Sylvain Lassarre

Sylvain Lassarre
Gustave Eiffel University · Génie des Réseaux de Transports Terrestres et Informatique Avancée (GRETTIA)

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69
Publications
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1,067
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Publications

Publications (69)
Chapter
Full-text available
AdaptiveTordeux, AntoineLebacque, Jean-PatrickLassarre, Sylvain cruise control (ACC) systems are fundamental components of driving automation. At the upper control levelUpper and Lower Control Level, ACC systems are based on car-following models determining the acceleration rate of a vehicle according to the distance gap to the predecessor and the...
Article
Full-text available
Stop-and-go waves are commonly observed in traffic and pedestrian flows. In most microscopic traffic models, they occur through a phase transition and instability of the homogeneous solution after fine tuning of parameters. Inertia effects are believed to play an important role in this mechanism. In this article, we present a novel explanation for...
Preprint
Full-text available
Stop-and-go waves are commonly observed in traffic and pedestrian flows. In most traffic models they occur through a phase transition after fine tuning of parameters when the model has unstable homogeneous solutions. Inertia effects are believed to play an important role in this mechanism. Here, we present a novel explanation for stop-and-go waves...
Chapter
Stop-and-go waves are commonly observed in traffic and pedestrian flows. In traffic theory, they are described by phase transitions of metastable models. The self-organisation phenomenon occurs due to inertia mechanisms but requires fine tuning of the parameters. Here, a novel explanation for stop-and-go waves based on stochastic effects is present...
Article
Full-text available
Stop-and-go waves are commonly observed in traffic and pedestrian flows. In traffic theory they are described by phase transitions of metastable models. The self-organization phenomenon occurs due to inertia mechanisms but requires fine tuning of the parameters. Here, a novel explanation for stop-and-go waves based on stochastic effects is presente...
Article
Full-text available
Human factors related to pedestrians have received somewhat less attention in the literature compared to other road users, although it is often underlined that road and traffic factors appear to explain only a small part of pedestrian walking and crossing behaviour in urban areas. The understanding of pedestrian behaviour in urban areas may assist...
Article
Full-text available
This paper presents analyses of how the economic recession that started in 2008 has influenced the number of traffic fatalities in OECD countries. Previous studies of the relationship between economic recessions and changes in the number of traffic fatalities are reviewed. Based on these studies, a causal diagram of the relationship between changes...
Article
Full-text available
The objective of this research is the comparative analysis of observed and declared behaviour of pedestrians as regards road crossing in urban areas. A field survey was carried out, in which a panel of 75 young and middle-aged pedestrians (out of which 40 males) were asked to take 8 short walking trips (each one corresponding to a different walking...
Chapter
Full-text available
Many car-following models have been developed for jam avoidance in highways. Two mechanisms are used to improve the stability: feedback control with autonomous models and increasing of the interaction within cooperative ones. In this paper, we compare the linear autonomous and collective optimal velocity (OV) models. We observe that the stability i...
Article
Modeling road safety development can provide important insight into policies for the reduction of traffic fatalities. In order to achieve this goal, both the quantifiable impact of specific parameters, as well as the underlying trends that cannot always be measured or observed, need to be considered. One of the key relationships in road safety link...
Article
The objective of this research is the development of pedestrian crossing choice models on the basis of road, traffic and human factors. For that purpose, a field survey was carried out, in which a panel of 75 pedestrians were asked to take 8 short walking trips (each one corresponding to a different walking and crossing scenario) in the Athens city...
Article
Many car-following models are developed for jam avoidance in highways. Two mechanisms are used to improve the stability: feedback control with autonomous models and increasing of the interaction within cooperative ones. In this paper, we compare the linear autonomous and collective optimal velocity (OV) models. We observe that the stability is sign...
Article
This study analyzed road, traffic, and human factors of pedestrian crossing behavior through the development of integrated choice and latent variables models. The analysis used recent research as a starting point, in which a two-stage approach was successfully tested, including a separate estimation of human factors and choice models. Data from a d...
Article
Full-text available
This article proposes a batch-mode algorithm to handle the large databases generated from experimentations using probe vehicles. This algorithm can locate raw Global Positioning System (GPS) positions on a map, but can also be used to correct map-matching errors introduced by real time map-matching algorithms. For each journey, the algorithm global...
Article
The quantitative analysis of international data on road accidents reveals robust differences in road risk. An eloquent case is between France and Great Britain. The ratio of the French to the British mortality risk per vehicle-kilometre has remained approximately equal to two for the last 50 years. In this paper we explore this gap in two steps. Fi...
Article
In this paper a unified methodology is presented for the modelling of the evolution of road safety in 30 European countries. For each country, annual data of the best available exposure indicator and of the number of fatalities were simultaneously analysed with the bivariate latent risk time series model. This model is based on the assumption that...
Article
The objective of this paper is the analysis of the state of the art in pedestrian simulation models and the identification of key issues for further research, with particular focus on the modelling of pedestrians and motorised traffic. A review and a comparative assessment of pedestrian simulation models are carried out, including macroscopic model...
Conference Paper
Full-text available
A new Optimal Velocity (OV) car-following model is defined and explored. The model is solely based on an optimal speed function and a reaction time, and, oppositely to classical OV models, is intrinsically collision-free. If the model has uniform solutions, kink-antikink and soliton stop-and-go patterns can be described with a linear bounded optima...
Article
Full-text available
The paper presents the main aspects of a stochastic conservative model of the evolution of the number of vehicles per road section. The model, defined in continuous time on a discrete space, follows a misanthrope Markovian process. It is a mesoscopic traffic model in the following sense: the vehicles are individually considered, but their dynamics...
Article
The analysis of spatial dependences among road safety outcomes (road accidents and fatalities) has received increased attention in recent research with interesting findings at national or European level. The objective of this research is the modelling of the spatial variation of road accidents and fatalities in Greece. Greece is selected as a count...
Article
Full-text available
The objective of this paper is to develop a comprehensive synthesis on current challenges and opportunities for the assessment of the effectiveness of road safety measures worldwide, with focus on the potential for transferability. This synthesis comprises the preliminary results of the work carried out in the framework of the on-going Working Grou...
Article
Full-text available
The evolution of a line of vehicles on a ring is modeled by means of first-order car-following models. Three generic models describe the speed of a vehicle as a function of the spacing ahead and the speed of the predecessor. The first model is a basic one with no delay. The second is a delayed car-following model with a strictly positive parameter...
Article
A pedestrian trip is a spatiotemporal process going through different states and related to different decisions made at certain times and locations on the urban network. The analysis of pedestrian trips in terms of crossing patterns is a complex task, which is often further limited by a lack of appropriate and detailed data. The objective of this r...
Conference Paper
Full-text available
We study the stationary properties of a microscopic traffic flow model related to a continuous time mass transport process. It is a stochastic collision-free mapping of a classical deterministic first order car-following model calibrated by the targeted speed function and the driver reaction time. The stationary states of the model are analytically...
Article
Full-text available
We propose to study the emergence of kinematic waves in microscopic models of traffic flow. The vehicles motion is given by car-following differential systems that incorporate a targeted state function and a strictly positive reaction time. Through simulations, we observe two types of stationary state for a line of vehicle evolving on a ring: a hom...
Conference Paper
Full-text available
Speeding on the roads is acknowledged as a serious societal and public health issue in all countries. During the last twenty years, much research has been devoted to studying the potential impact of new driver support system, such as Intelligent Speed Adaptation (ISA) systems for contributing to solve this issue. The aim of this paper is to present...
Article
Very considerable advances have been made in road safety over the long term and especially in the recent years. This improvement was achieved in part due to the effectiveness of French decision-making system, even if it remained very perfectible. An analysis of the road safety management system is carried out in order to understand the strengths an...
Article
Full-text available
We intend to define a continuous car-following model exclusively based on the time gap. A model of the interaction between a vehicle and its predecessor is produced by adjusting the time gap to a targeted safety time that is a function of speed. The model is defined by a differential system, to which a consistent numerical scheme is associated. The...
Conference Paper
Full-text available
The zero-range model is a stochastic process of jumps in which some particles evoluate on a discrete space, whose invariant asymptotic distributions are known. The model can be used as a microscopic traffic flow modelling tool for which the speed of each vehicle is a function of the distance from the preceding vehicle. In the model proposed, the ve...
Book
This book covers several research fields, all of which deal with transport. Three main topics are treated: road traffic, granular matter, and biological transport. Different points of view, i.e. modelling, simulations, experiments, and phenomenological observations, are considered. Sub-topics include: highway or urban vehicular traffic (dynamics of...
Article
Road accidents are the tenth leading cause of premature death worldwide and, based on current trends, are likely to become the third leading cause of disability-adjusted life years lost by 2020. Road mortality varies in time and space both between countries and also between regions within the same country. Identifying and understanding the backgrou...
Article
Full-text available
An agent-based model - SAMU - has been designed, which allows exploring pedestrians-drivers interaction in a virtual urban environment. Complex dynamics are obtained from simple behaviours. The key elements of SAMU are presented and discussed.
Article
Road accident outcomes are traditionally analyzed at state or road network level due to a lack of aggregated data and suitable analytical methods. The aim of this paper is to demonstrate usefulness of a simple spatiotemporal modeling of road accident outcomes at small-scale geographical level. Small-area spatiotemporal Bayesian models commonly used...
Article
Pedestrians are mainly exposed to the risk of road accident when crossing a road in urban areas. Traditionally in the road safety field, the risk of accident for pedestrian is estimated as a rate of accident involvement per unit of time spent on the road network. The objective of this research is to develop an approach of accident risk based on the...
Article
This paper presents the potential safety benefits of the experimental French LA VIA Intelligent Speed Adaptation system, according to road network and system mode, based on observed driving speeds, distributions of crash severity and crash injury risk. Results are given for car frontal and side impacts that together, represent 80% of all serious an...
Article
Contingent valuation of a non-fatal road accident This paper reports the results of the first injuries valuation of non fatal road accidents in France. Using the contingent valuation method, estimates of what respondents would pay to avoid one of five injury categories are obtained from the MARC survey. The survey was administred by face-to-face in...
Article
This paper reports the results of the first injuries valuation of non fatal road accidents in France. Using the contingent valuation method, estimates of what respondents would pay to avoid one of five injury categories are obtained from the MARC survey. The survey was administred by face-to-face interview to a representative sample of young French...
Article
En France, la mortalité routière a atteint un pic en 1972 (18 000 morts cette année-là), puis baissé jusqu’à 5 500 morts en 2005, le déclin étant plus ou moins régulier en fonction des mesures prises en faveur de la sécurité routière. Parmi les différents facteurs, les limitations de vitesse et l’obligation de port de la ceinture (1972), puis la po...
Chapter
Agent-based and cellular automata models have been widely used in an efficient and effective way for studying granular traffic, but rarely considering the combined effect and interactions of pedestrians and vehicles in urban networks. So from this point of view an attempt has been made to develop a virtual urban environment which considers both veh...
Article
Full-text available
We present an application of duration models to data from a contingent valuation survey eliciting willingness-to-pay to avoid a non fatal road accident. This survey was concerned with young French drivers, with different social characteristics and driving behaviour. While some drivers accept to contribute, other people choose to pay nothing. The ap...
Article
Full-text available
This paper provides a survey on studies that analyze the macroeconomic effects of intellectual property rights (IPR). The first part of this paper introduces different patent policy instruments and reviews their effects on R&D and economic growth. This part also discusses the distortionary effects and distributional consequences of IPR protection a...
Article
Full-text available
Cet article présente une application de modèles de durée à des données issues d'une enquête contingente dont le but est d'estimer la valeur monétaire de plusieurs scénarii accidentels. De jeunes automobilistes français, avec des caractéristiques sociales et surtout des habitudes de conduite différentes, révélent leur consentement à payer (CAP) pour...
Article
Full-text available
L'évaluation du LAVIA porte sur quatre dimensions qui sont classiques dans l'évaluation d'un produit : l'utilisabilité, l'utilité, l'acceptabilité et la sécurité. Nous donnons les définitions de ces quatre dimensions et présentons les dispositifs d'enquêtes, de mesures et d'observations qui ont été mis en oeuvre pour les évaluer. Les résultats des...
Article
The paper analyses the geographical pattern(s) of road mortality in western Europe for three standard levels of data aggregation. A new adjusted road mortality ratio is proposed. Unlike most mortality ratios, the standardization uses population density rather than age and sex. The hypothesis to be tested is that changes in the level of spatial aggr...
Article
Classic models for the long-term forecasting of the number of fatalities in road accidents are based on a decreasing exponential form of the rate of fatalities per vehicle x km. We decided to extend this simple model to incorporate intervention functions connected with the major safety measures introduced and to replace the deterministic trend by a...
Article
To assess the best routes for the transport of dangerous goods in an area of 600 km[sup 2] in France, software based on a geographical information system was developed to manage, treat, and represent statistical and geographical data related to the evaluation of the risk of transport on a road network. The probability of an accident and release is...

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