Analyse de la prise en compte de la sécurité routière dans les plans de déplacements urbains

At the time when Urban Travel Plans (utps) are being introduced it is important to see how they take safety into account, certu's analysis of a dozen recent docuements shows the position occupied by road safety in utps, reveals the stated aims of the utps, identifies local actions aimed at improving road safety and highlights current or foresedable problems in the implementation of utps. The analysis shows that the way safety is taken into account varies considerably from one city to another. The desire to introduce measures to improve safety is usually present, but there is uncertainty as to how to tackle the issue. The examples of methods and actions that are given in this paper may provide some ideas which merit further examination for utps in the future. It is already obvious that utps will be responsible for profound changes in urban travel and its safety, and the results obtained over the next five years will doubtless have important consequences for the cities of tomorrow.     

L'influence de la biactivité sur les stratégies spatiales des ménages

A survey conducted among staff at the University of Paris xii Val-de-Marne has shown that there are considerable differences in residential location and commuting strategies between those in one income households and those in two income households. This difference varies depending on social group. In the case of higher social groups, being in a two income household as opposed to a one income household increases the range of residential possibilities rather than the household's income per consumer unit, and in particular allows them to live nearer their work. In contrast, for low income groups, working couples commute considerably greater distances than persons in one income households. Thus, for lower income groups, belonging to a working couple mainly provides greater opportunities for home ownership, as an increase in distances to work does not affect journey times.     

Fusion de données pour l'estimation des temps de parcours via la théorie de l'évidence

The emergence of new information technologies and the transformation that has occurred in traffic management have both increased drivers' already considerable need for road traffic information. The travel time is one of the forms in which this information is presented, and a number of systems are based on its dissemination. In this context, this indicator is used as a measure of the impedance (or cost) of routes on the network and/or a congestion indicator. This raises the problem of estimating travel times with an acceptable degree of accuracy, which is a particularly difficult task in urban areas as a result of difficultes of a theoretical, technical and methodological nature. Thus, in order to find out the traffic conditions that prevail on an urban road, the traffic sensors that are usually used to measure traffic conditions are ineffective under certain circumstances. New measurement devices (cameras, GPS or cellphone tracking, etc.) mean that other sources of data are increasingly used in order to supplement the information provided by conventional measurement techniques and improve the accuracy of travel) time estimates. As a result, travel time estimation becomes a typical data fusion problem. This study deals with a multisource estimate of journey times and attempts to provide a comprehensive framework for the utilization of multiple data and demonstrate the feasibility of a travel time estimation system based on the fusion of data of several different types. In this case two types of data are involved, data from conventional induction loop sensors (essentially flow and occupancy measurements) and data from probe vehicles. The selected modelling framework is the Dempster-Shafer Evidence Theory, which has the advantage of being able to take account of both the imprecision and uncertainty of the data. The implementation of this methodology has demonstrated that, in each case, better results are achieved with fusion than with methods based on a single source of data and that the quality of the information, as measured by correctly classified rates, improves as the degree of precision required of the estimate is increased.     

Détection de chutes de personnes sur les voies et d'intrusions en tunnels dans les transports publics

In the framework of the European cromatica project, which aims to improve public transport safety, we have developed a computer vision application for detecting persons or objects falling onto the tracks or non-authorized persons intruding into tunnels when trains are running. The study includes the creation of a demonstrator. Currently, most metro systems have no video coverage of sensitive zones such as platform/track interfaces, tracks and tunnel entrances. When such coverage has been installed, use of the images merely involves the operator observing sensitive zones on an occasional basis, in particular when informed about an incident by other means. In contrast, we propose a completely automatic system based on permanent video monitoring of platform/track interfaces, tracks and tunnel entrances. A first algorithm, built into a processing board in a pc, processes video images in order to detect movement in prohibited zones. Then other algorithms localize this movement and measure the size of the object. The decision whether or not to alert the operator is then taken. The first results from the demonstrator, which has been installed at the Paris Metro station Havre-Caumartin, are very encouraging.     

Quelles interactions entre les marchés de la mobilité à courte et à longue distance ?

This paper proposes a comprehensive quantitative approach to travel analysis that considers personal travel practices with regard to three travel market segments: local weekday travel, local weekend travel and long-distance travel. The first section consists of an evaluation of the overall size of these segments and demonstrates the increasing importance of long-distance travel. Each market segment and then travel as a whole are then analyzed according to individuals’ position in the life cycle, residential location and income level. Last, the roles of location and income in the creation of travel demand in the different segments are then investigated for individuals in the middle part of the life cycle. In particular, it is demonstrated that weekend and weekday travel do not compensate for one another, but there are significant interactions between both local and long-distance travel, and, in particular, residential location.     

Détection de stationnarités anormales dans les couloirs du métro

One of the factors which discourages use of public transport is the feeling of insecurity. In order to overcome this, the operators of metro networks are attempting to find techniques to detect more incidents or anomalies rapidly. It is within this framework, as part of the European cromatica project, that research has been undertaken at inrets by the video team in the Traffic Analysis and Control Department (dart). This paper will concentrate on the detection of abnormal stationarities in metro corridors. Operators wish to identify events of this type as a prolonged stationarity may denote the presence of a drug pusher, an illicit vendor, a thief watching a potential victim, a homeless person, a person suffering from illness, a person who has had a fall, or an abandoned object. The paper firstly gives an account of the developed system and its context and then describes the image processing techniques which have been used. The results obtained with real complex situations are then presented.     

Impact de la tarification,des fréquences et des temps de transfort sur les flux ferroviares dans le Bassin parisien

We have modelled trips on the Paris basin on the basis of the SNCF long-distance surveys. This modelling allows us to test the impact of pricing, journey times and train frequencies on rail travel demand. Three models have been constructed — a generation model (which computes trip production, that is to say the distribution of trips on the basis of the zones in which rail users reside), a geographical distribution model which is used to estimate the distribution of trip production on the basis of origin and destination zone, and lastly a model choice model which computes the proportion of commuting flows which takes place by rail. In this study the generation model has been partially supplied by the surveys. The distribution model takes thetrip production data output from the generation model in order to evaluate the total of rail flow on each O-D pair. This data is then used to calibrate the modal choice model.     

Prospective de la mobilité en Île-de-France Les apports et les limites d' une démarche économétrique

The author has used econometric equations to forecast travel by car and public transport in the Paris Region in the year 2020. The parameters of the equations were estimated on the basis of the observed trends since 1980. The technique is innovative in that it takes account of changes in structural factors (distribution of population by age, ring zone of residence and car ownership) using what are termed structural demand variables. Existing forecasts of these structural factors have been used. By applying hypotheses about changes in the remaining explanatory variables (income, transport price and supply) we have estimated traffic levels in a business as usual scenario whose sensitivity to the explanatory factors has also been tested. From this we have derived some additional indicators: network congestion, trip frequencies for each mode, travel time and aggregate quality indicators. Finally, some limits of this approach are discussed.     

Quelle place pour la sécurité routière dans les plans de déplacements urbains? Entre intégration et diffusion,le cas du plan de déplacements urbains de Lille métropole

This paper describes the position given to road safety in Urban Travel Plans by analyzing Urban Travel Plan document from eleven cities and undertakes a more in-depth investigation of road safety in the Urban Community of Lille. These plans provide an opportunity to disseminate knowledge about road safety to the other areas of urban management. They also describe the beginning of an integration of road safety in urban planning, even if intersectoral approaches at city level have yet to be developed and even if, in the case of Lille, the division of institutional competence with regard to the management of public space still requires clarification.     

L'information sur les durées de parcours: Modélisation de l’activité cognitive impliquée

In recent years some urban express roads have been equipped with journey time information systems, which are greatly appreciated by drivers. It has been observed that the messages help drivers take appropriate decisions and then better manage the time they spend travelling and deal better with congestion. In order to understand why the content of the messages leads to the behaviour in question we have developed a hypothetical architecture for the mental process demanded by the messages. This paper presents the cognitive model we have developed, which is based on knowledge networks.     

Réflexions sur l'usage des modèles dans les études de transport et les sciences sociales

The mathematical modelling of human behaviours is extremely common in both theoretical and applied transport studies. This paper begins with an attempt to demonstrate the limits which apply to the reconstruction of a human reality (in this case an origin-destination matrix) by means of a straightforward and commonly used model, the gravity model. These limits stem from the fact that economic, social and political factors and historical aspects are ignored. The reasons for the prevalence of models in transport studies are then discussed as are the consequences of this prevalence: perpetuation of a view of the operation of society which is far from being without political implications, the surrender of the political community to experts, pseudo-scientific justifications for projects for which politicians do not wish to take responsibility.     

La surestimation de la distance intervéhiculaire dans le brouillard

The difficulties of driving in fog are usually perceived in terms of lower sight distances and reduced ability to anticipate. However, the fall in the quality of visual information can also lead to errors in judgement by affecting the way drivers perceive their environment and their movement within it. We have conducted a series of experiments in a fog chamber and on a driving simulator, with the main aim of investigating the influence of fog on vehicle headway perception. Our results have revealed that distances are seriously overestimated in fog, and that this is likely to contribute to lower headways under such conditions, In fog an overestimation of headway between 20 and 55% was observed when vehicles were visible only as a result of their rear lights, which is the case in night-time or thick daytime fog. Under these conditions, the characteristics of vehicle lights become extremely important. Overestimation of distance becomes greater when vehicles have only one rear light instead of two, and when their two reac lights are close together. Perception of vehicle distance is therefore improved by two rear lights, placed as far apart as possible to indicate the dimensions of the vehicle. No significant overestimation of headways was found during thin or moderate daytime fog, when the vehicle outline remained visible. The results have shown the importance of the familiar size of vehicles as an indicator of distance in the situations we have investigated. They confirm the hypothesis that basic mechanisms of space perception are modified in fog.     

Les objectifs de qualité urbaine et de sécurité routière dans la planification de la mobilit'e plan urbain de trafic (Brescia) et plan de déplacements urbains (Aix-en-Provence), deux visions différentes

Apart from the fact that it is of interest in itself to conduct the first comparison between Urban Travel Plans in France and Italy, this paper has the more general aim of examining a number of ideas which are shared by the scientific community, namely that urban policies and planning practices take ittle account of, or even completely ignore, road safety, the relationship between town planning and transport planning and consultation.     

Âge des conducteurs de voiture et accidents de la route: Quel risque pour les seniors ?

Increasing life expectancy and the fact that the baby boomer generation is reaching retirement age are increasing the size of the elderly population. As road users, seniors have quite specific travel behaviours, and this has an impact on accidents. This paper adopts a quantitative approach with a view to showing the specific characteristics of elderly drivers as regards travel, accidents and road risk. Towards this end it surveys a number of previous studies and takes advantage of recent data to update some of the findings of these contain. Some road risk indicators are described, and attention is paid to the methodological bias inherent in the methods employed. Our analysis shows that the presence of seniors on the roads is growing as the proportion, particularly of the women, in this group who are accustomed to driving increases. They nevertheless cover fewer kilometres than other drivers and develop compensatory strategies, for example not driving when conditions are difficult or driving more slowly than other drivers. When they have accidents they tend to be more severe because of their greater vulnerability. They have higher crash involvement at intersections as a result of detection and estimation difficulties in the driving task. The excess crash risk per kilometre driven for seniors that was observed a few years ago is tending to fall, or even disappear, if the low mileage bias is taken into account.