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.     

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.     

Mixité sociale et choix modal : importance des dimensions symboliques dans l’attrait des transports collectives

Our understanding of transport mode choice is largely based upon functional attributes, such as travel time, cost or accessibility. It is important, however, to also look at symbolic and affective attributes. Indeed, one of the main differences between mass transit and private car use is strongly symbolic: public transport compels users to confront social diversity. Given a hypothetical choice between those modes, 200 residents of the Parisian region were asked five times to evaluate (measuring usage intention on a six point scale: ?3 meaning never and +3 meaning always, with no neutral point) the attractiveness of bus versus car-based transport, according to relative travel time and bus users’ population type. The results show that the symbolic dimension (the social mix) strongly contributes to the desirability of a transport mode, as does the functional dimension (travel time).     

Besoins en information et problèmes d'utilisation des transports ferroviaires par les personnes déficientes visuelles

This paper describes some of the findings of the biovam project, which deals with the difficulties encountered by the visually impaired when travelling on public transport, for example buses, the underground or trains. The biovam project brings together a team of researchers who are specialized in the accessibility of transport to disabled persons, mobility instructors for the visually impaired and two public transport operators, the ratp (the Paris Region Public Transport Authority) and the sncf (French National Railways). The biovam project performed a survey which identified the difficulties encountered by visually impaired travellers, and then conducted an inventory of the technical devices which could alleviate these problems. This paper pays particular attention to train travel, which differs from other modes in particular as regards frequency of use, journey duration and the nature of the infrastructure and the rolling stock. The presented findings have led to a number of recommendations and the organization of an experimental program which has renewed financial support from predit.     

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.     

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.     

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.     

Mobilité et accès à la voiture chez les personnes âgées: Évolutions actuelles et enjeux

In France, and in most other industrialised countries, demographic ageing means that in the next decades there will be a rise among the elderly in vehicle ownership and driving for daily trips, long distance travel and leisure trips. This paper demonstrates the existence of these trends by drawing on a variety of statistical sources — National Transport and Communication Surveys, Urban Household Travel Surveys (Lyon) and surveys on French holiday practices. We nevertheless demonstrate that this structural change exhibits a high degree of differentiation with regard to gender, household income, place of residence and state of health. This change, which increases car use, is expected to continue during the next few years, especially among elderly women. Long term changes in lifestyles encourage the view that in the future people will cease to drive at a more advanced age. The increase in car use has important long-term implications in two areas. On the one hand it will affect road safety, on the other hand it raises the issues of the sustainability of mobility and the obligation to meet the needs of persons who are no longer able to drive.