Choix modal et valeurs du temps en Île-de-France

This paper estimates values of time in the Paris region by investigating modal choice. It uses survey data from the 1997 Enquête globale de transport and results from simulation using the model developed by the IAURIF (Institut d'aménagement et d'urbanisme de la région Île-de-France). Initially, the authors applied conventional Logit and Probit models to give estimates for groups of users based on age, gender, income and geographic variables relating to the location of their residence and work. In general our values of time are higher than the official figure. Two extensions of the basic models were then tested. First, with a Mixed Logit model, the heterogeneity of users was considered, then ER-logit model was applied to examine income effects. The main finding is the extent to which the income effect modifies values of time estimates. The paper also presents a separate distribution of values of time for car users and public transport users and an assessment of the proportion of their income that users take into account when selecting a transport mode.     

Choix d'itinéraires et péage urbain Le cas du tunnel Prado-Carénage, à Marseille

This paper has a dual aim. Firstly, to identify the principal factors which explain route choice among drivers to Marseille in the context of urban tolling and secondly to assess marginally willingness to pay in order to save time and improve travel conditions. For this purpose we have used of the results of a 1995 stated preference survey of potential users of the Prado-Carénage tunnel in Marseille. Initially the paper describes the changeover values-of-time using a conventional price-time model. The sample has also been broken down into three homogeneous behaviour classes for each of which a Logit model has been calibrated. Analysis of the results has confirmed that there is no single value-of-time there is rather one (or several) distribution curve(s) of maximum willingness to pay. This illustrates the diversity of individual preferences and behaviours and confirms our starting hypothesis, namely that there is not a single value of time but as many values as there are individuals and that each individual has a large number of values depending on the nature of the trip in question.     

Une comparaison internationale des prix du camionnage Afrique,Asie du sud-est,Amérique centrale

In 1996 inrets carried out road haulage pricing surveys in seven countries in three continents, Africa, South-East Asia and Latin America, in order to gain a clear picture of the higher cost of transport in Africa. There is a considerable variation in the unit costs of road haulage within a particular country, indeed this variation is greater than the variation between the average price in different countries. In particular, the tennage which is transported and the distance involved have a major influence on the price per torine x kilometre. In order to quantify the differences in price which exist between different countries it is therefore necessary to define an indicator which takes account of the main factors which determine prices, other than the country. Varied types of satistical analysis, in particular involving modelling have been used to indicate how these parameter affect the tariffs of transport in each country and estimate the average price for each country for a particular distance or tonnage. The selected indicators all agree that over long distances road haulage is significantly more expensive in Africa than in Asia. There are differences between the African countries, Cameroon being the most expensive.     

Climatisation automobile, énergie et environnement

In the first part of the paper the authors use data from measurement campaigns to demonstrate that automobile air conditioning significantly increases fuel consumption and emissions of regulated pollutants. Thus, under urban conditions, the average increase in consumption for both petrol and diesel vehicles is 3.1l/100km. Although the effects as regards pollutants vary from one model of vehicle to another, the increase in urban cycles is always very marked, in particular as regards NOx (+48%) and particulates (+64%) in the case of diesel vehicles. The paper then presents the results of test rig measurements of the mechanical and electrical energy consumption of air conditioning systems under different vehicle operating conditions (cycles) and for different thermal regimes of the air conditioning unit (depending on external temperature, the temperature set for inside the passenger compartment, etc.). The authors then present the results of pollutant emission and fuel consumption calculations for a passenger car with a 1.4 litre petrol engine fitted with a catalytic converter. These calculations were based on instantaneous data collected on the test rig. The conclusion is firstly that research and development is required to restric the power consumption of air conditioning which tends to increase urban pollution in particular during periods when high temperatures increase the likelihood of ozone peaks. The authors also draw the attention of the government to the need to consider air conditioning systems and other accessories in official emission and consumption measurements.     

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.