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.     

Comportements,personnalité, conduite des véhicules automobiles

This study was carried out on a population of 127 offending drivers of both sexes. A validation study was also performed on a sample of 51 offending drivers of both sexes. On the basis of a questionnaire that dealt with road related parameters (violations accidents, vehicle power) and use of the Guilford Zimmermann Temperament. Survey (with the Parenti driving questionnaire in the validation study), a variety of analyses were conducted which demonstrated essentially that offending drivers do not posses a specific psycholonical profile, (unlike motorcycle and HGV licence holders who do). However, it emerged that men and women have a different relationship with the car which is an object of narcissistic investment for men, contributing to their image and self-esteem and becoming a means or supporting and asserting their masculine identity) and that the intensification of male identity is associated with a variety of behaviours that increase the risk of both violations and accidents. Furthermore, while violations in themselves are not predictive of risk, perhaps revealing more about the nature of surveillance activities, frequent reoffending can lead to the assumption that the individuals are potentially dangerous drivers.     

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.     

Modèles linéaires généralisés appliqués à l'étude des nombres d'accidents sur des sites routiers: Le modèle de Poisson et ses extensions

Models that link accident frequencies at road sites with traffic volumes and road characteristics provide reference values which are of value when carrying out diagnostic studies and deciding on preventive measures. Such models can be developed using generalized linear modelling techniques, which are able to take account of the Poisson properties of accident frequencies at road sites. The Poisson models obtained for road sites are frequently everdispersed, so extended forms of the Poisson model (quasi-Poisson, negative binomial a high percentage of the studied sites, in which case zero-inflated models also have to be considered. This paper presents an overview of these methods which are illustrated by modelling the relationship between accident frequency site characteristics and traffic volume on a large sample of bends.     

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.     

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.     

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     

Certification des automatismes numériques dans les transports guidés : projets européens CASCADE et ACRuDA

This paper presents current work which deals with the certification of automatic train protection systems according to European standards and has three main sections. The first deals with the current situation as regards third party conformity certification on the basis of a reference document. The role of notified assessors and the requirements of European standards such as Cenelec 50126, 128 and 129 are discussed and the essential elements of the European high speed train interoperability directive are given. The second section summarizes the results of the Cascade project (Certification and Assessment of Safety-Critical Application Development) which is part of the Esprit III programme. This project deals with the harmonization of the various evaluation and certification approaches for safety critical software in railway applications. Its aim is to formulate a shared evaluation method to enable safety critical software to be certified by any notified assessor in a State in the European Union with the same criteria and rules, and in accordance with applicable European standards. The third section of the paper presents the Acruda project (Assessment and Certification Rules for Digital Architectures) which supplements the work on software carried out in Cascade. This project concerns the certification of hardware architectures and makes it possible to implement certification rules for the computers used to ensure the safety of train control systems.     

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.     

Évaluation des potentiels de réduction des trafics automobiles dans le cas de la zone dense francilienne

The Pari 21 research project does not attempt to justify a move towards a radically different system—practically everything there is to say about the benefits and disadvantages of cars in cities has already been said. Instead, the project will perform simulations and assess, from the point of view of individuals, the feasibility of a transport system that is based mainly On the use of modes Other than the private car in the densely populated zone Of the Greater Paris Area (Paris city plus the inner suburbs). By constructing and evaluating transport policy scenarios, this research also aims to measure the potential for reducing car use in highly urbanized zones, particularly that which results from the reduction in journey speeds which are a likely consequence of the policies in question The method is based on repeated iterations of a simulation model which combines the assignment of round trips to modes other than the automobile with reformulations of transport supply. Demand is channelled towards personal modes (walking, cycling), public transport and a combination of personal and public modes. These iterations are based on the 1991-1992 Paris Region comprehensive travel survey which recorded all the round trips by car made in a typical day by the individuals living in the zone (i.e. the sequence of all trips made between each time the individual leaves home and returns home).     

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.