L’exploitation des données de cartes à puce à des fins de planification des transports collectifs urbains

Smart card fare collection systems are widely used nowadays in urban public transport networks. These systems are bound to facilitate the collection and management of revenues in transit authorities. However, since smart card systems collect a large amount of data on a daily basis, they can be exploited to better characterize the demand and supply of public transport in subways, tramways and bus networks, while data at an individual level should remain strictly confidential. The spatial and temporal dimensions of the data make it very interesting for planning purposes, but the data must first be validated and completed before further analysis. This article presents the results of five years of research conducted in collaboration with theSociété de transport de l??Outaouais, in Quebec. The following analyses are presented: error processing, estimation of alighting points, diffusion of operational statistics, analysis of user behaviour, analysis of network performance, comparison with household survey data and user loyalty modelling.     

Analyse des pratiques d'accompagnement des enfants et de leurs conséquences

It is more and more common to escort children, and adolescents in rural areas, to school, to see friends, to leisure activities, to the doctor's etc. Some elderly persons are also systematically escorted to activities. These escorting trips are mainly by car, with the mother (or the daughter) driving. Whether children are escorted or not varies according to their age, but the practice has becoming increasingly prevalent in Europe since the 1970s. In England children are allowed to travel unescorted average two and a half years later in 1990 than was the case in 1970 and in the same period the percentage of trips which are escorted has increased by a factor of three and a half. Road safety problems and general insecurity in the area where they live lead parents to escort their children. Most trips of this type are by car. The same situation applies in the former East Germany where many households have only recently acquired a car and where traffic is perceived as dangerous. Although this type of organization of daily family life provides short term opportunities, it nevertheless has long term negative impacts on the acquisition of travel independence by children and adolescents.     

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.     

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.     

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.     

Une caractérisation de l'émission acoustique des véhicules au cours des déplacements

Traffic noise is usually measured at fixed points whereas in reality vehicles move and generate noise throughout their trip. This paper therefore puts forward a new method of identifying noise emissions which takes account of the trip as a whole. We have made use of the concept of standard kinematic sequences (which are the elements which form all car trips) and have introduced a new acoustic index to characterize the noise emissions of a vehicle during a sequence. We have achieved this by adapting conventional highway acoustic indices to the way sequences are defined and used. We have calculated examples of these indices from acoustic recordings of isolated vehicles on a test track and from standard sequences.     

Demande de transport de personnes: une théorie unifiée de l'urbain à l'intercontinental Seconde partie: population de l'ensemble des voyages réalisés

This paper proposes a theory which links some of the characteristics of trips made by individuals to the travel price and time provided by transport supply, with reference to the socio-economic context. This model appears to be able to reproduce the phenomena that are observed when there is a change in the supply or context on a given origin-destination link. However, above all, the same model can also reproduce those phenomena (changes in urban development aside) which are different in an urban and an interurban context: greater personal mobility, shorter period away from home, lower value of time among travellers, different modal split for trips, slower increase in the number of trips as a result of the socio-economic context, etc. The first part of the paper shows how each of an individual's potential journeys may be characterized by wishes concerning different aspects of the journey and how the different alternatives for the journey in a given context of transport and accommodation supply can be assessed with reference to the gap between wishes and real characteristics. The second part shows how it is possible to determine the total population of journeys made, with reference to both the context and supply. The theory has been illustrated by numerical results obtained for a variety of situations which are representative of urban and interurban areas.     

Vieillissement et gravité des atteintes lésionnelles des victimes d’accident de la circulation routière

This study uses the road traffic accident casualty register for the Rhône Département to investigate how the risk of severe or fatal injury varies according to age and to describe the injuries that explain the severity. Two groups of road users are investigated, car occupants and pedestrians. A NISS score of nine or over is taken to indicate a severe injury. Data analysis reveals that, for both groups, the risk of severe or fatal injury increases with age. The nature and location of the injuries depend on the age and sex of the victims. With regard to severe injuries, elderly female pedestrians are susceptible to fractures of the femur (and the femoral neck) and all parts of the upper limbs. Elderly male pedestrians are mainly exposed to fractures of the femoral neck. The greater vulnerability of severely injured elderly drivers results in thoracic injuries, which are partly explained by seat–belt wearing. The main cause of death, for pedestrians of all ages and young drivers is severe head injuries. Car occupants over the age of fifty more frequently suffer from severe thoracic injuries. These findings should not, however, be allowed to conceal the differences observed in the general population for the two severity criteria we have analyzed (severe injury or death). Mortality (in relation to the general population) is highest for young car occupants, while lethality (the fatality rate amongst those injured) is highest among the elderly. For pedestrians, both mortality and lethality increase with age. These findings are also applicable to the risk of severe injury. They justify the continuation of passive safety research in order to develop protection systems that are appropriate for the characteristics of car occupants. Furthermore, they should help to increase everybody’s awareness of the vulnerability of pedestrians and stimulate the introduction of preventive measures, particularly for seniors.     

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.     

Les contraintes temporelles dans le processus d'élaboration des PDU le cas de Marseille

The legal procedure (laure) for developing an urban travel plan (utp) and the procedure laid down in the certu guide place powerful temporal constraints on the development of a utp. This paper uses the example of Marseille to examine the rules for developing a utp and pays particular attention to the manner in which these temporal constraints may cause the actual development of a utp to diverge from the approach recommended by the certu. The utp development process is examined in detail by applying three types of data collection and analysis: an analysis of documents, attendance of utp and workshops as observers, interviews with players involved in urban planning and the utp. In order to meet temporal constraints the planning team must modify the stages of the process, but it must also adapt to the strategies of elected representatives which are defined outside of the utp procedure (the search for funding, development of transport and urban planning policies and objectives, etc.) as well as the resulting projects (those in the process of being prepared or those which are prepared before the utp). The utp can thus become an urban travel plan which essentially aims to achieve between projects which are already running.     

Dépenses de transport des ménages en Afrique subsaharienne méthodes et mesures appliquées au cas de Niamey

The knowledge about the proportion of household budget which Africans spend on urban transport is still poor. We have carried out an analysis of a household travel survey to provide some insight into this topic. This paper begins with a review of the literature that illustrates how much different estimates vary and goes on to discuss the effects of a number of methodological decisions, with regard to be robust, in particular as far as to expenditure is recorded, the type of data collection and the selection of an equivalence scale. With regard to an application in the city of Niamey, the authors explain the hypotheses they have made and describe sensitivity tests when different equivalence scales are applied. Although it would seem that travel surveys could benefit from methodological improvements, the results appear to be robust, in particular as far as selection of an equivalence scale is concerned. Because of high running costs, motor vehicle ownership is extremely restricted. Public transport use is a substitute for personal modes, but it is also expensive and a considerable burden on the budgets of the poorest households. Its use is therefore constrained, which limits the ability of low income groups for become truly integrated within the economic and social life the city     

VirMaLab — atelier virtuel de maintenance: un outil d’aide à la décision pour l’optimisation des politiques de maintenance

This article deals with a generic approach called VirMaLab (virtual maintenance laboratory) for reliabilitybased maintenance modeling for complex systems (with multi-components and multi-states). Based on the probabilistic graphical models formalism (also known as Bayesian networks), this stochastic approach takes into account both the degradation process of the considered system (an original semi-Markovian model is proposed) and maintenance strategies (from diagnosis factors to all kinds of maintenance actions). For complete decision support tools, cost parameters should also be considered (maintenance actions, unavailability of the system, running, etc.). In this article, two applications of this approach to rail maintenance are introduced. The first one focuses on the optimization of the compromise refurbishment/repairing of central part of the RER A line. The second one focuses on the comparison and evaluation of various maintenance strategies in the modernization of the command control systems of Paris metro lines.     

Simulation des temps de parcours du transport ferroviaire régional du bassin de vie stéphanois dans le cadre du projet Bahn.Ville

The French-German research project Bahn.Ville, dealing with Rail oriented development and intermodality in German and French urban regions, has consisted in identifying the principles and factors of success of an urban development oriented towards rail, and in testing them in the agglomeration of Saint-Étienne. One of the research-actions focussed on identifying and anticipating the potential impacts in terms of urban development of a new transport system, of the tram-train type, on an existing railway line. The effect of the insertion of new stops on the global journey time is one of the criterion of the evaluation of new stops. A simulation method of the journey times is presented in this paper. The interest and the limits of this approach, regarding the rolling stock choice and the insertion of new stops, are emphasized.     

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.