Nos publications et articles scientifiques !
Articles scientifiques
Abstract: : Long-distance (LD) or intercity travel is getting less attention by researchers than usual daily trips. There is no specific definition for this kind of trip at the national, provincial, and inter-regional levels. At the same time, it has a high contribution to transportation in terms of distance travelled. This paper presents a model comparison method for (LD) trip generation model for LD trips performed by residents of Canada. The terms of « long-distance » trip based on Travel Survey for Residents in Canada (TSRC) survey is considered as non-frequent overnight and day trip. This study compared several machine learning methods for the trip generation model. Since LD trip is relatively rare, the data set of TSRC is considered imbalanced data, three different techniques on the data preparation level as part of rare event modelling (over, under, and synthetically oversampling) employed to handle the issue of imbalanced data. TSRC data from 2012 to 2017 was used for model estimation. Among the random forest, CART, CTree, and logit models, it was found that the random forest has the best performance in prediction, and decision tree models have the best overall accuracy. Also, Income level and educational level play an essential role in the occurrence of an intercity trip. The paper highlights the importance of improvement in intercity travel survey methods and other data collection methods.
Abstract: : Car ownership is linked to higher car use, which leads to important environmental, social and health consequences. As car ownership keeps increasing in most countries, it remains relevant to examine what factors and policies can help contain this growth. This paper uses an advanced spatial econometric modeling framework to investigate spatial dependences in household car ownership rates measured at fine geographical scales using administrative data of registered vehicles and census data of household counts for the Island of Montreal, Canada. The use of a finer level of spatial resolution allows for the use of more explanatory variables than previous aggregate models of car ownership. Theoretical considerations and formal testing suggested the choice of the Spatial Durbin Error Model (SDEM) as an appropriate modeling option. The final model specification includes sociodemographic and built environment variables supported by theory and achieves a Nagelkerke pseudo-R2 of 0.93. Despite the inclusion of those variables the spatial linear models with and without lagged explanatory variables still exhibit residual spatial dependence. This indicates the presence of unobserved autocorrelated factors influencing car ownership rates. Model results indicate that sociodemographic variables explain much of the variance, but that built environment characteristics, including transit level of service and local commercial accessibility (e.g., to grocery stores) are strongly and negatively associated with neighborhood car ownership rates. Comparison of estimates between the SDEM and a non-spatial model indicates that failing to control for spatial dependence leads to an overestimation of the strength of the direct influence of built environment variables.
Abstract: Travel information has the potential to influence travellers choices, in order to steer travellers to less congested routes and alleviate congestion. This paper investigates, on the one hand, how travel information affects route choice behaviour, and on the other hand, the impact of the travel time representation on the interpretation of parameter estimates and prediction accuracy. To this end, we estimate recursive models using data from an innovative data collection effort consisting of route choice observation data from GPS trackers, travel diaries and link travel times on the overall network. Though such combined data sets exist, these have not yet been used to investigate route choice behaviour. A dynamic network in which travel times change over time has been used for the estimation of both recursive logit and nested models. Prediction and estimation results are compared to those obtained for a static network. The interpretation of parameter estimates and prediction accuracy differ substantially between dynamic and static networks as well as between models with correlated and uncorrelated utilities. Contrary to the static results, for the dynamic, where travel times are modelled more accurately, travel information does not have a significant impact on route choice behaviour. However, having travel information increases the travel comfort, as interviews with participants have shown.
Abstract: Continuous household travel surveys have been identified as a potential replacement for traditional one-off cross-sectional surveys. Many regions around the world have either replaced their traditional cross-sectional survey with its continuous counterpart, or are weighing the option of doing so. The main claimed advantage of continuous surveys is the availability of data over a continuous spectrum of time, thus allowing for the investigation of the temporal variation in trip behavior. The objective of this paper is to put this claim to the test: Can continuous household travel surveys capture the temporal variation in trip behavior? This claim can be put to the test by estimating mixed effects models on the individual, household, spatial and modal level using date stemming from the Montreal Continuous Survey (2009–2012). A mixed effects model (also know as a hierarchical or multilevel model) respects the hierarchical design of a household survey by nesting or crossing entities where necessary. The use of a mixed effects econometric framework allows for partitioning the variance of the dependent variable to a set of grouping factors, strengthening the understanding of the underlying causes of variation in travel behavior. The findings of the paper conclude that the temporal variability in trip behavior is only observed when modelling on the regional level. Further, the study suggests that a large proportion of the variance of trip behavior is attributed to different grouping factors, such as region or municipal sector for regional trip behavior models.
Abstract: Evolutionary algorithms have been used extensively over the past 2 decades to provide solutions to the Transit Network Design Problem and the Transit Network and Frequencies Setting Problem. Genetic algorithms in particular have been used to solve the multi-objective problem of minimizing transit users’ and operational costs. By finding better routes geometry and frequencies, evolutionary algorithms proposed more efficient networks in a timely manner. However, to the knowledge of the authors, no experimentation included precise and complete pedestrian network data for access, egress and transfer routing. Moreover, the accuracy and representativeness of the transit demand data (Origin Destination matrices) are usually generated from fictitious data or survey data with very low coverage and/or representativity. In this paper, experiments conducted with three medium-sized cities in Quebec demonstrate that performing genetic algorithm optimizations using precise local road network data and representative public transit demand data can generate plausible scenarios that are between 10 and 20% more efficient than existing networks, using the same parameters and similar fleet sizes.
Abstract: A better understanding of mobility behaviors is relevant to many applications in public transportation, from more accurate travel demand models to improved supply adjustment, customized services and integrated pricing. In line with this context, this study mined 51 weeks of smart card (SC) data from Montréal, Canada to analyze interpersonal and intrapersonal variability in the weekly use of public transit. Passengers who used only one type of product (AP − annual pass, MP − monthly pass, or TB − ticket book) over 12 months were selected, amounting to some 200,000 cards. Data was first preprocessed and summarized into card-week vectors to generate a typology of weeks. The most popular weekly patterns were identified for each type of product and further studied at the individual level. Sequences of week clusters were constructed to represent the weekly travel behavior of each user over 51 weeks. They were then segmented by type of product according to an original distance, therefore highlighting the heterogeneity between passengers. Two indicators were also proposed to quantify intrapersonal regularity as the repetition of weekly clusters throughout the weeks. The results revealed MP owners have a more regular and diversified use of public transit. AP users are mainly commuters whereas TB users tend to be more occasional transit users. However, some atypical groups were found for each type of product, for instance users with 4-day work weeks and loyal TB users.
Abstract: We use data from the Swiss national household travel survey to 1. analyze the socioeconomic determinants for intermodal travel in Switzerland and 2. estimate a first large-scale multimodal recursive logit route choice model for urban trip making. We show that intermodal travel is mostly associated with ownership of transit subscriptions, which allow free at the point-of-use public transportation. We also present a framework using open-source data to generate the multimodal network for the recursive logit model estimation. The fact that the model only needs a multimodal network to model the transport supply makes it independent of path sampling algorithms for the choice-set construction and it thus provides an alternative to classic mode and route choice models, since it can estimate mode and route choice parameters with directly observed routes, removing the sampling bias. By eliminating the need to sample alternative paths for estimation, it also simplifies the estimation process, making it a viable choice as an integral solution for joint route and mode choice modelling.
Abstract: Representing activity-travel scheduling decisions as path choices in a time–space network is an emerging approach in the literature. In this paper, we model choices of activity, location, timing and transport mode using such an approach and seek to estimate utility parameters of recursive logit models. Relaxing the independence from irrelevant alternatives (IIA) property of the logit model in this setting raises a number of challenges. First, overlap in the network may not fully characterize perceptual correlation between paths, due to their interpretation as activity schedules. Second, the large number of states that are needed to represent all possible locations, times and activity combinations imposes major computational challenges to estimate the model. We combine recent methodological developments to build on previous work by Blom Västberg et al. (2016) and allow to model complex and realistic correlation patterns in this type of network. We use sampled choices sets in order to estimate a mixed recursive logit model in reasonable time for large-scale, dense time-space networks. Importantly, the model retains the advantage of fast predictions without sampling choice sets. In addition to estimation results, we present an extensive empirical analysis which highlights the different substitution patterns when the IIA property is relaxed, and a cross-validation study which confirms improved out-of-sample fit.
Mémoires et thèses
Résumé : Cette thèse porte sur la modélisation du trafic dans les réseaux routiers et comment celle-ci est intégrée dans des modèles d’optimisation. Ces deux sujets ont évolué de manière plutôt disjointe: le trafic est prédit par des modèles mathématiques de plus en plus complexes, mais ce progrès n’a pas été incorporé dans les modèles de design de réseau dans lesquels les usagers de la route jouent un rôle crucial. Le but de cet ouvrage est d’intégrer des modèles d’utilités aléatoires calibrés avec de vraies données dans certains modèles biniveaux d’optimisation et ce, par une décomposition de Benders efficace. Cette décomposition particulière s’avère être généralisable par rapport à une grande classe de problèmes communs dans la littérature et permet d’en résoudre des exemples de grande taille. Le premier article présente une méthodologie générale pour utiliser des données GPS d’une flotte de véhicules afin d’estimer les paramètres d’un modèle de demande dit recursive logit. Les traces GPS sont d’abord associées aux liens d’un réseau à l’aide d’un algorithme tenant compte de plusieurs facteurs. Les chemins formés par ces suites de liens et leurs caractéristiques sont utilisés afin d’estimer les paramètres d’un modèle de choix. Ces paramètres représentent la perception qu’ont les usagers de chacune de ces caractéristiques par rapport au choix de leur chemin. Les données utilisées dans cet article proviennent des véhicules appartenant à plusieurs compagnies de transport opérant principalement dans la région de Montréal. Le deuxième article aborde l’intégration d’un modèle de choix de chemin avec utilités aléatoires dans une nouvelle formulation biniveau pour le problème de capture de flot de trafic. Le modèle proposé permet de représenter différents comportements des usagers par rapport à leur choix de chemin en définissant les utilités d’arcs appropriées. Ces utilités sont stochastiques ce qui contribue d’autant plus à capturer un comportement réaliste des usagers. Le modèle biniveau est rendu linéaire à travers l’ajout d’un terme lagrangien basé sur la dualité forte et ceci mène à une décomposition de Benders particulièrement efficace. Les expériences numériques sont principalement menées sur un réseau représentant la ville de Winnipeg ce qui démontre la possibilité de résoudre des problèmes de taille relativement grande.
Le troisième article démontre que l’approche du second article peut s’appliquer à une forme particulière de modèles biniveaux qui comprennent plusieurs problèmes différents. La décomposition est d’abord présentée dans un cadre général, puis dans un contexte où le second niveau du modèle biniveau est un problème de plus courts chemins. Afin d’établir que ce contexte inclut plusieurs applications, deux applications distinctes sont adaptées à la forme requise: le transport de matières dangereuses et la capture de flot de trafic déterministe. Une troisième application, la conception et l’établissement de prix de réseau simultanés, est aussi présentée de manière similaire à l’Annexe B de cette thèse.
Mots-clés : données GPS, choix de chemin, modèles récursifs de choix, terminaux inter-modaux, capture de flot, décomposition de Benders, optimisation biniveau, maximisation d’utilité aléatoire.
Résumé : Le transport au Québec est responsable en grande partie des émissions de gaz à effet de serre dans l’atmosphère. Une meilleure planification des services de transport en commun et actifs pourrait permettre la diminution de ceux-ci en favorisant un transfert modal au détriment de l’automobile. Cependant, la première étape consiste à effectuer un diagnostic de la situation et comprendre où se situent les lacunes du système. Dans la littérature, il existe de nombreuses méthodes telles des enquêtes ou des études d’indicateurs directs de service ou encore des études spatiales pour effectuer un bilan des services fournis. Un outil prometteur pour comprendre la structure spatio-temporelle de l’offre et de la demande de transport est Traclus_DL, « Trajectory Clustering for Desired lines » qui s’appuie sur le concept de corridors.
Mots-clés : Modèles de choix d’itinéraire récursifs, Modèle markovien d’équilibre de trafic, Estimation par maximum de vraisemblance, Programmation dynamique, Réseaux multi-modaux, Recursive route choice models, Maximum likelihood estimation, Dynamic programming, Multi-modal route choice, Markovian traffic assignment model, Activity-based travel demand.
Résumé : L’achalandage des réseaux de transport en commun varie en fonction de nombreux paramètres. Des facteurs exogènes tels que la météo sont souvent rapportés dans la littérature mais il existe aussi des facteurs individuels : en effet, chaque usager a une utilisation temporelle et spatiale du transport en commun qui lui est propre. D’une part, des différences sont visibles entre les individus. Cette variabilité interpersonnelle est particulièrement prononcée dans les réseaux qui desservent un grand nombre de personnes du fait de la grande hétérogénéité des comportements observés.