilities, without a lead vehicle making the same maneuver, in presence of VRUs, without adverse sight conditions, in lower age groups, without certain non-driving related activities, when driving a truck with more direct vision on VRUs, and without a camera providing a view on the blind spot, and with less time between a standstill and starting the maneuver. Three factors did not significantly improve the choice model and were therefore left out, despite showing significant effects in bivariate tests: intersection layout (e.g., three vs. four legs), presence of advanced stopping lanes, and visual obstruction. Implications of the choice model are discussed for driver education (in terms of timely glances, reducing inattention, and hazard anticipation) and vehicle design (in terms of direct vision).

@Article{JansVaro2022,
  author = {Silvia Varotto and Reinier Jansen},
  title = {Caught in the blind spot of a truck: A choice model on driver glance behavior towards cyclists at intersections},
  journal = {Accident Analysis and Prevention},
  year = {2022},
  volume = {174},
  pages = {106759},
  DOI = {10.1016/j.aap.2022.106759},
  note = {Accepted on Jun 15, 2022}}}

@Article{PachGendSharBier22,
  author = {Meritxell Pacheco and Bernard Gendron and Shadi {Sharif Azadeh} and Michel Bierlaire},
  title = {A Lagrangian decomposition scheme for choice-based optimization},
  journal = {Computers \& Operations Research},
  year = {2022},
  volume = {148},
  pages = {105985},
  DOI = {10.1016/j.cor.2022.105985},
  note = {Accepted on Jul 29, 2022}}}

This paper presents a novel activity-based demand model that combines an optimisation framework for continuous temporal scheduling decisions (i.e. activity timings and durations) with traditional discrete choice models for non-temporal choice dimensions (i.e. activity participation, number and type of tours, and destinations). The central idea of our approach is that individuals resolve temporal scheduling conflicts that arise from overlapping activities, e.g. needing to work and desiring to shop at the same time, in order to maximise their daily utility. Flexibility parameters capture behavioural preferences that penalise deviations from desired timings. This framework has three advantages over existing activity-based modelling approaches: (i) the time conflicts between different temporal scheduling decisions including the activity sequence are treated jointly; (ii) flexibility parameters follow a utility maximisation approach; and (iii) the framework can be used to estimate and simulate a city-scale case study in reasonable time. We introduce an estimation routine that allows flexibility parameters to be estimated using real-world observations as well as a simulation routine to efficiently resolve temporal conflicts using an optimisation model. The framework is applied to the full-time workers of a synthetic population for the city of Lausanne, Switzerland. We validate the model results against reported schedules. The results demonstrate the capabilities of our approach to reproduce empirical observations in a real-world case study.

@Article{MansHaerHillPougKrueBier22,
  author = {Patrick Manser and Tom Haering and Tim Hillel and Janody Pougala and Rico Krueger and Michel Bierlaire},
  title = {Estimating flexibility preferences to resolve temporal scheduling conflicts in activity-based modelling},
  journal = {Transportation},
  year = {2022},
  DOI = {10.1007/s11116-022-10330-8},
  note = {Accepted on Aug 22, 2022}}}

@Article{BansDuaKrueGrah2021,
  author = {Prateek Bansal and Rubal Dua and Rico Krueger and Daniel Graham},
  title = {Fuel Economy Valuation and Preferences of Indian Two-wheeler Buyers},
  journal = {Journal of Cleaner Production},
  year = {2021},
  volume = {294},
  pages = {126328},
  DOI = {10.1016/j.jclepro.2021.126328},
  note = {Accepted on Feb 07, 2021}}}

@Article{MolyScarBier20,
  author = {Nicholas Molyneaux and Riccardo Scarinci and Michel Bierlaire},
  title = {Design and analysis of control strategies for pedestrian flows},
  journal = {Transportation},
  year = {2021},
  volume = {48},
  pages = {1767-1807},
  DOI = {10.1007/s11116-020-10111-1},
  note = {Accepted on Apr 18, 2020}}}

Machine Learning (ML) approaches are increasingly being investigated as an alternative to Random Utility Models (RUMs) for modelling passenger mode choice. These approaches have the potential to provide valuable insights into choice modelling research questions. However, the research and the methodologies used are fragmented. Whilst systematic reviews on RUMs for mode choice prediction have long existed and the methods have been well scrutinised for mode choice prediction, the same is not true for ML models. To address this need, this paper conducts a systematic review of ML methodologies for modelling passenger mode choice. The review analyses the methodologies employed within each study to (a) establish the state-of-research frameworks for ML mode choice modelling and (b) identify and quantify the prevalence of methodological limitations in previous studies. A comprehensive search methodology across the three largest online publication databases is used to identify 574 unique records. These are screened for relevance, leaving 70 peer-reviewed articles containing 73 primary studies for data extraction. The studies are reviewed in detail to extract 17 attributes covering five research questions, concerning (i) classification techniques, (ii) datasets, (iii) performance estimation, (iv) hyper-parameter selection, and (v) model analysis. The review identifies ten common methodological limitations. Five are determined to be methodological pitfalls, which are likely to introduce bias in the estimation of model performance. The remaining five are identified as areas for improvement, which may limit the achieved performance of the models considered. A further six general limitations are identified, which highlight gaps in knowledge for future work.

@Article{HillBierElshJin21,
  author = {Tim Hillel and Michel Bierlaire and Mohammed Elshafie and Ying Jin},
  title = {A systematic review of machine learning classification methodologies for modelling passenger mode choice},
  journal = {Journal of Choice Modelling},
  year = {2021},
  volume = {38},
  number = {100221},
  DOI = {10.1016/j.jocm.2020.100221},
  note = {Accepted on May 10, 2020}}}

The emergence of Big Data has enabled new research perspectives in the discrete choice community. While the techniques to estimate Machine Learning models on a massive amount of data are well established, these have not yet been fully explored for the estimation of statistical Discrete Choice Models based on the random utility framework. In this article, we provide new ways of dealing with large datasets in the context of Discrete Choice Models. We achieve this by proposing new efficient stochastic optimization algorithms and extensively testing them alongside existing approaches. We develop these algorithms based on three main contributions: the use of a stochastic Hessian, the modification of the batch size, and a change of optimization algorithm depending on the batch size. A comprehensive experimental comparison of fifteen optimization algorithms is conducted across ten benchmark Discrete Choice Model cases. The results indicate that the HAMABS algorithm, a hybrid adaptive batch size stochastic method, is the best performing algorithm across the optimization benchmarks. This algorithm speeds up the optimization time by a factor of 23 on the largest model compared to existing algorithms used in practice. The integration of the new algorithms in Discrete Choice Models estimation software will significantly reduce the time required for model estimation and therefore enable researchers and practitioners to explore new approaches for the specification of choice models.

@Article{LedeLurkHillBier21,
  author = {Gael Lederrey and Virginie Lurkin and Tim Hillel and Michel Bierlaire},
  title = {Estimation of Discrete Choice Models with Hybrid Stochastic Adaptive Batch Size Algorithms},
  journal = {Journal of Choice Modelling},
  year = {2021},
  volume = {38},
  number = {100226},
  DOI = {10.1016/j.jocm.2020.100226},
  note = {Accepted on May 20, 2020}}}

@Article{BansKrueGrah20,
  author = {Prateek Bansal and Rico Krueger and Daniel Graham},
  title = {Fast Bayesian estimation of spatial count data models},
  journal = {Computational Statistics \& Data Analysis},
  year = {2021},
  volume = {157},
  pages = {107152},
  DOI = {10.1016/j.csda.2020.107152},
  note = {Accepted on Dec 01, 2020}}}

This paper considers vessel scheduling with pilotage and tugging constraints in berthing operations with channel restrictions at seaports. To our knowledge, pilotage and tugging requirements have not been simultaneously considered in the literature. This work proposes a mixed integer programming (MIP) formulation and an exact solution approach, based on constraint separation techniques, to solve the problem. The solution approach is initiated with a heuristic that runs in polynomial time. The approach then adds separation cuts to a relaxed version of the MIP formulation and updates the bounds until an optimal solution has been found. A real case and simulated realistic cases are used to compare the proposed model against the first-come first-serve (FCFS) policy that is traditionally used in vessel scheduling. The results show that significant improvements can be obtained, especially during congestion periods. Finally, a computational study demonstrates that the proposed solution approach is capable of solving real-size cases in a reasonable time.

@Article{AbouDiabBier21,
  author = {Omar {Abou Kasm} and Ali Diabat and Michel Bierlaire},
  title = {Vessel scheduling with pilotage and tugging considerations},
  journal = {Transportation Research Part E: Logistics and Transportation Review},
  year = {2021},
  volume = {148},
  DOI = {10.1016/j.tre.2021.102231},
  note = {Accepted on Jan 06, 2021}}}

This paper presents a novel deep learning-based travel behaviour choice model. Our proposed Residual Logit (ResLogit) model formulation seamlessly integrates a Deep Neural Network (DNN) architecture into a multinomial logit model. Recently, DNN models such as the Multi-layer Perceptron (MLP) and the Recurrent Neural Network (RNN) have shown remarkable success in modelling complex and noisy behavioural data. However, econometric studies have argued that machine learning techniques are a `black-box' and difficult to interpret for use in the choice analysis. We develop a data-driven choice model that extends the systematic utility function to incorporate non-linear cross-effects using a series of residual layers and using skipped connections to handle model identifiability in estimating a large number of parameters. The model structure accounts for cross-effects and choice heterogeneity arising from substitution, interactions with non-chosen alternatives and other effects in a non-linear manner. We describe the formulation, model estimation, interpretability and examine the relative performance and econometric implications of our proposed model. We present an illustrative example of the model on a classic red/blue bus choice scenario example. For a real-world application, we use a travel mode choice dataset to analyze the model characteristics compared to traditional neural networks and Logit formulations. Our findings show that our ResLogit approach significantly outperforms MLP models while providing similar interpretability as a Multinomial Logit model.

@Article{WongFaro21,
  author = {Melvin Wong and Bilal Farooq},
  title = {ResLogit: A residual neural network logit model for data-driven choice modelling},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2021},
  volume = {126},
  pages = {103050},
  DOI = {10.1016/j.trc.2021.103050},
  note = {Accepted on Feb 15, 2021}}}

@Article{PachSharBierGend21,
  author = {Meritxell Pacheco and Michel Bierlaire and Bernard Gendron and Shadi {Sharif Azadeh}},
  title = {Integrating advanced discrete choice models in mixed integer linear optimization },
  journal = {Transportation Research Part B: Methodological},
  year = {2021},
  volume = {146},
  pages = {26-49},
  DOI = {10.1016/j.trb.2021.02.003},
  note = {Accepted on Feb 09, 2021}}}

Given the high levels of congestion that many commuters in the United States experience, the urban air mobility community has been exploring the potential of using a new class of electric vertical takeoff and landing (eVTOL) aircraft for commuters. To date, only a few studies have been conducted that compare how potential air taxi demand across cities varies. This study calculates a measure of air taxi demand for commuters for the 40 most populous combined statistical areas (CSAs) in the U.S. by using: (1) cell phone data to identify regular commuters in cities, (2) census data to associate household income characteristics with commuters, and (3) a mode choice model calibrated from a stated preference survey to predict the number of commuters that would use an air taxi. Air taxi commuter demand is concentrated in a handful of CSAs; the CSAs for New York City, Los Angeles, and Washington, D.C., generate 33 percent of the overall air taxi demand. Results are sensitive to location of existing vertiports, existing ground infrastructure and congestion levels on competing modes, and current commute patterns. A resultant set of online maps of potential air taxi routes allows readers to visualize how air taxi commuter routes differ across CSAs. Results will be of value both to aircraft manufacturers seeking to design air taxi vehicles to serve different cities as well as city planners for identifying where investments in port infrastructure may be needed to support a commuter air taxi service.

@Article{HaanGarrMarzRoyBier21,
  author = {Julien Haan and Laurie Garrow and Aude Marzuoli and Satadru Roy and Michel Bierlaire},
  title = {Are Commuter Air Taxis Coming to Your City? A Ranking of 40 Cities in the United States},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2021},
  volume = {132},
  pages = {103392},
  DOI = {10.1016/j.trc.2021.103392},
  note = {Accepted on Sep 11, 2021}}}

@Article{KrueBierDaziRashBans,
  author = {Rico Krueger and Michel Bierlaire and Ricardo Daziano and Taha Rashidi and Prateek Bansal},
  title = {Evaluating the predictive abilities of mixed logit models with unobserved inter- and intra-individual heterogeneity},
  journal = {Journal of Choice Modelling},
  year = {2021},
  volume = {41},
  pages = {100323},
  DOI = {10.1016/j.jocm.2021.100323},
  note = {Accepted on Sep 09, 2021}}}

@Article{BindMaknSharBier,
  author = {Stefan Binder and Yousef Maknoon and Shadi {Sharif Azadeh} and Michel Bierlaire},
  title = {Passenger-Centric Timetable Rescheduling: A User Equilibrium Approach},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2021},
  volume = {132},
  pages = {103368},
  DOI = {10.1016/j.trc.2021.103368},
  note = {Accepted on Aug 26, 2021}}}

@Article{BortLurkBier21b,
  author = {Stefano Bortolomiol and Virginie Lurkin and Michel Bierlaire},
  title = {Price-based regulation of oligopolistic markets under discrete choice models of demand },
  journal = {Transportation},
  year = {2021},
  DOI = {https://doi.org/10.1007/s11116-021-10217-0},
  note = {Accepted on Jul 23, 2021}}}

Although different vehicle sharing systems (VSSs) use different vehicle types, the management challenges and optimization problems to be solved are similar or even the same. This observation led us to create a generalized and holistic VSS management framework, which aims to be applicable to the system using any vehicle type. The framework components, their mutual relationships, and framework tasks have been identified through a thorough and systematic literature review. Furthermore, the literature is positioned in the line with the framework. Finally, the framework and systematic literature review allowed us to identify gaps in the literature, and interesting research avenues.

@Article{AtacObreBier21,
  author = {Selin Atac and Nikola Obrenovic and Michel Bierlaire},
  title = {Vehicle Sharing Systems: A Review and a Holistic Management Framework},
  journal = {EURO Journal on Transportation and Logistics},
  year = {2021},
  volume = {10},
  number = {100033},
  DOI = {10.1016/j.ejtl.2021.100033},
  note = {Accepted on Feb 24, 2021}}}

Determining appropriate utility specifications for discrete choice models is time-consuming and prone to errors. As the number of possible functions exponentially grows with the vari- ables under consideration, analysts need to spend increasing amounts of time on searching for good specifications through trial-and-error and expert knowledge. This paper proposes a data-driven algorithm that aims at assisting modelers in their search. Our approach trans- lates the task into a multi-objective combinatorial optimization problem and makes use of a variant of the variable neighborhood search algorithm to generate solutions. We apply the algorithm to a real mode choice dataset as a proof of concept. The results demonstrate its ability to generate high-quality specifications in reasonable amounts of time.

@Article{OrteHillCamadeLaBier21,
  author = {Nicola Ortelli and Tim Hillel and Francisco Pereira and Matthieu {de Lapparent} and Michel Bierlaire},
  title = {Assisted Specification of Discrete Choice Models},
  journal = {Journal of Choice Modelling},
  year = {2021},
  volume = {39},
  number = {100285},
  DOI = {10.1016/j.jocm.2021.100285},
  note = {Accepted on Mar 16, 2021}}}

@Article{BortLurkBier21,
  author = {Stefano Bortolomiol and Virginie Lurkin and Michel Bierlaire},
  title = {A simulation-based heuristic to find approximate equilibria with disaggregate demand models},
  journal = {Transportation Science},
  year = {2021},
  volume = {55},
  number = {5},
  pages = {1025-1045},
  DOI = {https://doi.org/10.1287/trsc.2021.1071},
  note = {Accepted on Apr 16, 2021}}}

@Article{MoreBaboBierMare19,
  author = {Stefano Moret and Fr\'ed\'eric Babonneau and Michel Bierlaire and Fran\c{c}ois Mar\'echal},
  title = {Overcapacity in European power systems: analysis and robust optimization approach},
  journal = {Applied energy},
  year = {2020},
  volume = {259},
  number = {113970},
  DOI = {10.1016/j.apenergy.2019.113970},
  note = {Accepted on Oct 08, 2019}}}

@Article{MoreBaboMareBier19,
  author = {Stefano Moret and Fr\'ed\'eric Babonneau and Michel Bierlaire and Fran\c{c}ois Mar\'echal},
  title = {Decision support for strategic energy planning: a complete robust optimization framework},
  journal = {European Journal of Operational Research},
  year = {2020},
  volume = {280},
  pages = {539-554},
  DOI = {10.1016/j.ejor.2019.06.015},
  note = {Accepted on Apr 28, 2019}}}

@Article{MarkBierCordMaknVaro19,
  author = {Iliya Markov and Michel Bierlaire and Jean-Fran\c{c}ois Cordeau and Yousef Maknoon and Sacha Varone},
  title = {Waste Collection Inventory Routing with Non-stationary Stochastic Demands},
  journal = {Computers \& Operations Research},
  year = {2020},
  volume = {113},
  number = {104798},
  DOI = {10.1016/j.cor.2019.104798},
  note = {Accepted on Sep 03, 2019}}}

@Article{BansKrueBierDaziRash19,
  author = {Prateek Bansal and Rico Krueger and Michel Bierlaire and Ricardo Daziano and Taha Rashidi},
  title = {Bayesian Estimation of Mixed Multinomial Logit Models: Advances and Simulation-Based Evaluations},
  journal = {Transportation Research Part B: Methodological},
  year = {2020},
  volume = {131},
  pages = {124-142},
  DOI = {10.1016/j.trb.2019.12.001},
  note = {Accepted on Dec 02, 2019}}}

@Article{KimTakBierYeo20,
  author = {Jeongyun Kim and Sehyun Tak and Michel Bierlaire and Hwasoo Yeo},
  title = {Trajectory Data Analysis on the Spatial and Temporal Influence of Pedestrian Flow on Path Planning Decision},
  journal = {Sustainability},
  year = {2020},
  volume = {12},
  number = {10419},
  pages = {1-16},
  DOI = {10.3390/su122410419},
  note = {Accepted on Dec 11, 2020}}}

@Article{KrueRashVij2020,
  author = {Rico Krueger and Taha Rashidi and Akshay Vij},
  title = {A Dirichlet process mixture model of discrete choice: Comparisons and a case study on preferences for shared automated vehicles},
  journal = {Journal of Choice Modelling},
  year = {2020},
  volume = {36},
  pages = {105623},
  note = {Accepted on May 27, 2020}}}

@Article{KrueBanBud2020,
  author = {Rico Krueger and Prateek Bansal and Prasad Buddhavarapu},
  title = {A New Spatial Count Data Model with Bayesian Additive Regression Trees for Accident Hot Spot Identification},
  journal = {Accident Analysis and Prevention},
  year = {2020},
  volume = {144},
  pages = {105623},
  DOI = {10.1016/j.aap.2020.105623},
  note = {Accepted on May 28, 2020}}}

@Article{MuelGuerObreBier20,
  author = {Florian Mueller and Markus Guerster and Nikola Obrenovic and Michel Bierlaire},
  title = {Can regional railway become emission-free with recently announced vehicles? - A case study of Bavaria},
  journal = {European Journal of Transport and Infrastructure Research},
  year = {2020},
  volume = {20},
  number = {4},
  pages = {286-305},
  DOI = {10.18757/ejtir.2020.20.4.5439},
  note = {Accepted on Sep 01, 2020}}}

@Article{RodrOrteBierPere20,
  author = {Filipe Rodrigues and Nicola Ortelli and Michel Bierlaire and Francisco Pereira},
  title = {Bayesian Automatic Relevance Determination for Utility Function Specification in Discrete Choice Models},
  journal = {IEEE Transactions on Intelligent Transportation Systems},
  year = {2020},
  DOI = {10.1109/TITS.2020.3031965},
  note = {Accepted on Oct 14, 2020}}}

This paper focuses on the application of tractable route choice models and presents a set of methods for deriving relevant disaggregate and aggregate route choice indicators, namely link and route flows. Tractability is achieved at the disaggregate level by the recursive logit model and at the aggregate level by the mental representation item (MRI) approach. These two approaches are analyzed here, and extensions of the MRI approach are presented. The analysis elaborates on the features of each model and allows to draw insights into the use of a specific model, depending on the needs of the application and the data availability. The performance of the two models is tested on real data. The results demonstrate the validity of the MRI model that is intended for aggregate analysis.

@Article{KazBierLap_2017_TRANSPORTATION,
  author = {Evanthia Kazagli and Michel Bierlaire and Matthieu {de Lapparent}},
  title = {Operational route choice methodologies for practical applications},
  journal = {Transportation},
  year = {2020},
  volume = {47},
  pages = {43-74},
  DOI = {10.1007/s11116-017-9849-0},
  note = {Accepted on Dec 21, 2017}}}

@Article{HurtBierMart17,
  author = {Ricardo Hurtubia and Francesco Martinez and Michel Bierlaire},
  title = {A quasi-equilibrium approach for market clearing in land use microsimulations},
  journal = {Environment and Planning B},
  year = {2019},
  volume = {46},
  number = {3},
  pages = {445{\textendash}468},
  DOI = {10.1177/2399808317719071},
  note = {Accepted on Jun 12, 2017}}}

Independent modeling of various modules of an information system (IS), and consequently database subschemas, may result in formal or semantic conflicts between the modules being modeled. Such conflicts may cause collisions between the integrated database schema of a whole IS and the modeled subschemas. In our previous work, we have proposed criteria and algorithms for identifying and resolving such conflicts so as to provide a consolidation of database subschemas with the integrated database schema with respect to various database concepts, such as domains, relation schemes, primary key constraints and referential integrity constraints. In this paper, we propose a new approach and algorithms for identifying conflicts and testing consolidation of subschemas with the integrated database schema against check constraints. The proposed approach is based on satisfiability modulo theory (SMT) solvers. Hereby, we propose the integration of SMT solvers into our MDSD tool, aimed at supporting a database schema integration process.

@Article{ObrLukRis2019,
  author = {Nikola Obrenovic and Ivan Lukovic and Sonja Ristic},
  title = {Consolidation of database check constraints},
  journal = {Software \& Systems Modeling},
  year = {2019},
  volume = {18},
  number = {3},
  pages = {2111-2135},
  DOI = {10.1007/s10270-017-0637-2},
  note = {Accepted on Nov 24, 2017}}}

@Article{ScarZanaBier19,
  author = {Riccardo Scarinci and Alessandro Zanarini and Michel Bierlaire},
  title = {Electrification of urban mobility: the case of catenary-free buses},
  journal = {Transport  Policy},
  year = {2019},
  volume = {80},
  pages = {39-48},
  DOI = {10.1016/j.tranpol.2019.05.006},
  note = {Accepted on May 04, 2019}}}

@Article{NikBieLapSca_2018_TS,
  author = {Marija Nikolic and Michel Bierlaire and Matthieu {de Lapparent} and Riccardo Scarinci},
  title = {Multi-class speed-density relationship for pedestrian traffic},
  journal = {Transportation Science},
  year = {2019},
  volume = {53},
  number = {3},
  pages = {642-664},
  DOI = {10.1287/trsc.2018.0849},
  note = {Accepted on Apr 30, 2018}}}

@Article{SharBierMakn,
  author = {Shadi {Sharif Azadeh} and Michel Bierlaire and Yousef Maknoon},
  title = {A Two-Stage Route Optimization Algorithm for Light Aircraft Transport Systems},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2019},
  volume = {100},
  pages = {259-273},
  DOI = {10.1016/j.trc.2019.01.028},
  note = {Accepted on Jan 28, 2019}}}

@Article{HerrLurkGarrClarBier19,
  author = {Jordan Herring and Virginie Lurkin and Laurie Garrow and John-Paul Clarke and Michel Bierlaire},
  title = {Airline customers{\textquoteright} connection time preferences in domestic U.S. markets},
  journal = {Journal of Air Transport Management},
  year = {2019},
  volume = {79},
  number = {101688},
  DOI = {10.1016/j.jairtraman.2019.101688},
  note = {Accepted on Jun 28, 2019}}}

This paper deals with a main limitation of Markovian traffic assignment (MTA) models: when the network includes cyclic structures and the link costs are small enough, the fact that the MTA models assign traffic flows to all feasible paths causes computational challenges. This study addresses this issue by proposing a method of restricting path set based on the concept of choice-based prism. To achieve a prism-based path set, a novel network description and the constraints are introduced. These are flexible and compatible with the MTA operation, meaning that our method does not extinguish the mathematical and computational advantages of the MTA models. Our network description allows the expected minimum cost to take a value specific for each state, or a pair of node and choice-stage. This enables us to perform traffic assignment with a simple solution procedure, regardless of parameter setting or network structure. The numerical experiments show that our method solves the computational challenges of the MTA models and that the incorporation of the prism constraints does not increase computational effort required, or rather, it is computationally efficient even when considering the correlation among path utilities.

@Article{OyaHat19,
  author = {Yuki Oyama and Eiji Hato},
  title = {Prism-based path set restriction for solving Markovian traffic assignment problem},
  journal = {Transportation Research Part B: Methodological},
  year = {2019},
  volume = {122},
  pages = {528-546},
  DOI = {10.1016/j.trb.2019.02.002},
  note = {Accepted on Feb 09, 2019}}}

@Article{LuGarHinNewSc18,
  author = {Virginie Lurkin and Laurie Garrow and Matthew Higgins and Jeffrey Newman and Michael Schyns},
  title = {Modeling Competition among Airline Itineraries},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2018},
  volume = {113},
  pages = {157-172},
  note = {Accepted on Apr 03, 2018}}}

@Article{NikBie17_DataDrivenDiscretization,
  author = {Marija Nikolic and Michel Bierlaire},
  title = {Data-driven spatio-temporal discretization for pedestrian flow characterization},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2018},
  volume = {94},
  pages = {185-202},
  DOI = {10.1016/j.trc.2017.08.026},
  note = {Accepted on Aug 30, 2017}}}

@Article{MarkBierCordMaknVaro2017,
  author = {Iliya Markov and Michel Bierlaire and Jean-Fran\c{c}ois Cordeau and Yousef Maknoon and Sacha Varone},
  title = {A Unified Framework for Rich Routing Problems with Stochastic Demands},
  journal = {Transportation Research Part B: Methodological},
  year = {2018},
  volume = {114},
  pages = {213-240},
  DOI = {10.1016/j.trb.2018.05.015},
  note = {Accepted on May 24, 2018}}}

@Article{RoShMaDeBi18,
  author = {Tom\'a\v{s} Robenek and Shadi {Sharif Azadeh} and Yousef Maknoon and Matthieu {de Lapparent} and Michel Bierlaire},
  title = {Train Timetable Design Under Elastic Passenger Demand},
  journal = {Transportation Research Part B: Methodological},
  year = {2018},
  volume = {111},
  pages = {19-38},
  DOI = {10.1016/j.trb.2018.03.002},
  note = {Accepted on Mar 01, 2018}}}

@Article{FerAntDeLapBier17,
  author = {Anna Fernandez-Antolin and Matthieu {de Lapparent} and Michel Bierlaire},
  title = {Modeling purchases of new cars: an analysis of the 2014 French market},
  journal = {Theory and Decision},
  year = {2018},
  volume = {84},
  number = {2},
  pages = {277-303},
  DOI = {10.1007/s11238-017-9631-y},
  note = {Accepted on Sep 23, 2017}}}

Passive monitoring with the Global Positioning System (GPS) is increasingly used to automatically monitor trip data. However, GPS tracking data includes measurement errors that depend on the monitoring device and network description in the model. In the case of urban pedestrian networks, such as city centers, the built environment of streets is often diverse, and this has a significant impact on the measurement. The errors cause the biased observations of route choices, and thus the parameter estimation results of route choice models are also biased. To deal with this problem of biased estimation, this study proposes a link-based route measurement model that sequentially infers links using decomposed sequences of data and estimates the link-specific variance of the GPS measurement error. We also incorporate a link-based route choice model as the prior to correct the measurement model by considering behavioral mechanism without path enumeration. Additionally, to remove the biases included in the prior information, this study proposes a structural estimation method in which the fixed point problem of behavioral parameter is solved by the iteration process. The performance of the proposed methods is examined both through a numerical example and a case study on a real pedestrian network. As the results, the methods refine the performance of the route measurement model, and the estimated parameters of a route choice model obtained by the structural estimation method are less biased and exhibit a different trend than those using the biased route choice observations. Also, the estimated variances of the GPS measurement errors are realistic.

@Article{OyaHat18,
  author = {Yuki Oyama and Eiji Hato},
  title = {Link-based measurement model to estimate route choice parameters in urban pedestrian networks},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2018},
  volume = {93},
  pages = {62-78},
  DOI = {10.1016/j.trc.2018.05.013},
  note = {Accepted on May 15, 2018}}}

@Article{CORMAKNOON(2),
  author = {Yousef Maknoon and Francois Soumis and Pierre Baptiste},
  title = {An integer programming approach to scheduling the transshipment of products at cross-docks in less-than-truckload industries},
  journal = {Computers \& Operations Research},
  year = {2017},
  volume = {82},
  pages = {167{\textendash}179},
  DOI = {10.1016/j.cor.2017.01.018},
  note = {Accepted on Jan 27, 2017}}}

@Article{UmanBierErer16,
  author = {Nitish Umang and Michel Bierlaire and Alan Erera},
  title = {Real-time management of berth allocation with stochastic arrival and handling times},
  journal = {Journal of Scheduling},
  year = {2017},
  volume = {20},
  number = {1},
  pages = {67-83},
  DOI = {10.1007/s10951-016-0480-2},
  note = {Accepted on Mar 23, 2016}}}

@Article{ChenBier17,
  author = {{Jiang Hang} Chen and Michel Bierlaire},
  title = {The study of the unidirectional quay crane scheduling problem: complexity and risk-aversion},
  journal = {European Journal of Operational Research},
  year = {2017},
  volume = {260},
  number = {2},
  pages = {613-624},
  DOI = {10.1016/j.ejor.2017.01.007}}}

@Article{HaenLamBierLedeNiko16,
  author = {Flurin H\"anseler and William Lam and Michel Bierlaire and Gael Lederrey and Marija Nikolic},
  title = {A dynamic network loading model for anisotropic and congested pedestrian flows},
  journal = {Transportation Research Part B: Methodological},
  year = {2017},
  volume = {95},
  pages = {149-168},
  DOI = {10.1016/j.trb.2016.10.017},
  note = {Accepted on Oct 31, 2016}}}

@Article{RobeSharMaknBier17,
  author = {Tom\'a\v{s} Robenek and Shadi {Sharif Azadeh} and Yousef Maknoon and Michel Bierlaire},
  title = {Hybrid Cyclicity: Combining The Benefits Of Cyclic And Non-Cyclic Timetables},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2017},
  volume = {75},
  pages = {228-253},
  DOI = {10.1016/j.trc.2016.12.015},
  note = {Accepted on Dec 19, 2016}}}

Moving walkways (MW) have been imagined as a possible means of transport since the late 19th century, and this system has fascinated urban planners and engineers ever since. Contrary to what has been imagined, moving walkways are only used in transportation hub corridors, and not as a main transport mode in city centers. Today however, MWs are receiving increasing attention as a possible solution to congestion and pollution, as well as a catalyst for soft mobility. This paper explores the role of moving walkways as a transport system, and it presents an optimized design of a network of MWs in a city center. We review historical MWs, current installations and future possibilities, using different perspectives, from geography to urban planning to transport engineering. We discuss the way in which MWs influence how people inhabit the urban space, and we review this system in the context of history of urban planning. Then, we describe a technological development called accelerating moving walkways (AMW), i.e. MWs able to reach a higher speed than traditional ones. We develop an optimization framework to design a network of AMWs, and we apply it to a real case study. The results of the network design are a reference useful to discuss the feasibility of the system starting from an engineering perspective. We conclude that the use of MWs can facilitate the flexibility and spontaneity typical of pedestrian movements, and this system could be integrated in the mix of urban transport modes in city centers.

@Article{ScaBahOurBie_2017,
  author = {Riccardo Scarinci and Farzaneh Bahrami and Andr\'e Ourednik and Michel Bierlaire},
  title = {An exploration of moving walkways as a transport system in urban centers},
  journal = {European Journal of Transport and Infrastructure Research},
  year = {2017},
  volume = {17},
  number = {2},
  pages = {191-206},
  DOI = {10.18757/ejtir.2017.17.2.3190},
  note = {Accepted on Jan 11, 2017}}}

@Article{HaenMolyBier16,
  author = {Flurin H\"anseler and Nicholas Molyneaux and Michel Bierlaire},
  title = {Estimation of pedestrian origin-destination demand in train stations},
  journal = {Transportation Science},
  year = {2017},
  volume = {51},
  number = {3},
  pages = {981-997},
  DOI = {10.1287/trsc.2016.0723},
  note = {Accepted on Jul 07, 2016}}}

We propose a novel approach to pedestrian flow characterization. The definitions of density, flow and velocity existing in the literature are extended through a data-driven spatio-temporal discretization framework. The framework is based on three-dimensional Voronoi diagrams. Synthetic data is used to empirically investigate the performance of the approach and to illustrate its advantages. Our approach outperforms the considered approaches from the literature in terms of the robustness with respect to the simulation noise and with respect to the sampling frequency. Additionally, the proposed approach is by design (i) independent from an arbitrarily chosen discretization; (ii) appropriate for the multidirectional composition of pedestrian traffic; (iii) able to reflect the heterogeneity of the pedestrian population; and (iv) applicable to pedestrian trajectories described either analytically or as a sample of points.

@Article{NikBier_ISTTT22,
  author = {Marija Nikolic and Michel Bierlaire},
  title = {Data-driven spatio-temporal discretization for pedestrian flow characterization},
  journal = {Transportation Research Procedia},
  year = {2017},
  volume = {23},
  pages = {188{\textendash}207},
  DOI = {10.1016/j.trpro.2017.05.012},
  note = {Accepted on Feb 16, 2017}}}

@Article{BindMaknBier17,
  author = {Stefan Binder and Yousef Maknoon and Michel Bierlaire},
  title = {The multi-objective railway timetable rescheduling problem},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2017},
  volume = {78},
  pages = {78-94},
  DOI = {10.1016/j.trc.2017.02.001},
  note = {Accepted on Feb 01, 2017}}}

@Article{LuGarHinNewSc17,
  author = {Virginie Lurkin and Laurie Garrow and Matthew Higgins and Jeffrey Newman and Michael Schyns},
  title = {Accounting for Price Endogeneity in Airline Itinerary Choice Models: An Application to Continental U.S. Markets},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2017},
  volume = {100},
  pages = {228-246},
  DOI = {10.1016/j.tra.2017.04.007},
  note = {Accepted on Apr 03, 2017}}}

Pollution, congestion and urbanistic considerations are leading to a change in the use of private vehicles in dense city centers. More frequently, the last-mile is covered with systems such as public transport, car sharing and bike sharing as well as an increase in walking and cycling. Following this trend, we assume a hypothetical scenario where the use of private cars is strongly limited in dense urban areas, and innovative transport modes must be used. This work investigates a futuristic system based on a network of accelerating moving walkways (AMW) to facilitate the movement of pedestrians in city centers where cars have been banned. Unlike constant speed moving walkways, AMWs can reach speeds of up to 15km/h thanks to an acceleration section. This paper presents a rigorous description of the system characteristics from a transportation point of view, develops a heuristic algorithm for the network design problem, and tests it on a real case study. Given a network of urban roads and an origin-destination demand, the optimization algorithm, which combines traffic assignment and supply modification, explores the trade-off curve between the total travel time and capital cost of the infrastructure. The results give practical insight on the possible dimensioning of the system, show the optimal network designs, and how these vary with a reduction of the available budget. This paper investigates for the first time the use of AMWs at a network scale, and provides results useful for analyzing the system feasibility. The results on travel time, investment budget and payback period indicates that AMWs could be an effective mode of transport in cities.

@Article{ScaMarBie_2017,
  author = {Riccardo Scarinci and Iliya Markov and Michel Bierlaire},
  title = {Network design of a transport system based on accelerating moving walkways},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2017},
  volume = {80},
  pages = {310{\textendash}328},
  DOI = {10.1016/j.trc.2017.04.016},
  note = {Accepted on Apr 19, 2017}}}

Greenhouse gas emissions related to energy production is the main cause of climate change. Transportation accounts for 30% of the total energy consumption, and a reduction in the energy used for mobility is necessary. The 2000-watt society is an environmental concept that fixes a sustainable limit to the energy consumption in different sectors, including mobility. This paper evaluates the energy consumption in several mobility scenarios, and it assesses whether the goal suggested by the 2000-watt society is achievable. We investigate the social characteristics and travel habits of the population living in a case study area. Then, we calculate the modal shift induced by transportation policies such as car-sharing, car-pooling and car-free district. We evaluate the resulting energy consumption, and we compare it with the 2000-watt society limit. We conclude that only a set of measures combining car usage reduction, increase in walking and cycling, and reduction in the total travel distance can achieve the needed energy reduction.

@Article{ScaRasBie_2017,
  author = {Riccardo Scarinci and Frederic Rast and Michel Bierlaire},
  title = {Needed reduction in mobility energy consumption to meet the goal of a 2000-watt society},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2017},
  volume = {101},
  pages = {133-148},
  DOI = {10.1016/j.tra.2017.05.010},
  note = {Accepted on May 03, 2017}}}

@Article{MoreCodiBierMare17,
  author = {Stefano Moret and Victor {Codina Girones} and Michel Bierlaire and Fran\c{c}ois Mar\'echal},
  title = {Characterization of input uncertainties in strategic energy planning models},
  journal = {Applied energy},
  year = {2017},
  volume = {202},
  pages = {597-617},
  DOI = {10.1016/j.apenergy.2017.05.106},
  note = {Accepted on May 13, 2017}}}

@Article{VaroGlerStatBierLong17,
  author = {Silvia Varotto and Aur\'elie Glerum and Amanda Stathopoulos and Michel Bierlaire and Giovanni Longo},
  title = {Mitigating the impact of errors in travel time reporting on mode choice modelling},
  journal = {Journal of Transport Geography},
  year = {2017},
  volume = {62},
  pages = {236-246},
  DOI = {10.1016/j.jtrangeo.2017.05.016},
  note = {Accepted on May 31, 2017}}}

@Article{ScaHegHey17,
  author = {Riccardo Scarinci and Andreas Hegyi and Benjamin Heydecker},
  title = {Definition of a Merging Assistant Strategy Using Intelligent Vehicles},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2017},
  volume = {82},
  pages = {161{\textendash}179},
  DOI = {10.1016/j.trc.2017.06.017},
  note = {Accepted on Jul 01, 2017}}}

@Article{BindMaknBier17a,
  author = {Stefan Binder and Yousef Maknoon and Michel Bierlaire},
  title = {Exogenous priority rules for the capacitated passenger assignment problem},
  journal = {Transportation Research Part B: Methodological},
  year = {2017},
  volume = {105},
  pages = {19-42},
  DOI = {10.1016/j.trb.2017.08.022},
  note = {Accepted on Aug 17, 2017}}}

Emerging sensing technologies such as probe vehicles equipped with Global Positioning System (GPS) devices on board provide us real-time vehicle trajectories. They are helpful for the understanding of the cases that are significant but difficult to observe because of the infrequency, such as gridlock networks. On the premise of this type of emerging technology, this paper propose a sequential route choice model that describes route choice behavior, both in ordinary networks, where drivers acquire spatial knowledge of networks through their experiences, and in extraordinary networks, which are situations that drivers rarely experience, and applicable to real-time traffic simulations. In extraordinary networks, drivers do not have any experience or appropriate information. In such a context, drivers have little spatial knowledge of networks and choose routes based on dynamic decision making, which is sequential and somewhat forward-looking. In order to model these decision-making dynamics, we propose a discounted recursive logit model, which is a sequential route choice model with the discount factor of expected future utility. Through illustrative examples, we show that the discount factor reflects drivers’ decision-making dynamics, and myopic decisions can confound the network congestion level. We also estimate the parameters of the proposed model using a probe taxis’ trajectory data collected on March 4, 2011 and on March 11, 2011, when the Great East Japan Earthquake occurred in the Tokyo Metropolitan area. The results show that the discount factor has a lower value in gridlock networks than in ordinary networks.

@Article{OyaHat17,
  author = {Yuki Oyama and Eiji Hato},
  title = {A discounted recursive logit model for dynamic gridlock network analysis},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2017},
  volume = {85},
  pages = {509-527},
  DOI = {10.1016/j.trc.2017.10.001},
  note = {Accepted on Oct 01, 2017}}}

@Article{NewLurGar17,
  author = {Jeffrey Newman and Virginie Lurkin and Laurie Garrow},
  title = {Computational Methods for Estimating Multinomial, Nested, and Cross-Nested Logit Models that Account for Semi-Aggregate Data},
  journal = {Journal of Choice Modelling},
  year = {2017},
  volume = {26},
  pages = {28-40},
  note = {Accepted on Nov 02, 2017}}}

@Article{MarkVaroBier16,
  author = {Iliya Markov and Sacha Varone and Michel Bierlaire},
  title = {Integrating a heterogeneous fixed fleet and a flexible assignment of destination depots in the waste collection VRP with intermediate facilities},
  journal = {Transportation Research Part B: Methodological},
  year = {2016},
  volume = {84},
  pages = {256-273},
  DOI = {10.1016/j.trb.2015.12.004}}}

Long-term planning for energy systems is often based on deterministic economic optimization and forecasts of fuel prices.When fuel price evolution is underestimated, the consequence is a low penetration of renewables and more efficient technologies in favour of fossil alternatives. This work aims at overcoming this issue by assessing the impact of uncertainty on energy planning decisions. A classification of uncertainty in energy systems decision-making is performed. Robust optimization is then applied to a Mixed-Integer Linear Programming problem, representing the typical trade-offs in energy planning. It is shown that in the uncertain domain investing in more efficient and cleaner technologies can be economically optimal.

@Article{MoreBierMare15,
  author = {Stefano Moret and Michel Bierlaire and Fran\c{c}ois Mar\'echal},
  title = {Robust optimization for strategic energy planning},
  journal = {Informatica},
  year = {2016},
  volume = {27},
  number = {3},
  pages = {625-648},
  DOI = {10.15388/Informatica.2016.103},
  note = {Accepted on Nov 25, 2015}}}

To tackle the challenges of the 21st century, future scientists and engineers have to understand the interplay between societal challenges and technical solutions as early as possible in their education. They also have to develop the communication and the teamwork skills required to be effective professionals. To address this issue, the Ecole Polytechnique Fédérale de Lausanne (EPFL) introduced a new Global Issues program to all 1800 first year engineering students. In this paper, we present this novel program and reflect on our experience. Our results suggest that student who showed positive attitude towards teamwork, benefited the most from the course and increase their perspectives on societal issues as measured by their moral reasoning after the course.

@Article{GlobalIssues16,
  author = {Adrian Holzer and Isabelle {Von\`eche Cardia} and Samuel Bendahan and Alexis Berne and Luca Bragazza and Antonin Danalet and Ambrogio Fasoli and J\'er\^ome Feige and Denis Gillet and Siara Isaac and Ingrid {Le Duc} and Delphine Preissmann and Roland Tormey},
  title = {Increasing the Perspectives of Engineering Undergraduates on Societal Issues through an Interdisciplinary Program},
  journal = {International Journal of Engineering Education},
  year = {2016},
  volume = {32},
  number = {2(A)},
  pages = {1-11},
  note = {Accepted on Jan 09, 2016}}}

Land Use and Transport Integrated models (LUTIs) are promising approaches for urban planning. There is large literature describing their technical architectures or using them in various scientific contexts. Yet little attention has been paid to expectations of practitioners (planners) and to the operational use of such models. The gap between lab application and operational use for planning practice is still to be filled. We shed light on what would make them definitely accepted and more used by planners to evaluate a range of urban and transport policies. In addition to literature review and our own experience dealing with urban planning agencies, we have interviewed different types of end users in France to identify their motivations and barriers to use LUTI models. The results show demand for a far more bottom-up oriented approach: the models should consider objectives and general needs of end users to live up to their expectations. Only a closer collaboration between modelers and end users, and more efforts to integrate modeling into urban planning, will make LUTIs considered as relevant approaches.

@Article{saujotetal2016,
  author = {Mathieu Saujot and Matthieu {de Lapparent} and Elise Arnaud and Emmanuel Prados},
  title = {Making land use {\textendash} Transport models operational tools for planning: From a top-down to an end-user approach},
  journal = {Transport  Policy},
  year = {2016},
  volume = {49},
  pages = {20-29},
  DOI = {10.1016/j.tranpol.2016.03.005},
  note = {Accepted on Mar 09, 2016}}}

@Article{JanuUrrudeWe16,
  author = {Tiago Januario and Sebastian Urrutia and Dominique {de Werra}},
  title = {Sports scheduling search space connectivity: A riffle shuffle driven approach},
  journal = {Discrete Applied Mathematics},
  year = {2016},
  volume = {211},
  pages = {113-120},
  DOI = {10.1016/j.dam.2016.04.018},
  note = {Accepted on Apr 18, 2016}}}

@Article{RobeMakAzaChenBier16,
  author = {Tom\'a\v{s} Robenek and Yousef Maknoon and Shadi {Sharif Azadeh} and {Jiang Hang} Chen and Michel Bierlaire},
  title = {Passenger Centric Train Timetabling Problem},
  journal = {Transportation Research Part B: Methodological},
  year = {2016},
  volume = {89},
  pages = {107-126},
  DOI = {10.1016/j.trb.2016.04.003},
  note = {Accepted on Apr 01, 2016}}}

Location-aware data collection technologies provide new insights about location choices. Only a few dynamic models of location choice exist in scientific literature. To our knowledge, none of them correct for serial correlation. In this paper, we model choice of catering locations on a campus using WiFi traces. We use the [Wooldridge, J. M. (2005). Simple solutions to the initial conditions problem in dynamic, nonlinear panel data models with unobserved heterogeneity, Journal of Applied Econometrics 20(1): 39-54.] correction method that deals with the initial values problem and related endogeneity bias in estimation. Cross-validation, price elasticity and simulation of a scenario predicting the opening of a new catering location are presented. Predicted market shares of the new catering location correspond to point-of-sale data of the first week of opening.

@Article{DaTideLaBi15_JCM,
  author = {Antonin Danalet and Lo{\"\i}c Tinguely and Matthieu {de Lapparent} and Michel Bierlaire},
  title = {Location choice with longitudinal WiFi data},
  journal = {Journal of Choice Modelling},
  year = {2016},
  volume = {18},
  pages = {1-17},
  DOI = {10.1016/j.jocm.2016.04.003},
  note = {Accepted on Apr 12, 2016}}}

@Article{FernGuevDeLaBier16,
  author = {Anna Fernandez-Antolin and Angelo Guevara-Cue and Matthieu {de Lapparent} and Michel Bierlaire},
  title = {Correcting for endogeneity due to omitted attitudes: Empirical assessment of a modified MIS method using RP mode choice data},
  journal = {Journal of Choice Modelling},
  year = {2016},
  volume = {20},
  pages = {1-15},
  DOI = {10.1016/j.jocm.2016.09.001},
  note = {Accepted on Sep 01, 2016}}}

@Article{CORMAKNOON,
  author = {Yousef Maknoon and Gilbert Laporte},
  title = {Vehicle routing with cross-dock selection},
  journal = {Computers \& Operations Research},
  year = {2016},
  volume = {77},
  pages = {254{\textendash}266},
  DOI = {10.1016/j.cor.2016.08.007},
  note = {Accepted on Aug 23, 2016}}}

We analyze individual travel discomfort-time tradeoffs in the Paris subway using stated choice experiments. The survey design allows to set up in a willingness-to-pay space to estimate the distributions of elasticities of values of travel time to crowd density and time multipliers. Several formulations of a generalized travel cost function are tested. Accounting for heterogeneity in preferences, the econometric models all take the form of an ordered probit with known bounds. We derive several estimates that could be used for fine-tuning of traffic simulation systems and more general transportation policy analysis.

@Article{lapkon2015,
  author = {Matthieu {de Lapparent} and Martin Koning},
  title = {Analyzing time sensitivity in the Paris subway: an interval data model approach},
  journal = {Transportation},
  year = {2016},
  volume = {43},
  number = {5},
  pages = {913-933},
  DOI = {10.1007/s11116-015-9629-7},
  note = {Accepted on Aug 01, 2016}}}

@Article{KazBierFlo_JoCM_2016,
  author = {Evanthia Kazagli and Michel Bierlaire and Gunnar Fl\"otter\"od},
  title = {Revisiting the Route Choice Problem: A Modeling Framework Based on Mental Representations},
  journal = {Journal of Choice Modelling},
  year = {2016},
  volume = {19},
  pages = {1-23},
  DOI = {10.1016/j.jocm.2016.06.001},
  note = {Accepted on Jun 07, 2016}}}

@Article{IJPECD,
  author = {Yousef Maknoon and Francois Soumis and Pierre Baptiste},
  title = {Optimizing transshipment workloads in less-than-truckload cross-docks},
  journal = {International Journal of Production Economics},
  year = {2016},
  volume = {179},
  pages = {90-100},
  DOI = {10.1016/j.ijpe.2016.05.015},
  note = {Accepted on May 17, 2016}}}

@Article{HaenBierScar16,
  author = {Flurin H\"anseler and Michel Bierlaire and Riccardo Scarinci},
  title = {Assessing the usage and level-of-service of pedestrian facilities in train stations: A Swiss case study},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2016},
  volume = {89},
  pages = {106-123},
  DOI = {10.1016/j.tra.2016.05.010},
  note = {Accepted on May 16, 2016}}}

@Article{NikBieFarLap_ProbabilisticSpeedDensity,
  author = {Marija Nikolic and Michel Bierlaire and Bilal Farooq and Matthieu {de Lapparent}},
  title = {Probabilistic speed-density relationship for pedestrian traffic},
  journal = {Transportation Research Part B: Methodological},
  year = {2016},
  volume = {89},
  pages = {58-81},
  DOI = {10.1016/j.trb.2016.04.002},
  note = {Accepted on Apr 02, 2016}}}

@Article{KumaBier13,
  author = {Prem Kumar and Michel Bierlaire},
  title = {Optimizing Fueling Decisions for Locomotives in Railroad Networks},
  journal = {Transportation Science},
  year = {2015},
  volume = {49},
  number = {1},
  pages = {149-159},
  DOI = {10.1287/trsc.2013.0479},
  note = {Accepted on Apr 01, 2013}}}

During the last 40 years, a large number of studies have analyzed car holding and use behavior. Most of these ignore the dynamics of household and driver needs that very likely drive such decisions. Our work builds up on a disaggregate (compensatory) approach using revealed choices to address these dynamics. We develop a dynamic discrete/continuous choice model of car holding duration for forward-looking agents. We estimate this model using French panel survey data. Our findings indicate that a household’s time preference is a crucial element in car use and holding decisions.

@Article{CERNILAP2015,
  author = {Giulia Cernicchiaro and Matthieu {de Lapparent}},
  title = {A dynamic discrete-continuous choice model for forward-looking agents owning one or more vehicles},
  journal = {Computational Economics},
  year = {2015},
  volume = {46},
  pages = {15-34},
  DOI = {10.1007/s10614-014-9449-4}}}

In revenue management, the profitability of the inventory and pricing decisions rests on the accuracy of demand forecasts. However, whenever a product is no longer available, true demand may differ from registered bookings, thus inducing a negative bias in the estimation figures, as well as an artificial increase in demand for substitute products. In order to address these issues, we propose an original Mixed Integer Nonlinear Program (MINLP) to estimate product utilities as well as capturing seasonal effects. This behavioral model solely rests on daily registered bookings and product availabilities. Its outputs are the product utilities and daily potential demands, together with the expected demand of each product within any given time interval. Those are obtained via a tailored algorithm that outperforms two well-known generic software for global optimization

@Article{ShaMarSav15,
  author = {Shadi {Sharif Azadeh} and Patrice Marcotte and Gilles Savard},
  title = { A Non-Parametric Approach to Demand Forecasting in Revenue Management},
  journal = {Computers \& Operations Research},
  year = {2015},
  volume = {12},
  number = {1},
  pages = {99-109},
  DOI = {10.1007/s10287-014-0204-z}}}

@Article{ScaHeyHeg15,
  author = {Riccardo Scarinci and Benjamin Heydecker and Andreas Hegyi},
  title = {Analysis of Traffic Performance of a Merging Assistant Strategy Using Cooperative Vehicles},
  journal = {IEEE Transactions on Intelligent Transportation Systems},
  year = {2015},
  volume = {16},
  number = {4},
  pages = {2094-2103},
  DOI = {10.1109/TITS.2015.2394772}}}

@Article{colletetal2015,
  author = {Roger Collet and Matthieu {de Lapparent} and Laurent Hivert},
  title = {Are French Households Car-Use Addicts? A microeconomic perspective},
  journal = {Journal of Behavioral and Experimental Economics},
  year = {2015},
  volume = {54},
  pages = {86-94},
  DOI = {10.1016/j.socec.2014.12.002}}}

@Article{depalmaetal2015,
  author = {Andr\'e {de Palma} and Nathalie Picard and Matthieu {de Lapparent}},
  title = {Risk and Uncertainty in Urban and Transport Economics},
  journal = {Mathematical Population Studies},
  year = {2015},
  volume = {22},
  number = {1},
  pages = {1-3},
  DOI = {10.1080/08898480.2013.836424}}}

@Article{ChenBier13,
  author = {Jingmin Chen and Michel Bierlaire},
  title = {Probabilistic multimodal map-matching with rich smartphone data},
  journal = {Journal of Intelligent Transportation Systems},
  year = {2015},
  volume = {19},
  number = {2},
  pages = {134-148},
  DOI = {10.1080/15472450.2013.764796},
  note = {Accepted on Oct 22, 2012}}}

Revenue management (RM) can be considered an application of operations research in the transportation industry. For these service companies, it is a difficult task to adjust supply and demand. In order to maximize revenue, RM systems display demand behavior by using historical data. Usually, parametric methods are applied to estimate the probability of choosing a product at a given time. However, parameter estimation becomes challenging when we need to deal with constrained data. In this research, we evaluate the performance of a revenue management system when a nonparametric method for choice probability estimation is chosen. The outcomes of this method have been compared to the total expected revenue using synthetic data.

@Article{ShaHosMar14,
  author = {Shadi {Sharif Azadeh} and Morad Hosseinalifam and Gilles Savard},
  title = {The impact of customer behavior models on revenue management systems},
  journal = {Computational Management Science},
  year = {2015},
  volume = {12},
  number = {1},
  pages = {99-109},
  DOI = {10.1007/s10287-014-0204-z}}}

@Article{PiuKumaBierSper15,
  author = {Francesco Piu and Prem Kumar and Michel Bierlaire and Grazia Speranza},
  title = {Introducing a preliminary Consists Selection in the Locomotive Assignment Problem},
  journal = {Transportation Research Part E: Logistics and Transportation Review},
  year = {2015},
  volume = {82},
  pages = {217-237},
  DOI = {10.1016/j.tre.2015.07.003},
  note = {Accepted on Jul 06, 2015}}}

We present an operational estimation procedure for the estimation of route choice multivariate extreme value (MEV) models based on sampling of alternatives. The procedure builds on the state-of-the-art literature, and in particular on recent methodological developments proposed by Flötteröd and Bierlaire (2013) and Guevara and Ben-Akiva (2013b). Case studies on both synthetic data and a real network demonstrate that the new method is valid and practical.

@Article{LaiBier15,
  author = {Xinjun Lai and Michel Bierlaire},
  title = {Specification of the cross-nested logit model with sampling of alternatives for route choice models},
  journal = {Transportation Research Part B: Methodological},
  year = {2015},
  volume = {80},
  pages = {220-234},
  DOI = {10.1016/j.trb.2015.07.005},
  note = {Accepted on Jul 04, 2015}}}

@Article{Bier15,
  author = {Michel Bierlaire},
  title = {Simulation and optimization: a short review},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2015},
  volume = {55},
  pages = {4-13},
  DOI = {10.1016/j.trc.2015.01.004},
  note = {Accepted on Jan 06, 2015}}}

@Article{AndeFaroEfthBier15,
  author = {Paul Anderson and Bilal Farooq and Dimitrios Efthymiou and Michel Bierlaire},
  title = {Association Generation in Synthetic Population for Transportation Applications: Graph-Theoretic Solution },
  journal = {Transportation Research Record},
  year = {2014},
  volume = {2429},
  pages = {38-50},
  DOI = {10.3141/2429-05},
  note = {Accepted on Feb 14, 2014}}}

Revenue management systems rely on customer data, and are thus affected by the absence of registered demand that arises when a product is no longer available. In the present work, we review the uncensoring (or unconstraining) techniques that have been proposed to deal with this issue, and develop a taxonomy based on their respective features. This study will be helpful in identifying the relative merits of these techniques, as well as avenues for future research.

@Article{SharMarSavard14,
  author = {Shadi {Sharif Azadeh} and Patrice Marcotte and Gilles Savard},
  title = { A taxonomy of demand uncensoring methods in revenue management},
  journal = {Journal of Revenue \& Pricing Management},
  year = {2014},
  volume = {13},
  pages = {440-456},
  DOI = {10.1057/rpm.2014.8}}}

@Article{HuNgGlBi_2014,
  author = {Ricardo Hurtubia and {My Hang} Nguyen and Aur\'elie Glerum and Michel Bierlaire},
  title = {Integrating psychometric indicators in latent class choice models},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2014},
  volume = {64},
  pages = {135-146},
  DOI = {10.1016/j.tra.2014.03.010},
  note = {Accepted on Mar 11, 2014}}}

@Article{ScaHey14,
  author = {Riccardo Scarinci and Benjamin Heydecker},
  title = {Control concepts for facilitating motorway on-ramp merging using intelligent vehicles},
  journal = {Transport Reviews},
  year = {2014},
  volume = {34},
  number = {6},
  pages = {775-797},
  DOI = {10.1080/01441647.2014.983210}}}

In this paper, we propose a methodology to use the communication network infrastructure, in particular WiFi traces, to detect the sequence of activity episodes visited by pedestrians. Due to the poor quality of WiFi localization, a probabilistic method is proposed that infers activity-episode locations based on WiFi traces and calculates the likelihood of observing these traces in the pedestrian network, taking into account prior knowledge. The output of the method consists of candidates of activity-episodes sequences associated with the likelihood to be the true one. The methodology is validated on traces generated by a known sequence of activities, while the performance being evaluated on a set of anonymous users. Results show that it is possible to predict the number of episodes and the activity-episodes locations and durations, by merging information about the activity locations on the map, WiFi measurements and prior information about schedules and the attractivity in pedestrian infrastructure. The ambiguity of each activity episode in the sequence is explicitly measured.

@Article{DanaletFarooqBierlaire_2014,
  author = {Antonin Danalet and Bilal Farooq and Michel Bierlaire},
  title = {A Bayesian Approach to Detect Pedestrian Destination-Sequences from WiFi Signatures},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2014},
  volume = {44},
  pages = {146 - 170},
  DOI = {10.1016/j.trc.2014.03.015},
  note = {Accepted on Mar 26, 2014}}}

This research investigates the measurement of perceptions by means of adjectives freely reported by respondents in semi-open questions. It involved the use of semi-open responses of 1'763 Swiss individuals to develop indicators for a latent variable representing the perception of comfort of public transportation. The indicators are then incorporated into a discrete choice model of revealed mode choices. Perceptions are assumed to impact choice significantly and this research aims at capturing their complexity using adjectives and integrating them into the hybrid choice modeling framework. We exploit a quantification of the adjectives performed by external evaluators. Given the subjectivity that is involved, we analyze the sensitivity of the results across evaluators who rated the adjectives. We observe that the aggregate indicators of demand, such as market shares, elasticities and values of time, are rather robust across evaluators. This is not the case for the disaggregate indicators that may vary substantially across evaluators.

@Article{GleAtaBie_2013,
  author = {Aur\'elie Glerum and Bilge Atasoy and Michel Bierlaire},
  title = {Using semi-open questions to integrate perceptions in choice models},
  journal = {Journal of Choice Modelling},
  year = {2014},
  volume = {10},
  pages = {11-33},
  DOI = {10.1016/j.jocm.2013.12.001},
  note = {Accepted on Dec 13, 2013}}}

Detecting that pedestrians are present in front of a vehicle is highly desirable to avoid dangerous traffic situations. A novel vision-based system is presented to automatically detect far-away pedestrians with low-resolution cameras mounted in vehicles given the contributions of fixed cameras present in the scene. Fixed cameras detect pedestrians by solving an inverse problem built upon a multi-class dictionary of atoms approximating the foreground silhouettes. A sparse-sensing strategy is proposed to extract the foreground silhouettes and classify them in real-time. Mobile cameras detect pedestrians given only their appearance in the fixed cameras. A cascade of compact binary strings is presented to model the appearance of pedestrians and match them across cameras. The proposed system addresses the practical requirements of transportation systems: it runs in real-time with low memory loads and bandwidth consumption. We evaluate the performance of our system when extracted features are severely degraded and the sensing devices are of low quality. Experimental results demonstrate the feasibility of our collaborative vision-based system.

@Article{AlahBierVand13,
  author = {Alexandre Alahi and Michel Bierlaire and Pierre Vandergheynst},
  title = {Robust Real-time Pedestrians Detection in Urban Environments with a Network of Low Resolution Cameras},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2014},
  volume = {39},
  pages = {113-128},
  DOI = {10.1016/j.trc.2013.11.019},
  note = {Accepted on Nov 15, 2013}}}

@Article{as_ijst_2014,
  author = {Amanda Stathopoulos and Edoardo Marcucci},
  title = {De Gustibus Disputandum Est: Non-Linearity in Public Transportation Service Quality Evaluation },
  journal = {International Journal of Sustainable Transportation},
  year = {2014},
  volume = {8},
  number = {1},
  pages = {47-68},
  DOI = {10.1080/15568318.2012.758523},
  note = {Accepted on Dec 11, 2012}}}

@Article{EfthFarrBierAnto15,
  author = {Dimitrios Efthymiou and Bilal Farooq and Michel Bierlaire and Constantinos Antoniou},
  title = {Multidimensional Indicator Analysis for Transport Policy Evaluation},
  journal = {Transportation Research Record},
  year = {2014},
  volume = {2430},
  DOI = {10.3141/2430-09},
  note = {Accepted on Feb 14, 2014}}}

A macroscopic loading model applicable to time-dependent and congested pedestrian flows in public walking areas is proposed. Building on the continuum theory of pedestrian flows and the cell transmission model for car traffic, an isotropic framework is developed that can describe the simultaneous and potentially conflicting propagation of multiple pedestrian groups. The model is formulated at the aggregate level and thus computationally cheap, which is advantageous for studying large-scale problems. A detailed analysis of several basic flow patterns including counter- and cross flows, as well as two generic scenarios involving a corner- and a bottleneck flow is carried out. Various behavioral patterns ranging from disciplined queueing to impatient jostling can be realistically reproduced. Following a systematic model calibration, two case studies involving a Swiss railway station and a Dutch bottleneck flow experiment are presented. A comparison with the social force model and pedestrian tracking data shows a good performance of the proposed model with respect to predictions of travel time and density.

@Article{Haens_Bier_Far_Muhl_2014,
  author = {Flurin H\"anseler and Michel Bierlaire and Bilal Farooq and Thomas M\"uhlematter},
  title = {A macroscopic loading model for time-varying pedestrian flows in public walking areas},
  journal = {Transportation Research Part B: Methodological},
  year = {2014},
  volume = {69},
  pages = {60 -- 80},
  DOI = {10.1016/j.trb.2014.08.003},
  note = {Accepted on Aug 08, 2014}}}

Definitions of flow indicators are derived by adapting Edie's definitions through a stream-based approach and a data-driven spatio-temporal discretization framework. The stream-based approach accounts for the multidirectional nature of pedestrian flows. The data-driven discretization framework, based on three-dimensional Voronoi tessellations, accounts for the pedestrian heterogeneity in the case when only samples of points are available, instead of the analytical description of trajectories. The proposed approach enables the pedestrian flow characterization to be applicable to any space-time domain of interest.

@Article{NikoBier14,
  author = {Marija Nikolic and Michel Bierlaire},
  title = {Pedestrian-oriented Flow Characterization},
  journal = {Transportation Research Procedia},
  year = {2014},
  volume = {2},
  pages = {359-366},
  DOI = {10.1016/j.trpro.2014.09.032},
  note = {Accepted on Oct 02, 2014}}}

In this research, two crucial optimization problems of berth allocation and yard assignment in the context of bulk ports are studied. We discuss how these problems are interrelated and can be combined and solved as a single large scale optimization problem. More importantly we highlight the differences in operations between bulk ports and container terminals which high- lights the need to devise specific solutions for bulk ports. The objective is to minimize the total service time of vessels berthing at the port. We propose an exact solution algorithm based on a branch and price framework to solve the integrated problem. In the proposed model, the mas- ter problem is formulated as a set-partitioning problem, and subproblems to identify columns with negative reduced costs are solved using mixed integer programming. To obtain sub-optimal solutions quickly, a metaheuristic approach based on critical-shaking neighborhood search is pre- sented. The proposed algorithms are tested and validated through numerical experiments based on instances inspired from real bulk port data. The results indicate that the algorithms can be successfully used to solve instances containing up to 40 vessels within reasonable computational time.

@Article{RobeUmanBierRopk13,
  author = {Tom\'a\v{s} Robenek and Nitish Umang and Michel Bierlaire and Stefan Ropke},
  title = {A Branch-and-Price Algorithm to Solve the Integrated Berth Allocation and Yard Assignment Problem in Bulk Ports},
  journal = {European Journal of Operational Research},
  year = {2014},
  volume = {235},
  number = {2},
  pages = {399-411},
  DOI = {10.1016/j.ejor.2013.08.015},
  note = {Accepted on Aug 12, 2013}}}

@Article{EfthKaziAntoTyri14,
  author = {Dimitrios Efthymiou and M. Kaziales and Constantinos Antoniou and Y. Tyrinopoulos},
  title = {Measuring the Effects of Economic Crisis on Users' Perceptions of Public Transport Quality},
  journal = {Transportation Research Record},
  year = {2014},
  volume = {2415},
  pages = {1-12},
  DOI = {10.3141/2415-01}}}

@Article{BindMacfGarrBier13,
  author = {Stefan Binder and Gregory Macfarlane and Laurie Garrow and Michel Bierlaire},
  title = {Associations among Household Characteristics, Vehicle Characteristics and Emissions Failures: An Application of Targeted Marketing Data},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2014},
  volume = {59},
  pages = {122-133},
  DOI = {10.1016/j.tra.2013.11.005},
  note = {Accepted on Nov 04, 2013}}}

@Article{AtasSalaBier13,
  author = {Bilge Atasoy and Matteo Salani and Michel Bierlaire},
  title = {An integrated airline scheduling, fleeting and pricing model for a monopolized market},
  journal = {Computer-Aided Civil and Infrastructure Engineering},
  year = {2014},
  volume = {29},
  number = {2},
  pages = {76-90},
  DOI = {10.1111/mice.12032},
  note = {Accepted on Apr 13, 2013}}}

@Article{ViswBier13,
  author = {Prem Kumar and Michel Bierlaire},
  title = {Multi-Objective Airport Gate Assignment Problem in Planning and Operations},
  journal = {Journal of Advanced Transportation},
  year = {2014},
  volume = {48},
  number = {7},
  pages = {902-926},
  DOI = {10.1002/atr.1235},
  note = {Accepted on May 01, 2013}}}

In the context of the arrival of electric vehicles on the car market, new mathematical models are needed to understand and predict the impact on the market shares. This research provides a comprehensive methodology to forecast the demand of a technology which is not widespread yet, such as electric cars. It aims at providing contributions regarding three issues related to the prediction of the demand for electric vehicles: survey design, model estimation and forecasting. We develop a stated preferences (SP) survey with personalized choice situations involving standard gasoline/diesel cars and electric cars. We specify a hybrid choice model accounting for attitudes towards leasing contracts or practical aspects of a car in the decision-making process. A forecasting analysis based on the collected SP data and market data is performed to evaluate the future demand for electric cars.

@Article{GleStaTheBie_2013,
  author = {Aur\'elie Glerum and Lidija Stankovikj and Micha\"el Th\'emans and Michel Bierlaire},
  title = {Forecasting the demand for electric vehicles: accounting for attitudes and perceptions},
  journal = {Transportation Science},
  year = {2014},
  volume = {48},
  number = {4},
  pages = {483-499},
  DOI = {10.1287/trsc.2013.0487},
  note = {Accepted on May 29, 2013}}}

A new approach for the estimation of bid-rent functions for residential location choice is proposed. The method is based on the bid-auction approach and considers that the expected maximum bid of the auction is a latent variable that can be related to observed price indicators through a measurement equation. The method has the advantage of allowing for the estimation of the parameters of the bid function that explain the heterogeneous preferences of households for location while simultaneously adjusting the expected maximum bid to reproduce realistic values. The model is applied and validated for a case study on the city of Brussels. Results show that the proposed model outperforms other methods for bid-rent estimation, both in terms of real estate prices and spatial distribution of agents, especially when detailed data describing the real estate goods and their prices is not available.

@Article{HurtBier13,
  author = {Ricardo Hurtubia and Michel Bierlaire},
  title = {Estimation of bid functions for location choice and price modeling with a latent variable approach},
  journal = {Networks and Spatial Economics},
  year = {2014},
  volume = {14},
  number = {1},
  pages = {47-65},
  DOI = {10.1007/s11067-013-9200-z},
  note = {Accepted on Jul 16, 2013}}}

@Article{as_jocm_2014,
  author = {Stephane Hess and Amanda Stathopoulos},
  title = {A mixed random utility {\textemdash} Random regret model linking the choice of decision rule to latent character traits},
  journal = {Journal of Choice Modelling},
  year = {2014},
  DOI = {10.1016/j.jocm.2013.12.005},
  note = {Accepted on Jan 06, 2014}}}

In the context of integrated transportation and other urban engineering infrastructure systems, there are many examples of markets, where consumers exhibit price-taking behaviour. While this behaviour is ubiquitous, the underlying mechanism can be captured in a single framework. Here, we present a microsimulation framework of a price-taker market that recognizes this generality and develop efficient algorithms for the associated market clearing problem. By abstracting the problem as a specific graph theoretic problem (i.e. maximum weighted bipartite graph), first we are able to exploit algorithms that are developed in graph theory. We then explore their appropriateness in terms of large-scale integrated urban microsimulations. Based on which, we further develop a generic and efficient clearing algorithm that takes advantage of the features specific to urban price-taker markets. This clearing solution is then used to operationalize two price-taker markets, from two different contexts, within a microsimulation of urban systems. The initial validation of results against the observed data generally shows a close match.

@Article{BF_Market_JTLU2012,
  author = {Bilal Farooq and Eric Miller and Franco Chingcuanco and Martin Giroux-Cook},
  title = {Microsimulation Framework for Urban Price-Taker Markets},
  journal = {Journal of Transport and Land Use},
  year = {2013},
  volume = {6},
  number = {1},
  DOI = {10.5198/jtlu.v6i1.325},
  note = {Accepted on Feb 01, 2012}}}

@Article{FaroBierHurtFloe13,
  author = {Bilal Farooq and Michel Bierlaire and Ricardo Hurtubia and Gunnar Fl\"otter\"od},
  title = {Simulation based population synthesis},
  journal = {Transportation Research Part B: Methodological},
  year = {2013},
  volume = {58},
  pages = {243-263},
  DOI = {10.1016/j.trb.2013.09.012},
  note = {Accepted on Sep 21, 2013}}}

Transportation patterns in big cities are redefined by the growing trend of car ownership and usage costs (e.g. the initial cost of buying a car, the constantly growing fuel prices, additional maintenance and insurance costs and the increased parking demand and time of travel). Under these circumstances, the demand for alternative vehicle-sharing transportation modes, such as carsharing or bikesharing, increases. Companies and authorities planning to develop such schemes need to know the factors driving their adoption, so that they can optimally position these services in a cost-effective way that will maximize their use. In this paper, the results of an on-line survey that was conducted in Greece, a country where carsharing is effectively non-existent and bikesharing is just emerging, are presented and analyzed. Given the nature of the survey and the fact that younger people are the most likely target audience for these services, the analysis focuses on data from the age group 18–35 years old. A factor analysis of the advantages and disadvantages of car and bike-ownership is performed, so as to reveal any latent correlation between the different variables, while the factors affecting the adoption of carsharing and bikesharing schemes are analyzed descriptively. Ordered logit models capturing the willingness of the respondents to progressively join these schemes are also estimated. The model results suggest that respondents with annual income between 15 K and 25 K Euros are more likely to join carsharing or bikesharing systems when they become available in Greece. Carsharing is also expected to mainly attract people that use bus, trolley or tram for their commute, while bikesharing is more likely to attract those who go on foot. Age is also a significant determinant of joining bikesharing, with respondents in the 26–35 years age group being more reluctant than younger ones. Finally, the more environmentally conscious the respondent declares that (s)he is, the more possible it is that (s)he will join one of the two schemes.

@Article{EfthymiouTPolicy2013,
  author = {Dimitrios Efthymiou and Constantinos Antoniou and Paul Waddell},
  title = {Factors affecting the adoption of vehicle sharing systems by young drivers},
  journal = {Transport  Policy},
  year = {2013},
  volume = {29},
  pages = {64{\textendash}73},
  DOI = {10.1016/j.tranpol.2013.04.009}}}

@Article{BergBierCataMiglAmor13,
  author = {Angela Bergantino and Michel Bierlaire and Mario Catalano and Marco Migliore and Salvatore Amoroso},
  title = {Taste heterogeneity and latent preferences in the choice behaviour of freight transport operators},
  journal = {Transport  Policy},
  year = {2013},
  volume = {30},
  pages = {77-91},
  DOI = {10.1016/j.tranpol.2013.08.002}}}

@Article{VaccSalaBier12,
  author = {Ilaria Vacca and Matteo Salani and Michel Bierlaire},
  title = {An exact algorithm for the integrated planning of berth allocation and quay crane assignment},
  journal = {Transportation Science},
  year = {2013},
  volume = {47},
  number = {2},
  pages = {148-161},
  DOI = {10.1287/trsc.1120.0428},
  note = {Accepted on Mar 17, 2012}}}

@Article{as_jocm_2013,
  author = {Stephane Hess and Amanda Stathopoulos},
  title = {Linking response quality to survey engagement: A combined random scale and latent variable approach},
  journal = {Journal of Choice Modelling},
  year = {2013},
  volume = {7},
  pages = {1-12},
  DOI = {10.1016/j.jocm.2013.03.005}}}

@Article{DEfthymEJTL2013,
  author = {Dimitrios Efthymiou and Constantinos Antoniou},
  title = {Measuring the Effects of Transportation Infrastructure Location on Real Estate Prices and Rents. Investigating the Potential Current Impact of a Planned Metro Line},
  journal = {EURO Journal on Transportation and Logistics},
  year = {2013},
  pages = {1-26},
  DOI = {10.1007/s13676-013-0030-4}}}

@Article{ShaLabSav13,
  author = {Shadi {Sharif Azadeh} and Richard Labib and Gilles Savard},
  title = {Railway demand forecasting in revenue management using neural networks},
  journal = {International Journal of Revenue Management},
  year = {2013},
  volume = {7},
  number = {1},
  pages = {18-36},
  DOI = {10.1504/IJRM.2013.053358}}}

The spatial and temporal distribution of built space supply plays an important role in shaping urban form and thus the general travel pattern in an urban area. Within an integrated framework, we are interested in modeling the decisions of a builder in terms of when, where, what type, and how much built-space to build. We present a multidimensional discrete-continuous model formulation for the built space supply decisions that are based on expected profit maximization. The framework is applied to estimate a model for supply of new office space in the Greater Toronto Area (GTA) for the duration of 1986 to 2006. To our knowledge, this work is the first that models the where, when, how much, and what type of office space to supply in a single econometric framework at a fairly disaggregate spatial zoning system. The results indicate a risk taker behaviour on the builders’ part, while market conditions and supply of resources (labour, construction cost etc.) are also found to be important factors in decision making.

@Article{BF_SupplyDec_JTLU2012,
  author = {Bilal Farooq and Eric Miller and Murtaza Haider},
  title = {A Multidimensional Decisions Modelling Framework for Built Space Supply},
  journal = {Journal of Transport and Land Use},
  year = {2013},
  volume = {6},
  number = {3},
  DOI = {10.5198/jtlu.v6i3.350},
  note = {Accepted on May 03, 2012}}}

@Article{BierOsor13,
  author = {Michel Bierlaire and Carolina Osorio},
  title = {Selected papers from the seventh Triennial Symposium on Transportation Analysis (TRISTAN VII)},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2013},
  volume = {27},
  pages = {59}}}

The purpose of this research was to explore how the values of travel time (VTT) and preferences for different modes vary within individuals compared with the variation between observed trips. With 6-week revealed preference panel data and stated preference data from a mode choice context, both collected in Switzerland, a revealed-stated preference logit mode choice model was estimated. The model was applied to simulate how VTT and change in consumer surplus vary across trips within and between individuals over the 6 weeks in response to a hypothetical congestion-charging scheme. The variation in VTT arising from income differences was found to be substantially smaller than the variation in VTT between trips. Moreover, the variability in VTT averaged over all trips within each individual was considerably smaller than the variability in VTT for all observed trips. Therefore, the assumption that variation in VTT between observed trips reflects the variation in the average VTT between individuals, which is usually made in equity analyses, will overstate the between-individual variation. The results suggest that if intraindividual variation in preferences is not taken into account, the negative equity effects of congestion charges are likely to be overestimated.

@Article{BorjCherBier13,
  author = {Maria B\"orjesson and Elisabetta Cherchi and Michel Bierlaire},
  title = {Within Individual Variation in Preferences: Equity Effects of Congestion Charges},
  journal = {Transportation Research Record},
  year = {2013},
  volume = {2382},
  pages = {92-101},
  DOI = {10.3141/2382-11},
  note = {Accepted on Feb 25, 2013}}}

@Article{OsorBier13,
  author = {Carolina Osorio and Michel Bierlaire},
  title = {A simulation-based optimization framework for urban transportation problems},
  journal = {Operations Research},
  year = {2013},
  volume = {61},
  number = {6},
  pages = {1333-1345},
  DOI = {10.1287/opre.2013.1226},
  note = {Accepted on Jun 29, 2013}}}

@Article{FosgMcFaBier13,
  author = {Mogens Fosgerau and Dan McFadden and Michel Bierlaire},
  title = {Choice Probability Generating Functions},
  journal = {Journal of Choice Modelling},
  year = {2013},
  volume = {8},
  pages = {1-18},
  DOI = {10.1016/j.jocm.2013.05.002},
  note = {Accepted on May 15, 2013}}}

@Article{RobiGuidDufoMigo13,
  author = {Thomas Robin and Lionel Guidi and Aur\'elie Dufour and Christophe Migon},
  title = {Statistical distributions of trace metal concentrations in the northwestern Mediterranean atmospheric aerosol},
  journal = {Environmental Monitoring and Assessment},
  year = {2013},
  volume = {185},
  number = {11},
  pages = {9177-9189},
  DOI = {10.1007/s10661-013-3245-9},
  note = {Accepted on Apr 26, 2013}}}

@Article{EfthymiouTRPartA2013,
  author = {Dimitrios Efthymiou and Constantinos Antoniou},
  title = {How do Transport Infrastructure and Policies Affect House Prices and Rents? Evidence from Athens, Greece},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2013},
  volume = {52},
  pages = {1-22},
  DOI = {10.1016/j.tra.2013.04.002},
  note = {Accepted on Apr 22, 2013}}}

In this paper, we study the dynamic hybrid berth allocation problem in bulk ports with the objective to minimize the total service times of the vessels. We propose two exact methods based on mixed integer progra mming and generalized set partitionin g, and a heuristic method based on squeaky wheel optimization, explicitly considering the cargo type on the vessel. The formulations are compared through extensive numer ical experiments based on instances inspired from real bulk port data. The results indicate that the set partitioning method and the heuristic method can be used to obtain near-optimal solutions for even larger problem size.

@Article{UmanBierVac13,
  author = {Nitish Umang and Michel Bierlaire and Ilaria Vacca},
  title = {Exact and Heuristic Methods to Solve the Berth Allocation Problem in Bulk Ports},
  journal = {Transportation Research Part E: Logistics and Transportation Review},
  year = {2013},
  volume = {54},
  pages = {14-31},
  DOI = {10.1016/j.tre.2013.03.003},
  note = {Accepted on Mar 16, 2013}}}

We integrate latent attitudes of individuals into a mode choice model through latent variable and latent class models with the help of psychometric indicators that enable us to measure these attitudes. The aim of the inclusion of attitudes is to better understand the underlying choice preferences of travelers and therefore increase the forecasting power of the choice model. We first present an integrated choice and latent variable model where we include attitudes towards public transportation and environmental issues explaining the utility of public transport. Secondly we present an integrated choice and latent class model where we identify two segments of individuals having different sensitivities to the attributes of the alternatives resulting from their individual characteristics. Calibration of these types of advanced models on our sample has demonstrated the importance of attitudinal variables in the characterization of the population heterogeneity.

@Article{AtaGlerBier2012_DISP,
  author = {Bilge Atasoy and Aur\'elie Glerum and Michel Bierlaire},
  title = {Attitudes towards mode choice in Switzerland},
  journal = {disP - The Planning Review},
  year = {2013},
  volume = {49},
  number = {2},
  pages = {101-117},
  DOI = {10.1080/02513625.2013.827518},
  note = {Accepted on Apr 25, 2012}}}

@Article{KazKoutsTRR_2013,
  author = {Evanthia Kazagli and Haris Koutsopoulos},
  title = {Estimation of Arterial Travel Time from Automatic Number Plate Recognition Data},
  journal = {Transportation Research Record},
  year = {2013},
  volume = {2391},
  pages = {22-31},
  DOI = {10.3141/2391-03},
  note = {Accepted on Feb 26, 2013}}}

@Article{CruzBierThir13,
  author = {Javier Cruz and Michel Bierlaire and Jean-Philippe Thiran},
  title = {Sample and Pixel Weighting Strategies for Robust Incremental Visual Tracking},
  journal = {IEEE Transactions on  Circuits and Systems for Video Technology},
  year = {2013},
  volume = {23},
  number = {5},
  pages = {898-911},
  DOI = {10.1109/TCSVT.2013.2249374 },
  note = {Accepted on Dec 25, 2012}}}

The paper provides analytical evidence of the added-value of flexibility for air transportation systems. More specifically, the impact of a new innovative modular aircraft on the operations of an airline is deeply analyzed. The impact analysis is carried out with an integrated schedule planning model which presents a combination of appropriate optimization and behavioral modeling methodologies. The results show that the flexible system uses the transportation capacity more efficiently by carrying more passengers with less overall capacity. Moreover, it is observed that the flexible system deals better with insufficient transportation capacity. Furthermore, the scheduling decisions are robust to the estimated cost figures of the new system. For the analyzed range of costs, it is always carrying more passengers with less allocated capacity compared to a standard system.

@Article{AtaSalBierLeo_2013,
  author = {Bilge Atasoy and Matteo Salani and Michel Bierlaire and Claudio Leonardi},
  title = {Impact analysis of a flexible air transportation system},
  journal = {European Journal of Transport and Infrastructure Research},
  year = {2013},
  volume = {13},
  number = {2},
  pages = {123-146},
  DOI = {10.18757/ejtir.2013.13.2.2993},
  note = {Accepted on Dec 17, 2012}}}

@Article{DemaDeWe13,
  author = {Marc Demange and Dominique {de Werra}},
  title = {On some coloring problems in grids},
  journal = {Theoretical Computer Science},
  year = {2013},
  volume = {472},
  number = {11},
  pages = {9-27},
  DOI = {10.1016/j.tcs.2012.10.046},
  note = {Accepted on Oct 11, 2012}}}

@Article{as_t_2012,
  author = {Stephane Hess and Amanda Stathopoulos and Danny Campbell and Vikki O'Neill and Sebastian Caussade},
  title = {It{\textquoteright}s not that I don{\textquoteright}t care, I just don{\textquoteright}t care very much: confounding between attribute non-attendance and taste heterogeneity},
  journal = {Transportation},
  year = {2013},
  volume = {40},
  number = {3},
  pages = {583-607},
  DOI = {10.1007/s11116-012-9438-1},
  note = {Accepted on Oct 08, 2012}}}

@Article{ChorBier13,
  author = {Caspar Chorus and Michel Bierlaire},
  title = {An empirical comparison of travel choice models that capture preferences for compromise alternatives},
  journal = {Transportation},
  year = {2013},
  volume = {40},
  number = {3},
  pages = {549-562},
  DOI = {10.1007/s11116-012-9444-3},
  note = {Accepted on Oct 04, 2012}}}

@Article{DEfthymTRR2013,
  author = {Sophia Samoili and Dimitrios Efthymiou and Constantinos Antoniou and Andr\'e-Gilles Dumont},
  title = {Investigation of Lane Flow Distribution on Hard Shoulder Running Freeways},
  journal = {Transportation Research Record},
  year = {2013},
  volume = {2396},
  pages = {133-142},
  DOI = {10.3141/2396-15},
  note = {Accepted on Oct 02, 2012}}}

@Article{BierChenNewm12,
  author = {Michel Bierlaire and Jingmin Chen and Jeffrey Newman},
  title = {A Probabilistic Map Matching Method for Smartphone GPS data},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2013},
  volume = {26},
  pages = {78{\textendash}98},
  DOI = {10.1016/j.trc.2012.08.001},
  note = {Accepted on Aug 03, 2012}}}

@Article{FloeBier13,
  author = {Gunnar Fl\"otter\"od and Michel Bierlaire},
  title = {Metropolis-Hastings sampling of paths},
  journal = {Transportation Research Part B: Methodological},
  year = {2013},
  volume = {48},
  pages = {53-66},
  DOI = {10.1016/j.trb.2012.11.002},
  note = {Accepted on Oct 17, 2012}}}

@Article{BentCostPicoRiesDewe12,
  author = {C\'edric Bentz and Marie-Christine Costa and Christophe Picouleau and Bernard Ries and Dominique {de Werra}},
  title = {d-Transversals of stable sets and vertex covers in weighted bipartite graphs},
  journal = {Journal of Discrete Algorithms},
  year = {2012},
  volume = {17},
  pages = {95-102}}}

@Article{ijte_2012,
  author = {Edoardo Marcucci and Amanda Stathopoulos},
  title = { Multi-level governance and transport policy: the case of local roads in Italy},
  journal = {International journal of transport economics},
  year = {2012},
  volume = {39},
  number = {1},
  pages = {15-38}}}

We consider the production/inventory problem of a manufacturer (or a retailer) under non-stationary and stochastic supply availability. Although supply availability is uncertain, the supplier would be able to predict her near future shortages – and hence supply disruption to (some of) her customers – based on factors such as her pipeline stock information, production schedule, seasonality, contractual obligations, and non-contractual preferences regarding other manufacturers. We consider the case where the information on the availability of supply for the near future, which we refer to as advance supply information (ASI), is provided by the supplier. The customer demand is deterministic but non-stationary over time, and the system costs consist of fixed ordering, holding and backorder costs. We consider an all-or-nothing type of supply availability structure and we show the optimality of a state-dependent (s,S) policy. For the case with no fixed ordering cost we prove various properties of the optimal order-up-to levels and provide a simple characterization of optimal order-up-to levels. For the model with fixed ordering cost, we propose a heuristic algorithm for finding a good ordering strategy. Finally, we numerically elaborate on the value of ASI and provide managerial insights.

@Article{Atasoy_MSc,
  author = {Bilge Atasoy and Refik Gullu and Tarkan Tan},
  title = {Optimal inventory policies with non-stationary supply disruptions and advance supply information},
  journal = {Decision Support Systems},
  year = {2012},
  volume = {53},
  number = {2},
  pages = {269-281},
  DOI = {10.1016/j.dss.2012.01.005}}}

@Article{RiesDeweZenk12,
  author = {Bernard Ries and Dominique {de Werra} and Rico Zenklusen},
  title = {A note on chromatic properties of threshold graphs},
  journal = {Discrete Mathematics},
  year = {2012},
  volume = {312},
  pages = {1838-1843}}}

@Article{LeveDewe12,
  author = {Benjamin L\'ev\^eque and Dominique {de Werra}},
  title = {Graph Transformations preserving the stability number},
  journal = {Discrete Applied Mathematics},
  year = {2012},
  volume = {160},
  pages = {2752-2759}}}

@Article{Pour12,
  author = {Lionel Pournin},
  title = {A result on flip-graph connectivity},
  journal = {Advances in geometry},
  year = {2012},
  volume = {12},
  number = {1},
  pages = {63-82},
  DOI = {10.1515/advgeom.2011.043}}}

We introduce a hybrid discrete choice framework to model the decisions of investors in stock markets. More specifically, we model the decision to buy or sell stocks using a binary logit model with latent classes, characterizing the perception of risk. The model considers the dynamic nature of the underlying decision process and is estimated from the data of a Swiss bank containing 25989 transactional observations from January 2005 to September 2010 for 6 different portfolios. The predictive performance of the model is tested: a cross-validation analysis is performed and the forecasting accuracy of the model is studied in details. Parameters of the model are interpretable and quantify interesting behavioral mechanisms related to investors’ decisions. The predictive capabilities of the model in a real context makes it practicable.

@Article{RobiBier12,
  author = {Thomas Robin and Michel Bierlaire},
  title = {Modeling the behavior of investors},
  journal = {Journal of Choice Modelling},
  year = {2012},
  volume = {5},
  number = {2},
  DOI = {10.1016/S1755-5345(13)70054-X},
  note = {Accepted on Jun 22, 2012}}}

@Article{as_tra_2012,
  author = {Amanda Stathopoulos and Stephane Hess},
  title = {Revisiting reference point formation, gains-losses asymmetry and non-linear sensitivities with an emphasis on attribute specific treatment},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2012},
  volume = {46},
  number = {10},
  pages = {1673-1689},
  DOI = {10.1016/j.tra.2012.08.005},
  note = {Accepted on Aug 14, 2012}}}

@Article{LeeKhelGarroBierPost12,
  author = {Misuk Lee and Alexandre Khelifa and Laurie Garrow and Michel Bierlaire and David Post},
  title = {An analysis of destination choice for opaque airline products using  multidimensional binary logit models },
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2012},
  volume = {46},
  pages = {1641-1653},
  DOI = {10.1016/j.tra.2012.08.009},
  note = {Accepted on Aug 14, 2012}}}

Investigating the factors and processes that influence the spatiotemporal distribution of built space and population in an urban area, plays an extremely important role in our greater understanding of the urban travel behaviour. Existing location of activity centres, especially home and work, strongly influences the short-term individual-level decisions such as mode of transportation, and long-term household-level decisions such as change in job and residential location. Conditions in the built space market also affect households’ and firms’ location and relocation decisions, and hence influence the general travel patterns in an urban area. In this context, this paper addresses a very important, but at the same time, not very widely investigated dimension that plays a key role in the evolution of built space and population distribution: Market. A disequilibrium based microsimulation modelling framework is developed for the built space markets. This framework is then used to operationalize the Greater Toronto and Hamilton Area’s owner-occupied housing market within Integrated Land Use Transportation and Environment (ILUTE) modelling system. Simulation results captured heterogeneity in the transaction prices, due to type of dwellings and different market conditions, in a very disaggregate fashion. The proposed methodology is validated by running the simulation from 1986 to 2006 and comparing the results with the historic data.

@Article{BF_TRA_2012,
  author = {Bilal Farooq and Eric Miller},
  title = {Towards Integrated Land Use and Transportation: A Dynamic Disequilibrium based Microsimulation Framework for Built Space Markets},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2012},
  volume = {46},
  number = {7},
  pages = {1030-1053},
  DOI = {10.1016/j.tra.2012.04.005},
  note = {Accepted on Apr 18, 2012}}}

@Article{DEfthymTRR2012,
  author = {Dimitrios Efthymiou and Constantinos Antoniou and Ioannis Tyrinopoulos},
  title = {Spatially-aware optimal site selection. Method and Application in Mobility Center in Greece},
  journal = {Transportation Research Record},
  year = {2012},
  volume = {2276},
  pages = {146-155},
  DOI = {10.3141/2276-18},
  note = {Accepted on Feb 13, 2012}}}

@Article{CorFloVitTam11,
  author = {Ruben Corthout and Gunnar Fl\"otter\"od and Francesco Viti and Chris Tampere},
  title = {Non-unique flows in macroscopic first-order intersection models},
  journal = {Transportation Research Part B: Methodological},
  year = {2012},
  volume = {46},
  number = {3},
  pages = {343-359},
  DOI = {10.1016/j.trb.2011.10.011},
  note = {Accepted on Oct 28, 2011}}}

A SIFT algorithm in spherical coordinates for omnidirectional images is proposed. This algorithm can generate two types of local descriptors, Local Spherical Descriptors and Local Planar Descriptors. With the first ones, point matching between two omnidirectional images can be performed, and with the second ones, the same matching process can be done but between omnidirectional and planar images. Furthermore, a planar to spherical mapping is introduced and an algorithm for its estimation is given. This mapping allows to extract objects from an omnidirectional image given their SIFT descriptors in a planar image. Several experiments, confirming the promising and accurate performance of the system, are conducted.

@Article{CruzBogdPaquBierThir09,
  author = {Javier Cruz and Iva Bogdanova and Beno{\^\i}t Paquier and Michel Bierlaire and Jean-Philippe Thiran},
  title = {Scale Invariant Feature Transform on the Sphere: Theory and Applications},
  journal = {International Journal of Computer Vision},
  year = {2012},
  volume = {98},
  number = {2},
  pages = {217-241},
  DOI = {10.1007/s11263-011-0505-4},
  note = {Accepted on Oct 21, 2011}}}

@Article{AbouWittBierKaufBenA11,
  author = {Maya Abou-Zeid and Regina Witter and Michel Bierlaire and Vincent Kaufmann and Moshe Ben-Akiva},
  title = {Happiness and Travel Mode Switching: Findings from a Swiss Public Transportation Experiment},
  journal = {Transport  Policy},
  year = {2012},
  volume = {19},
  number = {1},
  pages = {93-104},
  DOI = {10.1016/j.tranpol.2011.09.009},
  note = {Accepted on Sep 09, 2011}}}

This article reports on the calibration and analysis of a fully disaggregate (agent-based) transport simulation for the metropolitan area of Zurich. The agent-based simulation goes beyond traditional transport models in that it equilibrates not only route choice but all-day travel behavior, including departure time choice and mode choice. Previous work has shown that the application of a novel calibration technique that adjusts all choice dimensions at once from traffic counts yields cross-validation results that are competitive with any state-of-the-art four-step model. While the previous study aims at a methodological illustration of the calibration method, this work focuses on the real-world scenario, and it elaborates on the usefulness of the obtained results for further demand analysis purposes.

@Article{FloeNETS2011,
  author = {Gunnar Fl\"otter\"od and Yu Chen and Kai Nagel},
  title = {Behavioral calibration and analysis of a large-scale travel microsimulation},
  journal = {Networks and Spatial Economics},
  year = {2012},
  volume = {12},
  number = {4},
  pages = {481-502},
  DOI = {10.1007/s11067-011-9164-9},
  note = {Accepted on Jul 12, 2011}}}

This paper presents an analytical model, based on finite capacity queueing network theory, to evaluate congestion in protein synthesis networks. These networks are modeled as a set of single server bufferless queues in a tandem topology. This model proposes a detailed state space formulation, which provides a fine description of congestion and contributes to a better understanding of how the protein synthesis rate is deteriorated. The model approximates the marginal stationary distributions of each queue. It consists of a system of linear and quadratic equations that can be decoupled. The numerical performance of this method is evaluated for networks with up to 100,000 queues, considering scenarios with various levels of congestion. It is a computationally efficient and scalable method that is suitable to evaluate congestion for large-scale networks. Additionally, this paper generalizes the concept of blocking: blocking events can be triggered by an arbitrary set of queues. This generalization allows for a variety of blocking phenomena to be modeled. (C) 2011 Elsevier B.V. All rights reserved.

@Article{OsorBier11,
  author = {Carolina Osorio and Michel Bierlaire},
  title = {A tractable analytical model for large-scale congested protein synthesis networks},
  journal = {European Journal of Operational Research},
  year = {2012},
  volume = {219},
  number = {3},
  pages = {588-597},
  DOI = {10.1016/j.ejor.2011.10.037},
  note = {Accepted on Jun 22, 2011}}}

@Article{OsoFloeBier2011,
  author = {Carolina Osorio and Gunnar Fl\"otter\"od and Michel Bierlaire},
  title = {Dynamic network loading: a differentiable model that derives link state distributions},
  journal = {Transportation Research Part B: Methodological},
  year = {2011},
  volume = {45},
  number = {9},
  pages = {1410-1423},
  DOI = {10.1016/j.trb.2011.05.014},
  note = {Accepted on Mar 07, 2011}}}

@Article{MiraBettZahaKreiBarl11,
  author = {Luis Miranda-Moreno and Laetitia Bettex and {Seyed Amir} Zahabi and Tyler Kreider and Philippe Barla},
  title = {Simultaneous Modeling of Endogenous Influence of Urban Form and Public Transit Accessibility on Distance Traveled},
  journal = {Transportation Research Record},
  year = {2011},
  volume = {2255},
  pages = {100-109},
  DOI = {10.3141/2255-11},
  note = {Accepted on Mar 01, 2011}}}

The Vehicle Routing Problem with Time Windows consists of computing a minimum cost set of routes for a fleet of vehicles of limited capacity visiting a given set of customers with known demand, with the additional constraint that each customer must be visited in a specified time window. We consider the case in which time window constraints are relaxed into "soft" constraints, that is penalty terms are added to the solution cost whenever a vehicle serves a customer outside of his time window. We present a branch-and-price algorithm which is the first exact optimization algorithm for this problem

@Article{LibeRighSala10,
  author = {Federico Liberatore and G. Righini and Matteo Salani},
  title = {A column generation algorithm for the vehicle routing problem with soft time windows},
  journal = {4OR - A Quarterly Journal of Operations Research},
  year = {2011},
  volume = {9},
  number = {1},
  pages = {49-82},
  DOI = {10.1007/s10288-010-0136-6},
  note = {Accepted on Jun 18, 2010}}}

We present an operational framework for the calibration of demand models for dynamic traffic simulations, where calibration refers to the estimation of a structurally predefined model's parameters from real data. Our focus is on disaggregate simulators that represent every traveler individually. We calibrate, also at an individual level, arbitrary choice dimensions within a Bayesian framework, where the analyst's prior knowledge is represented by the dynamic traffic simulator itself and the measurements are comprised of time-dependent traffic counts. The approach is equally applicable to an equilibrium-based planning model and to a telematics model of spontaneous and imperfectly informed drivers. It is based on consistent mathematical arguments, yet it is applicable in a purely simulation-based environment and, as our experimental results show, is capable of handling large scenarios.

@Article{FloeBierNageTS10,
  author = {Gunnar Fl\"otter\"od and Michel Bierlaire and Kai Nagel},
  title = {Bayesian demand calibration for dynamic traffic simulations},
  journal = {Transportation Science},
  year = {2011},
  volume = {45},
  number = {4},
  pages = {541-561},
  DOI = {10.1287/trsc.1100.0367},
  note = {Accepted on Dec 01, 2010}}}

In this paper, we present a simulation-based investigation of the potential benefit of route-guidance information in the context of risk-sensitive travelers. We set up a simple two-route scenario where travelers are repeatedly faced with risky route-choice decisions. The risk averseness of the travelers is implicitly controlled through a generic utility function. We vary both the travelers' sensitivity toward risk and the equipment fraction with route-guidance devices and show that the benefits of guided travelers increase with their sensitivity toward risk.

@Article{IllFloNage2010,
  author = {Johannes Illenberger and Gunnar Fl\"otter\"od and Kai Nagel},
  title = {A model of risk-sensitive route-choice behaviour and the potential benefit of route guidance},
  journal = {IEEE Transactions on Intelligent Transportation Systems},
  year = {2011},
  volume = {12},
  number = {2},
  pages = {384-389},
  DOI = {10.1109/TITS.2011.2105266},
  note = {Accepted on Dec 25, 2010}}}

This article describes a new approach to the macroscopic first order modeling and simulation of traffic flow in complex urban road intersections. The framework is theoretically sound, operational, and comprises a large body of models presented so far in the literature.

@Article{FloeRohTRB11,
  author = {Gunnar Fl\"otter\"od and Jannis Rohde},
  title = {Operational macroscopic modeling of complex urban intersections},
  journal = {Transportation Research Part B: Methodological},
  year = {2011},
  volume = {45},
  number = {6},
  pages = {903-922},
  DOI = {10.1016/j.trb.2011.04.001},
  note = {Accepted on Feb 04, 2011}}}

A generation of new models has been proposed to handle some complex human behaviors. These models account for the data ambiguity, and there- fore extend the application field of the discrete choice modeling. The facial expression recognition (FER) is highly relevant in this context. We develop a dynamic facial expression recognition (DFER) framework based on dis- crete choice models (DCM). The DFER consists in modeling the choice of a person who has to label a video sequence representing a facial expression. The originality is based on the the analysis of videos with discrete choice models as well as the explicit modeling of causal effects between the facial features and the recognition of the expression. Five models are proposed. The first assumes that only the last frame of the video triggers the choice of the expression. The second model has two components. The first captures the perception of the facial expression within each frame in the sequence, while the second determines which frame triggers the choice. The third model is an extension of the second model and assumes that the choice of the expression results from the average of perceptions within a group of frames. The fourth and fifth models integrate the panel effect inherent to the estimation data and are respectively extensing the first and second mod- els. The models are estimated using videos from the Facial Expressions and Emotions Database (FEED). Labeling data on the videos has been obtained using an internet survey available at http://transp-or2.epfl.ch/videosurvey/. The prediction capability of the models is studied in order to check their validity by cross-validation using the estimation data.

@Article{RobiBierCruz11,
  author = {Thomas Robin and Michel Bierlaire and Javier Cruz},
  title = {Dynamic facial expression recognition with a discrete choice model},
  journal = {Journal of Choice Modelling},
  year = {2011},
  volume = {4},
  number = {2},
  pages = {95-148},
  DOI = {10.1016/S1755-5345(13)70059-9},
  note = {Accepted on Jun 02, 2011}}}

The ILUTE (Integrated Land Use, Transportation, Environment) model system is an agent-based microsimulation model for the Greater Toronto-Hamilton Area (GTHA) in which disaggregate, process-based models of spatial socio-economic processes are used to evolve the GTHA system state from a known base case to a predicted future year end state in one-year time steps. ILUTE has reached a state of operational implementation in which historical validation runs are being undertaken. A 100% GTA population of persons, families, households and dwelling units has been synthesized for the year 1986. Twenty-year historical simulations (1986-2006) have been run, with model outputs being compared to Canadian Census data and Transportation Tomorrow Survey (TTS) data for 1991, 1996, 2001 and 2006. This paper presents recent findings from these historical validation tests, with particular emphasis on the system’s modelling of demographic evolution of the population and of the region’s housing market.

@Article{BF_TRR_2011,
  author = {Eric Miller and Bilal Farooq and Franco Chingcuanco and David Wang},
  title = {Historical Validation of an Integrated Transport {\textendash} Land Use Model System},
  journal = {Transportation Research Record},
  year = {2011},
  volume = {2},
  number = {2255},
  pages = {91-99},
  DOI = {10.3141/2255-10},
  note = {Accepted on Mar 05, 2011}}}

The Discrete Split Delivery Vehicle Routing Problem with Time Windows (DSDVRPTW) consists of designing the optimal set of routes to serve, at least cost, a given set of customers while respecting constraints on vehicles' capacity and customer time windows. Each customer can be visited by more than one vehicle since each customer's demand, discretized in items, can be split in orders, i.e., feasible combinations of items. In this work, we model the DSDVRPTW assuming that all feasible orders are known in advance. Remarkably, service time at customer's location depends on the delivered combination of items, which is a modeling feature rarely found in literature. We present a flow-based mixed integer program for the DSDVRPTW, we reformulate it via Dantzig-Wolfe and we apply column generation. The proposed branch-and-price algorithm largely outperforms a commercial solver, as shown by computational experiments on Solomon-based instances. A comparison in terms of complexity between constant service time vs delivery-dependent service time is presented and potential savings are discussed. (C) 2011 Elsevier B.V. All rights reserved.

@Article{SalaVacc11,
  author = {Matteo Salani and Ilaria Vacca},
  title = {Branch and Price for the Vehicle Routing Problem with Discrete Split Deliveries and Time Windows},
  journal = {European Journal of Operational Research},
  year = {2011},
  volume = {213},
  number = {3},
  pages = {470-477},
  DOI = {10.1016/j.ejor.2011.03.023},
  note = {Accepted on Mar 09, 2011}}}

Optimization problems with noisy data solved using stochastic programming or robust optimization approaches require the explicit characterization of an uncertainty set U that models the nature of the noise. Such approaches depend on the modeling of the uncertainty set and suffer from an erroneous estimation of the noise.

@Article{EggeSalaBier10,
  author = {Niklaus Eggenberg and Matteo Salani and Michel Bierlaire},
  title = {Uncertainty Feature Optimization: an implicit paradigm for problems with noisy data},
  journal = {Networks},
  year = {2011},
  volume = {57},
  number = {3},
  pages = {270-284},
  DOI = {10.1002/net.20428},
  note = {Accepted on Jun 16, 2010}}}

@Article{SalaDuykSwart2010,
  author = {Matteo Salani and Gaetan Duyckaerts and Peter Swartz},
  title = {Ambush avoidance in Vehicle Routing for valuable delivery},
  journal = {Journal of Transportation Security},
  year = {2010},
  volume = {3},
  number = {1},
  pages = {41-55},
  DOI = {10.1007/s12198-010-0037-0},
  note = {Accepted on Jan 12, 2010}}}

Most of the multi-camera systems assume a well structured environment to detect and match objects across cameras. Cameras need to be fixed and calibrated. In this work, a novel system is presented to detect and match any objects in a network of uncalibrated fixed and mobile cameras. Objects are detected with the mobile cameras given only their observations from the fixed cameras. No training stage and data are used. Detected objects are correctly matched across cameras leading to a better understanding of the scene. A cascade of dense region descriptors is proposed to describe any object of interest. Various region descriptors are studied such as color histogram, histogram of oriented gradients, haar- wavelet responses, and covariance matrices of various features. The proposed descriptor outperforms existing approaches such as scale invariant feature transform (SIFT), or the speeded up robust features (SURF). Moreover, a sparse scan of the image plane is proposed to reduce the search space of the detection and matching process, approaching nearly real- time performance. The approach is robust to changes in illuminations, viewpoints, color distributions and image quality. Partial occlusions are also handled.

@Article{AlahVandBierKunt10,
  author = {Alexandre Alahi and Pierre Vandergheynst and Michel Bierlaire and Murat Kunt},
  title = {Cascade of Descriptors to Detect and Track Objects Across Any Network of Cameras},
  journal = {Computer Vision and Image Understanding},
  year = {2010},
  volume = {114},
  number = {6},
  pages = {624-640},
  DOI = {10.1016/j.cviu.2010.01.004},
  note = {Accepted on Jan 17, 2010}}}

Discrete choice models are defined conditional to the analyst's knowledge of the actual choice set. The common practice for many years has been to assume that individual-based choice sets can be deterministically generated on the basis of the choice context and characteristics of the decision maker. This assumption is not valid or not applicable in many situations, and probabilistic choice set formation procedures must be considered. The constrained multinomial logit model (CMNL) has recently been proposed as a convenient way to deal with this issue, as it is also appropriate for models with a large choice set. In this paper, how well the implicit choice set generation of the CMNL approximates the explicit choice set generation is analyzed as described in earlier research. The results based on synthetic data show that the implicit choice set generation model may be a poor approximation of the explicit model.

@Article{BierHurtFlo_TRB10,
  author = {Michel Bierlaire and Ricardo Hurtubia and Gunnar Fl\"otter\"od},
  title = {An analysis of the implicit choice set generation using the Constrained Multinomial Logit model},
  journal = {Transportation Research Record},
  year = {2010},
  volume = {2175},
  pages = {92-97},
  DOI = {10.3141/2175-11},
  note = {Accepted on Feb 24, 2010}}}

In this paper, we consider the recovery of an airline schedule after an unforeseen event called disruption, making the planned schedule infeasible. We present a modeling framework that allows the consideration of operational constraints within a Column Generation (CG) scheme. We introduce the general concept of recovery network, generated for each individual unit of the problem, and show how unit-specific constraints are modeled using resources. We fully illustrate the concept by solving the Aircraft Recovery Problem (ARP) with maintenance planning, we give some insights into applying the model to the Passenger Recovery Problem (PRP) and we present computational results on real data. (C) 2009 Elsevier Ltd. All rights reserved.

@Article{EggeSalaBier09,
  author = {Niklaus Eggenberg and Matteo Salani and Michel Bierlaire},
  title = {Constraint-specific recovery networks for solving airline recovery problems},
  journal = {Computers \& Operations Research},
  year = {2010},
  volume = {37},
  number = {6},
  pages = {1014-1026},
  DOI = {10.1016/j.cor.2009.08.006 },
  note = {Accepted on Aug 31, 2009}}}

@Article{GaoFrejBenA09,
  author = {Song Gao and Emma Frejinger and Moshe Ben-Akiva},
  title = {Adaptive Route Choices in Risky Traffic Networks: A Prospect Theory Approach},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2010},
  volume = {18},
  number = {5},
  pages = {727-740},
  DOI = {10.1016/j.trc.2009.08.001},
  note = {Accepted on Aug 06, 2009}}}

@Article{KumaKuma10,
  author = {Prem Kumar and Pradeep Kumar},
  title = {A DSS to Optimize Facings on the Shelf of a Retail Store},
  journal = {International Journal of Business Insights and Transformation},
  year = {2010},
  volume = {3},
  number = {1}}}

A recent internet based survey of over 35'000 samples has shown that when different human observers are asked to assign labels to static human facial expressions, different individuals categorize differently the same image. This fact results in a lack of an unique ground-truth, an assumption held by the large majority of existing models for classification. This is especially true for highly ambiguous expressions, especially in the lack of a dynamic context. In this paper we propose to address this shortcoming by the use of Discrete Choice Models (DCM) to describe the choice a human observer is faced to when assigning labels to static facial expressions. Different models of increasing complexity are specified to capture the causal effect between features of an image and its associated expression, using several combinations of different measurements. The sets of measurements we used are largely inspired by FACS but also introduce some new ideas, specific to a static framework. These models are calibrated using maximum likelihood techniques and they are compared with each other using a likelihood ratio test, in order to test for significance in the improvement resulting from adding supplemental features. Through a cross-validation procedure we assess the validity of our approach against overfitting and we provide a comparison with an alternative model based on Neural Networks for benchmark purposes.

@Article{SorcAntoCruzRobiBierThir09,
  author = {Matteo Sorci and Gianluca Antonini and Javier Cruz and Thomas Robin and Michel Bierlaire and Jean-Philippe Thiran},
  title = {Modelling human perception of static facial expressions},
  journal = {Image and Vision Computing},
  year = {2010},
  volume = {28},
  number = {5},
  pages = {790-806},
  DOI = {10.1016/j.imavis.2009.10.003},
  note = {Accepted on Oct 07, 2009}}}

@Article{PattKryvMarcBier10,
  author = {Zachary Patterson and Marko Kryvobokov and Fabrice Marchal and Michel Bierlaire},
  title = {Disaggregate Models with Aggregate Data: Two UrbanSim Applications},
  journal = {Journal of Transport and Land Use},
  year = {2010},
  volume = {3},
  number = {2},
  pages = {5-37},
  DOI = {10.5198/jtlu.v3i2.113},
  note = {Accepted on Jan 08, 2010}}}

This paper seeks to explore the relationship between mode and destination choice in an integrated nested choice model. A fundamental argument can be made that in certain circumstances, the ordering of choices should be reversed from the usual sequence of destination choice preceding mode choice. This results in a travel demand model where travelers are more likely to change destinations than to change transportation modes. For small and medium size urban areas, particularly in the United States, with less well developed public transit systems that draw few choice riders, this assumption makes much more sense than the traditional modeling assumptions. The models used in the new travel modeling system developed for Knoxville, Tennessee utilize this reversed ordering, with generally good results, which required no external tinkering in the logsum parameters.

@Article{NewmBern10,
  author = {Jeffrey Newman and {Vincent Jr} Bernardin},
  title = { Hierarchical ordering of nests in a joint mode and destination choice model},
  journal = {Transportation},
  year = {2010},
  volume = {37},
  number = {4},
  pages = {677-688},
  DOI = {10.1007/s11116-010-9277-x},
  note = {Accepted on Apr 01, 2010}}}

In this paper we integrate at the tactical level two decision problems arising in container terminals: the berth allocation problem, which consists of assigning and scheduling incoming ships to berthing positions, and the quay crane assignment problem, which assigns to incoming ships a certain quay crane profile (i.e. number of quay cranes per working shift). We present two formulations: a mixed integer quadratic program and a linearization which reduces to a mixed integer linear program. The objective function aims, on the one hand, to maximize the total value of chosen quay crane profiles and, oil the other hand, to minimize the housekeeping costs generated by transshipment flows between ships. To Solve the problem we developed a heuristic algorithm which combines tabu search methods and mathematical programming techniques. Computational results on instances based on real data are presented and compared to those obtained through a commercial solver. (C) 2009 Elsevier Ltd. All rights reserved.

@Article{GialMoccSalaVacc09,
  author = {Giovanni Giallombardo and Luigi Moccia and Matteo Salani and Ilaria Vacca},
  title = {Modeling and Solving the Tactical Berth Allocation Problem},
  journal = {Transportation Research Part B: Methodological},
  year = {2010},
  volume = {44},
  number = {2},
  pages = {232-245},
  DOI = {10.1016/j.trb.2009.07.003},
  note = {Accepted on Jul 15, 2009}}}

UrbanSim is an integrated transportation land-use model that has been under development since the late 1990s. It has received a significant amount of attention in the integrated modeling community. It is well known for its disaggregated approach. A number of papers describing the application of UrbanSim have appeared in the formal and gray literatures. Some of these papers report on successful applications of UrbanSim with little description of the amount of effort required to develop an operational model. Those that do report on the effort and challenges of using UrbanSim suggest that substantial data and human resources are required. One recent report quantifies the human resource requirements as an interdisciplinary team of four for three years. This reputation makes many potential users think twice before developing an UrbanSim model. We believe the best way to evaluate UrbanSim for a new region is by having a sense of how it can be used, and how much effort is required to do so. Understanding UrbanSim, however, does not require having a fully operational model. This paper is aimed at researchers and institutions that would like to evaluate UrbanSim, but are concerned about the effort required to do so. Based on two applications (Brussels in Belgium and Lausanne in Switzerland), it describes a procedure to develop a prototype UrbanSim model and how to use it to evaluate UrbanSim for application to a new region. Its objective is to motivate, describe, comment and illustrate a procedure for an efficient evaluation of the use of UrbanSim. Its main contributions are threefold. First, it develops a procedure by which a prototype UrbanSim model can be developed for evaluation purposes in a new region. Second, it provides an analysis of the effort required to do so. Finally, in so doing it advances knowledge in the field of transportation and land-use modeling by helping modelers to evaluate the use of UrbanSim for a particular study region, in a rigorous and systematic way.

@Article{PattBier09,
  author = {Zachary Patterson and Michel Bierlaire},
  title = {Development of Prototype UrbanSim Models},
  journal = {Environment and Planning B},
  year = {2010},
  volume = {37},
  number = {2},
  pages = {344-366},
  DOI = {10.1068/b35107},
  note = {Accepted on Jul 08, 2009}}}

We propose a new heuristic for nonlinear global optimization combining a variable neighborhood search framework with a modified trust-region algorithm as local search. The proposed method presents the capability to prematurely interrupt the local search if the iterates are converging to a local minimum that has already been visited or if they are reaching an area where no significant improvement can be expected. The neighborhoods, as well as the neighbors selection procedure, are exploiting the curvature of the objective function. Numerical tests are performed on a set of unconstrained nonlinear problems from the literature. Results illustrate that the new method significantly outperforms existing heuristics from the literature in terms of success rate, CPU time, and number of function evaluations.

@Article{BierThemZuff09,
  author = {Michel Bierlaire and Micha\"el Th\'emans and Nicolas Zufferey},
  title = {A heuristic for nonlinear global optimization},
  journal = {INFORMS Journal of Computing},
  year = {2010},
  volume = {22},
  number = {1},
  pages = {59-70},
  DOI = {10.1287/ijoc.1090.0343},
  note = {Accepted on Feb 23, 2009}}}

The conditional indirect utility of many random utility maximization (RUM) discrete choice models is specified as a sum of an index V depending on observables and an independent random term. In general, the universe of RUM consistent models is much larger, even fixing some specification of V due to theoretical and practical considerations. In this paper, we explore an alternative RUM model where the summation of V and the error term is replaced by multiplication. This is consistent with the notion that choice makers may sometimes evaluate relative differences in V between alternatives rather than absolute differences. We develop some properties of this type of model and show that in several cases the change from an additive to a multiplicative formulation, maintaining a specification of V, may lead to a large improvement in fit, sometimes larger than that gained from introducing random coefficients in V.

@Article{FosgBier08,
  author = {Mogens Fosgerau and Michel Bierlaire},
  title = {Discrete choice models with multiplicative error terms},
  journal = {Transportation Research Part B: Methodological},
  year = {2009},
  volume = {43},
  number = {5},
  pages = {494-505},
  DOI = {10.1016/j.trb.2008.10.004},
  note = {Accepted on Oct 14, 2008}}}

We analyse the relations between several graph transformations that were introduced to be used in procedures determining the stability number of a graph. We show that all these transformations can be decomposed into a sequence of edge deletions and twin deletions. We also show how some of these transformations are related to the notion of even pair introduced to color some classes of perfect graphs. Then, some properties of edge deletion and twin deletion are given and a conjecture is formulated about the class of graphs for which these transformations can be used to determine the stability number.

@Article{LevedeWe09,
  author = {Benjamin L\'ev\^eque and Dominique {de Werra}},
  title = {Graph transformations preserving the stability number},
  journal = {Electronic Notes in Discrete Mathematics},
  year = {2009},
  volume = {35},
  number = {1},
  pages = {3-8},
  DOI = {10.1016/j.endm.2009.11.002   },
  note = {Accepted on Dec 03, 2009}}}

We propose and validate a model for pedestrian walking behavior, based on discrete choice modeling. Two main types of behavior are identified: unconstrained and constrained. By unconstrained, we refer to behavior patterns which are independent from other individuals. The constrained patterns are captured by a leader-follower model and by a collision avoidance model. The spatial correlation between the alternatives is captured by a cross nested logit model. The model is estimated by maximum likelihood estimation on a real data set of pedestrian trajectories, manually tracked from video sequences. The model is successfully validated using a bi-directional flow data set, collected in controlled experimental conditions at Delft university.

@Article{RobiAntoBierCruz08,
  author = {Thomas Robin and Gianluca Antonini and Michel Bierlaire and Javier Cruz},
  title = {Specification, estimation and validation of a pedestrian walking behavior model},
  journal = {Transportation Research Part B: Methodological},
  year = {2009},
  volume = {43},
  number = {1},
  pages = {36-56},
  DOI = {10.1016/j.trb.2008.06.010},
  note = {Accepted on Jun 11, 2008}}}

@Article{MartAguiHurt08,
  author = {Francesco Martinez and Felipe Aguila and Ricardo Hurtubia},
  title = {The Constrained Multinomial Logit Model: A Semi-Compensatory Choice Model},
  journal = {Transportation Research Part B: Methodological},
  year = {2009},
  volume = {43},
  number = {3},
  pages = {365-377},
  DOI = {10.1016/j.trb.2008.06.006},
  note = {Accepted on Jun 17, 2008}}}

We propose a new trust region based optimization algorithm for solving unconstrained nonlinear problems whose second derivatives matrix is singular at a local solution. We give a theoretical characterization of the singularity in this context and we propose an iterative procedure which allows to identify a singularity in the objective function during the course of the optimization algorithm, and artificially adds Curvature to the objective function. Numerical tests are performed on a set of unconstrained nonlinear problems, both singular and non-singular. Results illustrate the significant performance improvement compared to classical trust region and filter algorithms proposed in the literature. The approach is also shown to be competitive with tensor methods in terms of efficiency while reaching a higher level of robustness. (C) 2008 Elsevier B.V. All rights reserved

@Article{BierThem08,
  author = {Michel Bierlaire and Micha\"el Th\'emans},
  title = {Dealing with singularities in nonlinear unconstrained optimization},
  journal = {European Journal of Operational Research},
  year = {2009},
  volume = {196},
  number = {1},
  pages = {33-42},
  DOI = {10.1016/j.ejor.2008.02.036},
  note = {Accepted on Feb 24, 2008}}}

We present an exact optimization algorithm for the Orienteering Problem with Time Windows (OPTW). The algorithm is based on bi-directional and bounded dynamic programming with decremental state space relaxation. We compare different strategies proposed in the literature to guide decremental state space relaxation: our experiments on instances derived from the literature show that there is no dominance between these strategies. We also propose a new heuristic technique to initialize the critical vertex set and we provide experimental evidence of its effectiveness

@Article{RighiSala08,
  author = {G. Righini and Matteo Salani},
  title = {Decremental state space relaxation strategies and initialization heuristics for solving the orienteering problem with time windows with dynamic programming},
  journal = {Computers \& Operations Research},
  year = {2009},
  volume = {36},
  number = {4},
  pages = {1191-1203},
  DOI = {10.1016/j.cor.2008.01.003},
  note = {Accepted on Jan 14, 2008}}}

@Article{BierSala09,
  author = {Michel Bierlaire and Matteo Salani},
  title = {Selected papers from the Triennial symposium on transportation  analysis (TRISTAN), Phuket, Thailand, June 11{\textendash}15, 2007, Special Issue of Transportation Research Part C },
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2009},
  volume = {17},
  number = {2},
  pages = {105},
  DOI = {10.1016/j.trc.2008.12.001 },
  note = {Accepted on Oct 28, 2008}}}

@Article{BentCostPicoRiesdeWe09,
  author = {C\'edric Bentz and Marie-Christine Costa and Christophe Picouleau and Bernard Ries and Dominique {de Werra}},
  title = {Degree-constrained edge partitioning in graphs arising from discrete tomography},
  journal = {Journal of Graph Algorithms and Applications},
  year = {2009},
  volume = {13},
  number = {2},
  pages = {99-118},
  note = {Accepted on Nov 01, 2008}}}

We present an optimization algorithm developed for a provider of software planning tools for distribution logistics companies. The algorithm computes a daily plan for a heterogeneous fleet of vehicles, that can depart from different depots and must visit a set of customers for delivery operations. Besides multiple capacities and time windows associated with depots and customers, the problem also considers incompatibility constraints between goods, depots, vehicles and customers, maximum route length and durations, upper limits on the number of consecutive driving hours and compulsory drivers' rest periods, the possibility to skip some customers and to use express courier services instead of the given fleet to fulfill some orders, the option of splitting up the orders, and the possibility of open routes that do not terminate at the depots. Moreover, the cost of each vehicle route is computed through a system of fares, depending on the locations visited by the vehicle, the distance traveled, the vehicle load and the number of stops along the route. We developed a column generation algorithm, where the pricing problem is a particular resource constrained elementary shortest path problem, solved through a bounded bi-directional dynamic programming algorithm. We describe how to encode the cost function and the complicating constraints by an appropriate use of resources and we present computational results on real instances obtained from the software company.

@Article{CeseRighSala08,
  author = {Alberto Ceselli and G. Righini and Matteo Salani},
  title = {A column generation algorithm for a vehicle routing problem with economies of scale and additional constraints},
  journal = {Transportation Science},
  year = {2009},
  volume = {43},
  number = {1},
  pages = {56-69},
  DOI = {10.1287/trsc.1080.0256},
  note = {Accepted on Nov 18, 2008}}}

We consider the complexity of approximation for the INDEPENDENT DOMINATING SET problem in 2P(3)-free graphs, i.e., graphs that do not contain two disjoint copies of the chordless path on three vertices as all induced subgraph. We show that, if P not equal NP, the problem cannot be approximated for 2P(3)-freegraphs in polynomial time within a factor of n(1-epsilon) for any constant epsilon > 0, where n is the number of vertices ill the graph. Moreover, we show that the result holds even if the 2P(3)-free graph is restricted to being weakly chordal (and thereby perfect). (C) 2008 Elsevier B.V. All rights reserved.

@Article{OrloGorddeWe09,
  author = {Yury Orlovich and Valery Gordon and Dominique {de Werra}},
  title = {On the inapproximability of independent domination in 2P3-free perfect graphs },
  journal = {Theoretical Computer Science},
  year = {2009},
  volume = {410},
  number = {8-10},
  pages = {977-982},
  DOI = {10.1016/j.tcs.2008.11.023 },
  note = {Accepted on Nov 24, 2008}}}

Analytic queueing network models often assume infinite capacity queues due to the difficulty of grasping the between-queue correlation. This correlation can help to explain the propagation of congestion. We present an analytic queueing network model which preserves the finite capacity of the queues and uses structural parameters to grasp the between-queue correlation. Unlike pre-existing models it maintains the network topology and the queue capacities exogenous. Additionally, congestion is directly modeled via a novel formulation of the state space of the queues which explicitly captures the blocking phase. The model can therefore describe the sources and effects of congestion.

@Article{OsorBier08,
  author = {Carolina Osorio and Michel Bierlaire},
  title = {An analytic finite capacity queueing network model capturing the propagation of congestion and blocking},
  journal = {European Journal of Operational Research},
  year = {2009},
  volume = {196},
  number = {3},
  pages = {996-1007},
  DOI = {10.1016/j.ejor.2008.04.035},
  note = {Accepted on Apr 23, 2008}}}

Given an undirected graph G = (V, E) with matching number v(G), we define d-blockers as subsets of edges B such that nu((V, E \ B)) <= nu(G) - d. We define d-transversals T as subsets of edges such that every maximum matching M has |M boolean AND T| >= d. We explore connections between d-blockers and d-transversals. Special classes of graphs are examined which include complete graphs, regular bipartite graphs, chains and cycles and we construct minimum d-transversals and d-blockers in these special graphs. We also study the complexity status of finding minimum transversals and blockers in arbitrary graphs. (C) 2009 Elsevier B.V. All rights reserved.

@Article{ZenkRiesPicoDeWeCostBent09,
  author = {Rico Zenklusen and Bernard Ries and Christophe Picouleau and Dominique {de Werra} and Marie-Christine Costa and C\'edric Bentz},
  title = {Blockers and transversals},
  journal = {Discrete Mathematics},
  year = {2009},
  volume = {309},
  number = {13},
  pages = {4306-4314},
  DOI = {10.1016/j.disc.2009.01.006},
  note = {Accepted on Jan 07, 2009}}}

We study the problem where a robot has to pick up items of different sizes which are stored along a corridor. A natural requirement is that the items have to be collected in decreasing order of their sizes. We deal with various systems according to the location of the Entry/Exit station where the robot unloads the collected items after each trip along the corridor. The links of these systems with generalized coloring problems and other applications such that train shunting and pallet loading problems are discussed and related results are obtained. We conclude with several open questions on the topic. (C) 2007 Elsevier B.V. All rights reserved.

@Article{DemaEkimdeWe09,
  author = {Marc Demange and Tinaz Ekim and Dominique {de Werra}},
  title = {A tutorial on the use of graph coloring for some problems in robotics},
  journal = {European Journal of Operational Research},
  year = {2009},
  volume = {1},
  number = {1},
  pages = {41-55},
  DOI = {10.1016/j.ejor.2007.09.018   },
  note = {Accepted on Sep 09, 2007}}}

Starting from the famous Konigsberg bridge problem which Euler described in 1736, we intend to show that some results obtained 180 years later by Konig are very close to Euler's discoveries.

@Article{deWe09,
  author = {Dominique {de Werra}},
  title = {From L. Euler to D. K\"onig},
  journal = {RAIRO-Operations Research},
  year = {2009},
  volume = {43},
  pages = {247-251},
  DOI = {10.1051/ro/2009020},
  note = {Accepted on Jan 30, 2009}}}

In recent years, many works on geometric image representation have appeared in the literature. Geometric video representation has not received such an important attention so far, and only some initial works in the area have been presented. Works on geometric multi-dimensional signal representations have established a close relation with signal expansions on redundant dictionaries. For this purpose, Matching Pursuits (MP) have shown to be an interesting tool to obtain such expansions. Recently, most important limitations of MP have been underlined, and alternative algorithms like Weighted-MP have been proposed to address these. This work explores the use of Weighted-MP as a new framework for motion-adaptive geometric video approximations. We study a novel algorithm to decompose video sequences in terms of few, salient video components that jointly represent the geometric and motion content of a scene. Experimental coding results on highly geometric content show that the proposed paradigm has the potential to exploit spatio-temporal geometry adaptation, as well as that 2D Weighted-MP improves the representation compared to those based on 2D MP. Furthermore, the extracted video components represent relevant visual structures with high saliency. In an example application, such components are effectively used as video descriptors for the joint audio-video analysis of multimedia sequences. Overall results are interesting, encouraging further research on the application of Weighted-MP for geometric video representations.

@Article{DivoMonaFiguVandBier09,
  author = {Oscar {Divorra Escoda} and Gianluca Monaci and Rosa {Figueras i Ventura} and Pierre Vandergheynst and Michel Bierlaire},
  title = {Geometric Video Approximation Using Weighted Matching Pursuit},
  journal = {IEEE Transactions on Image Processing},
  year = {2009},
  volume = {18},
  number = {8},
  pages = {1703-1716},
  DOI = {10.1109/TIP.2009.2021315},
  note = {Accepted on Feb 28, 2009}}}

Derivative-free optimization involves the methods used to minimize an expensive objective functionwhen its derivatives are not available. We present here a trust-region algorithmbased on Radial Basis Functions (RBFs). The main originality of our approach is the use of RBFs to build the trust-region models and our management of the interpolation points based on Newton fundamental polynomials. Moreover the complexity of ourmethod is very attractive. We have tested the algorithmagainst the best state-of-theart methods (UOBYQA, NEWUOA, DFO). The tests on the problems from the CUTEr collection show that BOOSTERS is performing very well on medium-size problems. Moreover, it is able to solve problems of dimension 200, which is considered very large in derivative-free optimization.

@Article{OeuvBier06-booster,
  author = {Rodrigue Oeuvray and Michel Bierlaire},
  title = {BOOSTERS: a derivative-free algorithm based on radial basis functions},
  journal = {International Journal of Modelling and Simulation},
  year = {2009},
  volume = {29},
  number = {1},
  pages = {26-36},
  DOI = {10.2316/Journal.205.2009.1.205-4634},
  note = {Accepted on Jul 10, 2006}}}

This paper presents a new paradigm for choice set generation in the context of route choice model estimation. We assume that the choice sets contain all paths connecting each origin-destination pair. Although this is behaviorally questionable, we make this assumption in order to avoid bias in the econometric model. These sets are in general impossible to generate explicitly. Therefore, we propose an importance sampling approach to generate subsets of paths suitable for model estimation. Using only a subset of alternatives requires the path utilities to be corrected according to the sampling protocol in order to obtain unbiased parameter estimates. We derive such a sampling correction for the proposed algorithm.

@Article{FrejBierBenA09,
  author = {Emma Frejinger and Michel Bierlaire and Moshe Ben-Akiva},
  title = {Sampling of Alternatives for Route Choice Modeling},
  journal = {Transportation Research Part B: Methodological},
  year = {2009},
  volume = {43},
  number = {10},
  pages = {984-994},
  DOI = {10.1016/j.trb.2009.03.001},
  note = {Accepted on Mar 03, 2009}}}

Extensions and variations of the basic problem of graph coloring are introduced. The problem consists essentially in finding in a graph G a k-coloring, i.e., a partition V-1,...,V-k of the vertex set of G such that, for some specified neighborhood (N) over tilde(upsilon) of each vertex upsilon, the number of vertices in (N) over tilde(upsilon) boolean AND V-i is (at most) a given integer h(upsilon)(i). The complexity of some variations is discussed according to (N) over tilde(upsilon), which may be the usual neighbors, or the vertices at distance at most 2, or the closed neighborhood of upsilon (upsilon and its neighbors). Polynomially solvable cases are exhibited (in particular when G is a special tree). (C) 2009 Elsevier B.V. All rights reserved.

@Article{CostDeWePicoRies09,
  author = {Marie-Christine Costa and Dominique {de Werra} and Christophe Picouleau and Bernard Ries},
  title = {Graph coloring with cardinality constraints on the neighborhoods},
  journal = {Discrete Optimization},
  year = {2009},
  volume = {6},
  pages = {362-369},
  DOI = {10.1016/j.disopt.2009.04.005},
  note = {Accepted on Apr 22, 2009}}}

We study complexity and approximation of MIN WEIGHTED NODE COLORING in planar, bipartite and split graphs. We show that this problem is NP-hard in planar graphs, even if they are triangle-free and their maximum degree is bounded above by 4. Then, we prove that MIN WEIGHTED NODE COLORING is NP-hard in Pg-free bipartite graphs, but polynomial for P-5-free bipartite graphs. We next focus on approximability in general bipartite graphs and improve earlier approximation results by giving approximation ratios matching inapproximability bounds. We next deal with MIN WEIGHTED EDGE COLORING in bipartite graphs. We show that this problem remains strongly NP-hard, even in the case where the input graph is both cubic and planar. Furthermore, we provide an inapproximability bound of 7/6 - epsilon, for any epsilon > 0 and we give an approximation algorithm with the same ratio. Finally, we show that MIN WEIGHTED NODE COLORING in split graphs can be solved by a polynomial time approximation scheme. (C) 2008 Elsevier B.V. All rights reserved.

@Article{deWeDemaEscoMonnPasc09,
  author = {Dominique {de Werra} and Marc Demange and Bruno Escoffier and J\'er\^ome Monnot and Vangelis Paschos},
  title = {Weighted coloring on planar, bipartite and split graphs: Complexity and approximation},
  journal = {Discrete Applied Mathematics},
  year = {2009},
  volume = {157},
  number = {4},
  pages = {819-832},
  DOI = {10.1016/j.dam.2008.06.013},
  note = {Accepted on Jun 06, 2008}}}

The resource constrained elementary shortest path problem (RCESPP) arises as a pricing subproblem in branch-and-price algorithms for vehicle-routing problems with additional constraints. We address the optimization of the RCESPP and we present and compare three methods. The first method is a well-known exact dynamic-programming algorithm improved by new ideas, such as bidirectional search with resource-based bounding. The second method consists in a branch-and-bound algorithm, where lower bounds are computed by dynamic-programming with state-space relaxation; we show how bounded bidirectional search can be adapted to state-space relaxation and we present different branching strategies and their hybridization. The third method, called decremental state-space relaxation, is a new one; exact dynamic-programming and state-space relaxation are two special cases of this new method. The experimental comparison of the three methods is definitely favorable to decrement state-space relaxation. Computational results are given for different kinds of resources, arising from the capacitated vehicle-routing problem, the vehicle-routing problem with distribution and collection, and the vehicle-routing problem with capacities and time windows.

@Article{RighSala07,
  author = {G. Righini and Matteo Salani},
  title = {New dynamic programming algorithms for the resource constrained shortest path problem.},
  journal = {Networks},
  year = {2008},
  volume = {51},
  number = {3},
  pages = {155-170},
  DOI = {10.1002/net.20212},
  note = {Accepted on May 05, 2007}}}

@Article{CornJost08,
  author = {Denis Cornaz and Vincent Jost},
  title = {A one-to-one correspondence between colorings and stable sets},
  journal = {Operations Research Letters},
  year = {2008},
  volume = {36},
  number = {0},
  pages = {673-676},
  DOI = {10.1016/j.orl.2008.08.002},
  note = {Accepted on Aug 07, 2008}}}

Route choice models are difficult to design and to estimate for various reasons. In this paper we focus on issues related to data. Indeed, real data in its original format are not related to the network used by the modeler and do therefore not correspond to path definitions. Typical examples are data collected with the Global Positioning System (GPS) or respondents describing chosen itineraries to interviewers. Data manipulation is then necessary in order to obtain network compliant paths. We argue that such manipulations introduce bias and errors and should be avoided. We propose a general modeling framework that reconcile network-free data with a network based model without data manipulations. The concept that bridges the gap between the data and the model is called Domain of Data Relevance and corresponds to a physical area in the network where a given piece of data is relevant. We illustrate the framework on simple examples for two different types of data (GPS data and reported trips). Moreover, we present estimation results of Path Size Logit and Subnetwork models based on a dataset of reported trips collected in Switzerland. The network is to our knowledge the largest one used in the literature for route choice analysis based on revealed preferences data.

@Article{BierFrej07,
  author = {Michel Bierlaire and Emma Frejinger},
  title = {Route choice modeling with network-free data},
  journal = {Transportation Research Part C: Emerging Technologies},
  year = {2008},
  volume = {16},
  number = {2},
  pages = {187-198},
  DOI = {10.1016/j.trc.2007.07.007},
  note = {Accepted on Jul 23, 2007}}}

In the presence of choice-based sampling strategies for data collection, the property of Multinomial Logit (MNL) models, that consistent estimâtes of all parameters but the constants can be obtained from an Exogenous Sample Maximum Likelihood (ESML) estimation, does not hold in general for Generalized Extreme Value (GEV) models. We propose a consistent ESML estimator for GEV models in this context. We first identify a specific class of GEV models with the desired property that, similarly to MNL, the constants absorb the potential bias. We then propose a new and simpleWeighted Conditional Maximum Likelihood (WCML) estimator for the more general case. Contrarily to the Weighted Exogenous Sample Maximum Likelihood (WESML) estimator by Manski and Lerman (1977), the new WCML estimator does not require an external knowledge of the market shares. We illustrate the use of the estimator on synthetic and real data.

@Article{BierBoldMcFa07,
  author = {Michel Bierlaire and Denis Bolduc and Dan McFadden},
  title = {The estimation of Generalized Extreme Value models from choice-based samples},
  journal = {Transportation Research Part B: Methodological},
  year = {2008},
  volume = {42},
  number = {4},
  pages = {381-394},
  DOI = {10.1016/j.trb.2007.09.003},
  note = {Accepted on Sep 20, 2007}}}

Abstract Generalized extreme value (GEV) models provide a convenient way to model choice behavior that is consistent with utility maximization theory, but the development of specific new models within the GEV family has been slow, due to the difficulty of ensuring new formulations comply with all the GEV rules. The network GEV structure introduced by Daly and Bierlaire [Daly, A. and M. Bierlaire, 2006. A general and operational representation of Generalised Extreme Value models. Transportation Research Part B, v. 40, pp. 285-305.] provides a tool to quickly generate new models in the GEV family, without the burden of complex analysis of the new model to ensure its properties. This paper further develops the network GEV tool, describing several methodologies for correctly normalizing the allocation parameters in such models, to ensure unbiasedness. These methods vary depending on the structure of the underlying network.

@Article{Newman08,
  author = {Jeffrey Newman},
  title = {Normalization of network generalized extreme value models},
  journal = {Transportation Research Part B: Methodological},
  year = {2008},
  volume = {42},
  number = {10},
  pages = {958-969},
  DOI = {10.1016/j.trb.2008.04.001 },
  note = {Accepted on Apr 20, 2008}}}

@Article{OeuvBier06-doped,
  author = {Rodrigue Oeuvray and Michel Bierlaire},
  title = {A doped derivative-free algorithm},
  journal = {International Journal of Modelling and Simulation},
  year = {2008},
  volume = {28},
  number = {4},
  pages = {387-393},
  DOI = {10.2316/Journal.205.2008.4.205-4660},
  note = {Accepted on Jul 01, 2006}}}

@Article{GaoFrejBenA08,
  author = {Song Gao and Emma Frejinger and Moshe Ben-Akiva},
  title = {Adaptive Route Choice Models in Stochastic Time-Dependent Networks},
  journal = {Transportation Research Record},
  year = {2008},
  volume = {2085},
  pages = {136-143},
  DOI = {10.3141/2085-15},
  note = {Accepted on Mar 12, 2008}}}

Mutual information is a widely used similarity measure for aligning multimodal medical images. At its core it relies on the computation of a discrete joint histogram, which itself requires image samples for its estimation. In this paper we study the influence of the sampling process. We show that quasi-random sampling based on Halton sequences outperforms methods based on regular sampling or on random sampling. Our results suggest that sampling itself—and not interpolation, as was previously believed— is the source of two major problems associated with mutual information: the grid effect, whereby grid-aligning transformations are favored, and the overlap problem, whereby the similarity measure exhibits discontinuities. Both defects tend to impede the accuracy of registration; they also result in reduced robustness because of the presence of local optima. By estimating the joint histogram by quasi-random sampling, we solve both issues at the same time.

@Article{ThevBierUnse06,
  author = {Philippe Th\'evenaz and Michel Bierlaire and Micha\"el Unser},
  title = {Halton Sampling for Image Registration Based on Mutual Information},
  journal = {Sampling Theory in Signal and Image Processing},
  year = {2008},
  volume = {7},
  number = {2},
  pages = {141-171},
  note = {Accepted on Mar 28, 2006}}}

This paper presents the findings of a study looking into the valuation of travel time savings (VTTS) in Switzerland, across modes as well as across purpose groups. The study makes several departures from the usual practice in VTTS studies, with the main one being a direct representation of the income and distance elasticity of the VTTS measures. Here, important gains in model performance and significantly different results are obtained through this approach. Additionally, the analysis shows that the estimation of robust coefficients for congested car travel time is hampered by the low share of congested time in the overall travel time, and the use of an additional rate-of-congestion coefficient, in addition to a generic car travel time coefficient, is preferable. Finally, the analysis demonstrates that the population mean of the indicators calculated is quite different from the sample means and presents methods to calculate those, along with the associated variances. These variances are of great interest as they allow the generation of confidence intervals, which can be extremely useful in cost-benefit analyses.

@Article{AxhaHessKoenAbayBateBier07,
  author = {Kay Axhausen and Stephane Hess and Arnd Koenig and Georg Abay and John Bates and Michel Bierlaire},
  title = {Income and distance elasticities of values of travel time savings: new Swiss results},
  journal = {Transport  Policy},
  year = {2008},
  volume = {15},
  number = {3},
  pages = {173-185},
  DOI = {10.1016/j.tranpol.2008.02.001},
  note = {Accepted on Feb 16, 2007}}}

Concentrations of lead (Pb) in the atmospheric aerosol were monitored in 1986–87, 1992–93, 1995, 1997–98 and 2003–2005 at a North-Western Mediterranean coastal sampling station. After the implementation of antipollution policies on automotive Pb in the second half of the 1980s, Pb concentrations were markedly lowered and then the decrease slowed down, at the latest in 2003, resulting in average concentrations varying between 6.6 and 5.8 ngm3 in 2004 and 2005, respectively. This represents a decrease by a factor of 82%, approximately, between 1986–87 and 2005. Reproducible seasonal patterns are observed, with highest Pb loads occurring at the end of winter and at the end of summer/beginning of autumn. The slowing down of aerosol Pb concentration decrease in the troposphere is expected to be rapidly observed in the Western Mediterranean water column.

@Article{MigoRobiDufoGent08,
  author = {Christophe Migon and Thomas Robin and Aur\'elie Dufour and Bernard Gentili},
  title = {Decrease of lead concentrations in the Western Mediterranean atmosphere during the last 20 years},
  journal = {Atmospheric Environment},
  year = {2008},
  volume = {42},
  pages = {815-821},
  DOI = {10.1016/j.atmosenv.2007.10.078},
  note = {Accepted on Oct 31, 2007}}}

The Quebec City-Windsor corridor (the Corridor) is the busiest and most important trade and transportation corridor in Canada. The transportation sector is the second largest greenhouse gas (GHG) emission category in the country. This paper develops estimates of the potential for CO2 emission reductions in the freight transportation sector by estimating demand for premium-intermodal services between the main Corridor destinations. CO2 reductions are estimated on the basis of a stated-preference carrier-choice survey of shippers in the Corridor. Survey data were used to develop mode share models for five different categories of shipments between eighteen city-pairs. A railyard-catchment approach was taken to arrive at estimates of contestable intercity truck traffic using a subset of the Ontario Ministry of Transportation’s Commercial Vehicle Survey. CO2 emissions were based on current truck traffic estimates, and emissions factors obtained from MOBILE6.2C. The results show that premium-intermodal service has the potential to capture a significant share of traffic between the main Corridor destinations with potential CO2 emissions reductions in the range of 0.058 to 0.484 Mt a year.

@Article{PattEwinHaid2008,
  author = {Zachary Patterson and Gordon Ewing and Murtaza Haider},
  title = {The Potential for Premium-intermodal Services to Reduce Freight CO2 Emissions in the Quebec City - Windsor Corridor},
  journal = {Transportation Research Part D: Transport and Environment},
  year = {2008},
  volume = {13},
  number = {1},
  pages = {1-9},
  DOI = {10.1016/j.trd.2007.10.001},
  note = {Accepted on Oct 01, 2007}}}

@Article{BogeBierHoge07,
  author = {Enide Bogers and Michel Bierlaire and Serge Hoogendoorn},
  title = {Modeling Learning in Route Choice},
  journal = {Transportation Research Record},
  year = {2007},
  volume = {2014},
  pages = {1-8},
  DOI = {10.3141/2014-01},
  note = {Accepted on Mar 02, 2007}}}

We propose an extension of secant methods for nonlinear equations using a population of previous iterates. Contrarily to classical secant methods, where exact interpolation is used, we prefer a least squares approach to calibrate the linear model. We propose an explicit control of the numerical stability of the method. We show that our approach can lead to an update formula. In that case, we prove the local convergence of the corresponding undamped quasi-Newton method. Finally, computational comparisons with classical quasi-Newton methods highlight a significant improvement in terms of robustness and number of function evaluations. We also present numerical tests showing the robust behavior of our method in the presence of noise.

@Article{BierCritThem06,
  author = {Michel Bierlaire and Frank Crittin and Micha\"el Th\'emans},
  title = {A multi-iterate method to solve systems of nonlinear equations},
  journal = {European Journal of Operational Research},
  year = {2007},
  volume = {183},
  number = {1},
  pages = {20-41},
  DOI = {10.1016/j.ejor.2006.09.080}}}

The choice of a specific distribution for random parameters of discrete choice models is a critical issue in transportation analysis. Indeed, various pieces of research have demonstrated that an inappropriate choice of the distribution may lead to serious bias in model forecast and in the estimated means of random parameters. In this paper, we propose a practical test, based on seminonparametric techniques. The test is analyzed both on synthetic and real data, and is shown to be simple and powerful.

@Article{FosgBier07,
  author = {Mogens Fosgerau and Michel Bierlaire},
  title = {A practical test for the choice of mixing distribution in discrete choice models},
  journal = {Transportation Research Part B: Methodological},
  year = {2007},
  volume = {41},
  number = {7},
  pages = {784-794},
  DOI = {10.1016/j.trb.2007.01.002}}}

When using random utility models for a route choice problem, a critical issue is the significant correlation among alternatives. There are basically two types of models proposed in the literature to address it: (i) a deterministic correction of the path utilities in a Multinomial Logit model (such as the Path Size Logit or the C-Logit models) and (ii) an explicit modeling of the correlation through assumptions about the error terms, and the use of advanced discrete choice models such as the Cross-Nested Logit or the Error Component models. The first is simple, easy to handle and often used in practice. Unfortunately, it does not correctly capture the correlation structure, as we discuss in details in the paper. The second is more consistent with the modeling objectives, but very complicated to specify and estimate. The modeling framework proposed in this paper allows the analyst to control the trade-off between the simplicity of the model and the level of realism. Within this framework, the key concept capturing the correlation structure is called a subnetwork. A subnetwork is a simplification of the road network only containing easy identifiable and behaviorally relevant roads. In practice, the subnetwork can easily be defined based on the route network hierarchy. The importance and the originality of our approach lie in the possibility to capture the most important correlation without considerably increasing the model complexity. This makes it suitable for a wide spectrum of applications, namely involving realistic large-scale networks. As an illustration, we present estimation results of a factor analytic specification of a mixture of Multinomial Logit model, where the correlation among paths is captured by error components. The estimation is based on a GPS dataset collected in the Swedish city of Borlänge. The results show a significant increase in model fit and forecasting performance for the Error Component model compared to a Path Size Logit model. Moreover, the correlation parameters are significant.

@Article{FrejBier07,
  author = {Emma Frejinger and Michel Bierlaire},
  title = {Capturing correlation with subnetworks in route choice models},
  journal = {Transportation Research Part B: Methodological},
  year = {2007},
  volume = {41},
  number = {3},
  pages = {363-378},
  DOI = {10.1016/j.trb.2006.06.003}}}

The Quebec City-Windsor corridor is the busiest and most important trade and transportation corridor in Canada. The transportation sector is the second largest contributor to greenhouse gas (GHG) emissions in the country. Governments around the world, including Canada, are considering increased mode share by rail as a way to reduce transportation emissions. To understand whether freight mode shift is a realistic means to reduce transportation emissions, an analytical model is needed that can predict the effect of government policy on mode split. This paper presents the findings of the first such model developed for the Quebec City-Windsor Corridor. The model itself is a stated preference carrier choice model of shippers in this busy corridor. The model was developed using the results of a stated preference survey undertaken in the fall of 2005. The survey was designed explicitly to evaluate shipper preferences for the carriage of intercity consignments, and particularly their preferences for carriers that contract the services of rail companies to carry these shipments via rail. The results of the study show that shippers are very mistrustful of using rail to move their consignments and suggests that increasing rail’s share of freight faces tremendous challenges.

@Article{PattEwinHaid07a,
  author = {Zachary Patterson and Gordon Ewing and Murtaza Haider},
  title = {Shipper Mistrust of Rail Use: First Stated Preference Carrier Choice Survey for the Quebec City - Windsor Corridor},
  journal = {Transportation Research Record},
  year = {2007},
  volume = {2008},
  pages = {67-74},
  DOI = {10.3141/2008-09},
  note = {Accepted on Mar 02, 2007}}}

We address two fundamental issues associated with the use of cross-nested logit models. On the one hand, we justify the adequate normalization of the model proposed by Wen and Koppelman (2001). On the other hand, we provide an analysis of the correlation structure of the CNL, based on random utility theory. We evaluate the validity of the approximation proposed by Papola (2004), both using theoretical arguments and numerical examples based on the exact formula of the correlation.

@Article{AbbeBierTole07,
  author = {Emmanuel Abbe and Michel Bierlaire and Tomer Toledo},
  title = {Normalization and correlation of cross-nested logit models},
  journal = {Transportation Research Part B: Methodological},
  year = {2007},
  volume = {41},
  number = {7},
  pages = {795-808},
  DOI = {10.1016/j.trb.2006.11.006}}}

@Article{HessBierPola07,
  author = {Stephane Hess and Michel Bierlaire and John Polak},
  title = {A systematic comparison of continuous and discrete mixture models},
  journal = {European Transport},
  year = {2007},
  volume = {37},
  pages = {35-61},
  note = {Accepted on Apr 04, 2007}}}

The medical image registration problem can be formulated as a nonlinear programming problem. To identify appropriate algorithms to solve it, it is critical to analyze the properties of the problem. In this paper, we consider the image registration problem based on maximization of mutual information when the partial volume (PV) interpolation is used to update the joint histogram. We identify pathological cases which may happen in practice, and which may lead to discontinuous instances of the objective function. We show that the objective function is not differentiable and that the set of non- differentiability is of null measure. Then, we propose a derivative- free algorithm specially designed for this application. Derivative- free optimization involves all the methods used to minimize an objective function when its derivatives are not available and when the function is expensive. We present here, a trust-region algorithm based on radial basis functions instead of the classical second-order polynomials. Actually, our surrogate of the objective function is a mixed radial and polynomial model. On the instances of the medical image registration problem, our method surpasses all the tested state-of-the-art derivative-free algorithms.

@Article{OeuvBier06-medical,
  author = {Rodrigue Oeuvray and Michel Bierlaire},
  title = {A new derivative-free algorithm for the medical image registration problem},
  journal = {International Journal of Modelling and Simulation},
  year = {2007},
  volume = {27},
  number = {2},
  pages = {115-124},
  DOI = {10.2316/Journal.205.2007.2.205-4367}}}

@Article{OsorWeibPereBierGarn06,
  author = {Carolina Osorio and Christophe Weibel and Pao Perez and Michel Bierlaire and Philippe Garnerin},
  title = {Patient flow simulation as a tool for estimating policy impact},
  journal = {Swiss Medical Informatics},
  year = {2006},
  volume = {58},
  pages = {33-36}}}

We propose a discrete choice framework for pedestrian dynamics, modelling short term behavior of individuals as a response to the presence of other pedestrians. We use a dynamic and individual-based spatial discretization, representing the physical space. We develop a model predicting where the next step of a walking pedestrian will be, at a given point in time. The use of the discrete choice framework is justified by its flexibility, the capacity to deal with individuals and the compatibility with agent-based simulation. The model is calibrated using data from actual pedestrian movements, manually taken from video sequences. We present two different formulations: a cross-nested logit and a mixed nested logit. In order to verify the quality of the calibrated model, we have designed and developed a pedestrians simulator.

@Article{AntoBierWebe06,
  author = {Gianluca Antonini and Michel Bierlaire and Mats Weber},
  title = {Discrete choice models of pedestrian walking behavior},
  journal = {Transportation Research Part B: Methodological},
  year = {2006},
  volume = {40},
  number = {8},
  pages = {667-687},
  DOI = {10.1016/j.trb.2005.09.006}}}

Many complex transportation models can be formulated as fixed-point problems. Typical examples are the “equilibrium-like” models, motivated by the need to capture the interaction between the transport supply (that is, the infrastructure) and transport demand (that is, travelers’ behavior) in various ways. In this paper, we propose a new approach for solving fixed-point problems and, equivalently, systems of nonlinear equations. It is a generalization of secant methods, and uses several previous iterates to generate a linear approximation of the nonlinear function. Although it belongs to the quasi-Newton family of methods, our algorithm is matrix free, allowing it to solve large-scale systems of equations without derivative and without any particular assumption about the structure of the problem or its Jacobian. Computational experiments on standard problems show that this algorithm outperforms classical, large-scale quasi-Newton methods in terms of efficiency and robustness. Its numerical performances are similar to Newton- Krylov methods currently considered as the best algorithms to solve large-scale nonlinear systems of equations. Furthermore, our approach, using multiple previous iterates to build a linear approximation of the nonlinear function, exhibits robust behavior in the presence of noise in the equations, which makes it particularly well adapted to transportation problems. We run our algorithm on a simple origin-destination (OD) matrix estimation problem and on some instances of the consistent anticipatory route guidance (CARG) problem, to illustrate the applicability of the proposed method and to show its significant superiority to the classical method of successive averages (MSA). Regarding size, we were able to solve a CARG problem with more than 120,000 variables. We were also able to solve classical problems with up to two million variables.

@Article{BierCrit06,
  author = {Michel Bierlaire and Frank Crittin},
  title = {Solving noisy large scale fixed point problems and systems of nonlinear equations},
  journal = {Transportation Science},
  year = {2006},
  volume = {40},
  number = {1},
  pages = {44-63},
  DOI = {10.1287/trsc.1050.0119}}}

When vehicle routing problems with additional constraints, such as capacity or time windows, are solved via column generation and branch-and-price, it is common that the pricing subproblem requires the computation of a minimum cost constrained path on a graph with costs on the arcs and prizes on the vertices. A common solution technique for this problem is dynamic programming. In this paper we illustrate how the basic dynamic programming algorithm can be improved by bounded bi-directional search and we experimentally evaluate the effectiveness of the enhancement proposed. We consider as benchmark problems the elementary shortest path problems arising as pricing subproblems in branch-and-price algorithms for the capacitated vehicle routing problem, the vehicle routing problem with distribution and collection and the capacitated vehicle routing problem with time windows.

@Article{RighSala06,
  author = {G. Righini and Matteo Salani},
  title = {Symmetry helps: Bounded bi-directional dynamic programming for the elementary shortest path problem with resource constraints},
  journal = {Discrete Optimization},
  year = {2006},
  volume = {3},
  number = {3},
  pages = {255-273},
  DOI = {10.1016/j.disopt.2006.05.007}}}

The emergence of Intelligent Transportation Systems and the associated technologies has increased the need for complex models and algorithms. Namely, real-time information systems, directly influencing transportation demand, must be supported by detailed behavioral models capturing travel and driving decisions. Discrete choice models methodology provide an appropriate framework to capture such behavior. Recently, the Cross-Nested Logit (CNL) model has received quite a bit of attention in the literature to capture decisions such as mode choice, departure time choice and route choice. %The CNL model is an extension of the Nested Logit model, providing %more flexibility at the cost of some complexity in the model formulation. In this paper, we develop on the general formulation of the Cross Nested Logit model proposed by Ben-Akiva and Bierlaire (1999) and based on the Generalized Extreme Value (GEV) model. We show that it is equivalent to the formulations byby Papola (2004) and Wen and Koppelman (2001). We also show that the formulations by Small(1987) and Vovsha(1997) are special cases of this formulation. We formally prove that the Cross-Nested Logit model is indeed a member of the GEV models family. In doing so, we clearly distinguish between conditions that are necessary to prove consistency with the GEV theory, from normalization conditions. Finally, we propose to estimate the model with non-linear programming algorithms, instead of heuristics proposed in the literature. In order to make it operational, we provide the first derivatives of the log-likelihood function, which are necessary to such optimization procedures.

@Article{Bier06,
  author = {Michel Bierlaire},
  title = { A theoretical analysis of the cross-nested logit model},
  journal = {Annals of Operations Research},
  year = {2006},
  volume = {144},
  number = {1},
  pages = {287-300},
  DOI = {10.1007/s10479-006-0015-x}}}

In this paper we address the problem of detection and tracking of pedestrians in complex scenarios. The inclusion of prior knowledge is more and more crucial in scene analysis to guarantee flexibility and robustness, necessary to have reliability in complex scenes. We aim to combine image processing methods with behavioral models of pedestrian dynamics, calibrated on real data. We introduce Discrete Choice Models (DCM) for pedestrian behavior and we discuss their integration in a detection and tracking context. The obtained results show how it is possible to combine both methodologies to improve the performances of such systems in complex sequences.

@Article{AntoVeneBierThir06,
  author = {Gianluca Antonini and Santiago Venegas and Michel Bierlaire and Jean-Philippe Thiran},
  title = {Behavioral priors for detection and tracking of pedestrians in video sequences},
  journal = {International Journal of Computer Vision},
  year = {2006},
  volume = {69},
  number = {2},
  pages = {159-180},
  DOI = {10.1007/s11263-005-4797-0}}}

Generalised extreme value models provide an interesting theoretical framework to develop closed-form random utility models. Unfortunately, few instances of this family are to be found as operational models in practice. The form of the model, based on a generating function G which must satisfy specific properties, is rather complicated. Fundamentally, it is not an easy task to translate an intuitive perception of the correlation structure by the modeller into a concrete G function. And even if the modeller succeeds in proposing a new G function, the task of proving that it indeed satisfies the properties is cumbersome. In modelling transportation demand, researchers face the problem that many of the choices they wish to model interact in complex ways. One approach to this problem is to use mixed logit models, exploiting the power of simulation-based estimation, to incorporate the interactions required. An alternative approach, however, which is followed in this paper, is to exploit further the GEV model family originally proposed by McFadden [McFadden, D., 1978. Modelling the choice of residential location. In: Karlquist, A. et al. (Eds.), Spatial Interaction Theory and Residential Location. North-Holland, Amsterdam, pp. 75–96]. The main objectives of this paper are (i) to provide a general theoretical foundation, so that the development of new GEV models will be easier in the future, and (ii) to propose an easy way of generating new GEV models without a need for complicated proofs. Our technique requires only a network structure capturing the underlying correlation of the choice situation under consideration. If the network complies with some simple conditions, we show how to build an associated model. We prove that it is indeed a GEV model and, therefore, complies with random utility theory. The multinomial logit, the nested logit and the cross-nested logit models are specific instances of our class of models. So are the recent GenL model, combining choice set generation and choice model and some specialised compound models used in recent transportation work. Probability, expected maximum utility and elasticity formulae for the class of models are provided.

@Article{DalyBier06,
  author = {Andrew Daly and Michel Bierlaire},
  title = {A General and Operational Representation of Generalised Extreme Value Models},
  journal = {Transportation Research Part B: Methodological},
  year = {2006},
  volume = {40},
  number = {4},
  pages = {285-305},
  DOI = {10.1016/j.trb.2005.03.003}}}

The vehicle routing problem with simultaneous distribution and collection (VRPSDC) is the variation of the capacitated vehicle routing problem that arises when the distribution of goods from a depot to a set of customers and the collection of waste from the customers to the depot must be performed by the same vehicles of limited capacity and the customers can be visited in any order. We study how the branch-and-price technique can be applied to the solution of this problem and in particular we compare two different ways of solving the pricing subproblem: exact dynamic programming and state space relaxation. By applying a bidirectional search we experimentally prove its effectiveness in solving the subproblem. We also devise suitable branching strategies for both the exact and the relaxed approach and we report on an extensive set of computational experiments on benchmark instances with both simple and composite demands.

@Article{DellRighSala06,
  author = {M. Dell'Amico and G. Righini and Matteo Salani},
  title = {A Branch-and-Price Approach to the Vehicle Routing Problem with Simultaneous Distribution and Collection},
  journal = {Transportation Science},
  year = {2006},
  volume = {40},
  number = {2},
  pages = {235-247},
  DOI = {10.1287/trsc.1050.0118}}}

@Article{BierThemAxha06,
  author = {Michel Bierlaire and Micha\"el Th\'emans and Kay Axhausen},
  title = {Analysis of driver's response to real-time information in Switzerland},
  journal = {European Transport},
  year = {2006},
  volume = {34},
  pages = {21-41}}}

Transportation literature suggests that men and women have different characteristics with respect to commuting patterns, as well as with respect to their propensity to switch between travel options. In North America, women are expected to have an increasing impact on travel demand. As such, differences in female responses to travel demand management strategies are likely to become increasingly important as governments try to curtail travel demand in the future. This paper uses a 1994 stated preference (SP) survey of suburban commuters in Montreal to: determine whether there is evidence for differences between men and women in the factors that affect work trip choices; quantify those differences; and suggest what these differences imply for travel demand management in the future in Montreal. The main conclusions of this paper are as follows. First, women and men should be modeled separately with respect to work trip mode choice. Second, there are three main differences that appear from the econometric models: women are less likely to choose public transit than men; women are more likely to choose to rideshare; and women are less time sensitive when it comes to commuting than men are.

@Article{PatEwiHai2005,
  author = {Zachary Patterson and Gordon Ewing and Murtaza Haider},
  title = {A Gender-based Analysis of Work Trip Mode Choice of Suburban Montreal Commuters Using Stated Preference Data},
  journal = {Transportation Research Record},
  year = {2005},
  volume = {1924},
  pages = {85-93},
  DOI = {10.3141/1924-11},
  note = {Accepted on Mar 01, 2005}}}

In this paper, we discuss some of the issues that arise with the computation of the implied value of travel-time savings in the case of discrete choice models allowing for random taste heterogeneity. We specifically look at the case of models producing a non-zero probability of positive travel-time coefficients, and discuss the consistency of such estimates with theories of rational economic behaviour. We then describe how the presence of unobserved travel-experience attributes or conjoint activities can bias the estimation of the travel-time coefficient, and can lead to false conclusions with regards to the existence of negative valuations of travel-time savings. We note that while it is important not to interpret such estimates as travel-time coefficients per se, it is nevertheless similarly important to allow such effects to manifest themselves; as such, the use of distributions with fixed bounds is inappropriate. On the other hand, the use of unbounded distributions can lead to further problems, as their shape (especially in the case of symmetrical distributions) can falsely imply the presence of positive estimates. We note that a preferable solution is to use bounded distributions where the bounds are estimated from the data during model calibration. This allows for the effects of data impurities or model misspecifications to manifest themselves, while reducing the risk of bias as a result of the shape of the distribution. To conclude, a brief application is conducted to support the theoretical claims made in the paper.

@Article{HessBierPola05,
  author = {Stephane Hess and Michel Bierlaire and John Polak},
  title = {Estimation of value of travel-time savings using Mixed Logit models},
  journal = {Transportation Research Part A: Policy and Practice},
  year = {2005},
  volume = {39},
  number = {3},
  pages = {221-236},
  DOI = {10.1016/j.tra.2004.09.007}}}

We consider the school bus routing and scheduling problem, where transportation demand is known and bus scheduling can be planned in advance. We present a comprehensive methodology designed to support the decision of practitioners. We first propose a modeling framework where the focus is on optimizing the level of service for a given number of buses, then we describe an automatic procedure generating a solution to the problem. The procedure first builds a feasible solution, which is subsequently improved using a heuristic. We analyze two important issues associated with this methodology. On the one hand, we analyze the performance of three types of heuristics both on real and synthetic data. We recommend the use of a simulated annealing technique exploring infeasible solutions, which performs slightly better than all others. More importantly, we find that the performance of all heuristics is not globally affected by the choice of the parameters. This is important from a practitioner viewpoint, because the fine-tuning of algorithm parameters is not critical for the algorithm’s performance. We have successfully applied our methods on real problems and on large-scale problems. On the other hand, we propose an interactive tool allowing the practitioner to visualize the proposed solution, to test its robustness, and to dynamically rebuild new solutions if the data of the original problem are modified.

@Article{SpadBierLieb05,
  author = {Michela Spada and Michel Bierlaire and Thomas Liebling},
  title = {Decision-aid methodology for the school bus routing and scheduling problem},
  journal = {Transportation Science},
  year = {2005},
  volume = {39},
  number = {4},
  pages = {477-490},
  DOI = {10.1287/trsc.1040.0096}}}

The problem of estimating and predicting Origin-Destination (OD) tables is known to be important and difficult. In the specific context of Intelligent Transportation Systems (ITS), the dynamic nature of the problem and the real-time requirements make it even more intricate. We consider here a least-square modeling approach for solving the OD estimation and prediction problem, which seems to offer convenient and flexible algorithms. The dynamic nature of the problem is represented by an autoregressive process, capturing the serial correlations of the state variables. Our formulation is inspired from Cascetta et al. (1993) and Ashok and Ben-Akiva (1993). We compare the Kalman filter algorithm to LSQR, an iterative algorithm proposed by Paige and Saunders (1982) for the solution of large-scale least-squares problems. LSQR explicitly exploits matrix sparsity, allowing to consider larger problems likely to occur in real applications. We show that the LSQR algorithm significantly decreases the computation effort needed by the Kalman filter approach for large-scale problems. We also provide a theoretical number of flops for both algorithms to predict which algorithm will perform better on a specific instance of the problem.

@Article{BierCrit04,
  author = {Michel Bierlaire and Frank Crittin},
  title = {An efficient algorithm for real-time estimation and prediction of dynamic OD table},
  journal = {Operations Research},
  year = {2004},
  volume = {52},
  number = {1},
  pages = {116-127},
  DOI = {10.1287/opre.1030.0071}}}

@Article{RighSala04,
  author = {G. Righini and Matteo Salani},
  title = {Dynamic programming algorithms for the elementary shortest path problem with resource constraints},
  journal = {Electronic Notes in Discrete Mathematics},
  year = {2004},
  volume = {17},
  pages = {247 - 249},
  DOI = {10.1016/j.endm.2004.03.047}}}

We propose a measure of quality for OD trip tables estimated from link counts. This measure, called the total demand scale is based only on the estimated OD trip table and on the assignment matrix used to estimate it. It is independent of the OD estimation method and of the technique used to overcome the underdetermination of the OD estimation problem. The total demand scale measures the intrinsic underdetermination related to the OD estimation problem, considering only the network topology and the underlying route choice model. Because it identifies the level of arbitrariness introduced by the a priori matrix in the estimation process, our approach helps to evaluate if an important amount of resources must be invested for the a priori matrix, or if the available link counts contains sufficient information. The computation of the total demand scale enables to identify at zero additional cost those OD pairs such that no measurement is available on any path linking them. A MATLAB code for the computation of the total demand scale is also provided.

@Article{Bier02,
  author = {Michel Bierlaire},
  title = {The total demand scale: A new measure of quality for static and dynamic origin-destination trip tables},
  journal = {Transportation Research Part B: Methodological},
  year = {2002},
  volume = {36},
  number = {9},
  pages = {837-850},
  DOI = {10.1016/S0191-2615(01)00036-4}}}

We discuss the development of predictive choice models that go beyond the random utility model in its narrowest formulation. Such approaches incorporate several elements of cognitive process that have been identified as important to the choice process, including strong dependence on history and context, perception formation, and latent constraints. A flexible and practical hybrid choice model is presented that integrates many types of discrete choice modeling methods, draws on different types of data, and allows for flexible disturbances and explicit modeling of latent psychological explanatory variables, heterogeneity, and latent segmentation. Both progress and challenges related to the development of the hybrid choice model are presented.

@Article{BenAMcFaTraiEtal02,
  author = {Moshe Ben-Akiva and Dan McFadden and Kenneth Train and Joan Walker and Chandra Bhat and Michel Bierlaire and Denis Bolduc and Axel Boersch-Supan and David Brownstone and David Bunch and Andrew Daly and Andr\'e {de Palma} and Dinesh Gopinath and Anders Karlstrom and Marcela Munizaga},
  title = {Hybrid choice models: Progress and challenges},
  journal = {Marketing Letters},
  year = {2002},
  volume = {13},
  number = {3},
  pages = {163-175},
  DOI = {10.1023/A:1020254301302}}}

@Article{TordBierDumo02,
  author = {Alexandre Torday and Michel Bierlaire and Andr\'e-Gilles Dumont},
  title = {Seeing the wood and the trees: simulation-based evaluation of the effect of variable speed limit signs on capacity and user safety},
  journal = {Traffic technology international},
  year = {2002},
  volume = {1},
  pages = {60-64}}}

La télématique des transports intéresse les gestionnaires qui voient en elle la solution à plusieurs de leurs problèmes, mais elle est également un thème qui passionne de nombreux chercheurs. Si la plupart des outils développés semblent pouvoir offrir des résultats prometteurs, il faut se garder de céder trop facilement à l'élan d'optimisme qui les accompagne. Ils se basent souvent sur des justifications trop théoriques ou conceptuelles, si ce n'est sur des préjugés trop bien ancrés dans nos esprits. Comme dans tout domaine technique, il paraît audacieux de se passer d'une solide étude d'évaluation avant l'implantation d'un service de télématique, même si l'on est convaincu de son efficacité. Parmi les outils servant à de telles évaluations, les simulateurs de trafic routier peuvent être d'une grande utilité, qu'ils soient macro, méso ou microscopiques. Dans le cadre du projet PAPABILES (Projet autoroutier pilote Aubonne-Belmont pour une initiative lausannoise d'évaluation par simulation), une telle évaluation a été réalisée avec l'appui du service des routes de l'Etat de Vaud. Elle avait pour but de déterminer les effets de l'implantation de panneaux à limitation de vitesses variables (PLVV) sur un tronçon autoroutier fortement chargé, au niveau de sa capacité et de la sécurité des usagers. Pour cela, le cas concret de l'autoroute A 1 entre Aubonne et l'échangeur de Crissier (à l'ouest de Lausanne) a été retenu. En effet, ce tronçon est soumis à des charges de trafic particulièrement importantes, surtout à partir de l'entrée de Morges-est en direction de Lausanne. Dans cette région, le service des routes du canton de Vaud projette d'implanter des panneaux à limitation de vitesse variables.

@Article{TordBierDumo01,
  author = {Alexandre Torday and Michel Bierlaire and Andr\'e-Gilles Dumont},
  title = {Modelling evaluation of impact of variable speed limitation sign posts on road capacity and user safety},
  journal = {Strasse und Verkehr},
  year = {2001},
  volume = {87},
  number = {6},
  pages = {283-286}}}

Advanced Traveler Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS) have the potential to contribute to the solution of the traffic congestion problem. DynaMIT is a real-time system that can be used to generate guidance for travelers. The main principle on which DynaMIT is based is that information should be consistent, and user optimal. Consistency implies that the traffic conditions experienced by the travelers are consistent with the condition assumed in generating the guidance. To generate consistent user optimal information, DynaMIT performs two main functions: state estimation and prediction. A demand simulator and a supply simulator interact to perform these tasks. A case study demonstrates the value of the system.

@Article{BenABierBurtKoutMish01,
  author = {Moshe Ben-Akiva and Michel Bierlaire and Didier Burton and Haris Koutsopoulos and Rabi Mishalani},
  title = {Network state estimation and prediction for real-time transportation management applications},
  journal = {Networks and Spatial Economics},
  year = {2001},
  volume = {1},
  number = {3-4},
  pages = {293-318},
  DOI = {10.1023/A:1012883811652}}}

@Article{DellArenBierBogeTimm98,
  author = {Benedict Dellaert and Theo Arentze and Michel Bierlaire and Alois Borgers and Harry Timmermans},
  title = {Investigating consumers' tendency to combine multiple shopping purposes and destinations},
  journal = {Journal of Marketing Research},
  year = {1998},
  volume = {35},
  number = {2},
  pages = {177-188},
  DOI = {10.2307/3151846}}}

@Article{BierLotaToin97,
  author = {Michel Bierlaire and Tsippy Lotan and Philippe Toint},
  title = { On the overspecification of multinomial and nested logit models due to alternative specific constants},
  journal = {Transportation Science},
  year = {1997},
  volume = {31},
  number = {4},
  pages = {363-371},
  DOI = {10.1287/trsc.31.4.363}}}

This article proposes an improvement of existing methods of origin-destination matrix estimation by an explicit use of data describing the structure of the matrix. These data can be obtained from parking surveys. The new model is applied on both illustrative and real examples, and the results are discussed. Comparisons with the results obtained with SATURN/ME2 and the generalized least-squares method are also presented.

@Article{BierToin95,
  author = {Michel Bierlaire and Philippe Toint},
  title = {MEUSE: an origin-destination estimator that exploits structure},
  journal = {Transportation Research Part B: Methodological},
  year = {1995},
  volume = {29},
  number = {1},
  pages = {47-60},
  DOI = {10.1016/0191-2615(94)00025-U}}}

@Article{Bier91,
  author = {Michel Bierlaire},
  title = {Evaluation de la demande en trafic : quelques m\'ethodes de distribution},
  journal = {Annales de la Soci\'et\'e Scientifique de Bruxelles},
  year = {1991},
  volume = {105},
  number = {1-2},
  pages = {17-66}}}

Three new iterative methods for the solution of the linear least squares problem with bound constraints are presented and their performance analyzed. The first is a modification of a method proposed by Lötstedt, while the two others are characterized by a technique allowing for fast active set changes, resulting in noticeable improvements in the speed with which constraints active at the solution are identified. The numerical efficiency of those algorithms is experimentally studied, with particular emphasis on the dependence on the starting point and the use of preconditioning for ill-conditioned problems.

@Article{BierToinTuyt91,
  author = {Michel Bierlaire and Philippe Toint and Daniel Tuyttens},
  title = {On iterative algorithms for linear least squares problems with bound constraints},
  journal = {Linear Algebra and its Applications},
  year = {1991},
  volume = {143},
  number = {1},
  pages = {111-143},
  DOI = {10.1016/0024-3795(91)90009-L}}}