Characteristics of heavy traffic on various French roads


Type de document
Résumé / Abstract
This study deals with the main characteristics of all in-service commercial vehicles weighing at least 2 tonnes, in order to evaluate pollutant emissions of heavy duty traffic. We have carried out the same study on 3 different road types to provide a precise description of the urban, interurban and international heavy traffic types. At each site, recordings lasted a full week, night and day, so that for all 3 sites more than 20,000 vehicles are fully described. Two different methods have been used which lead to the same results : a large number of vehicle characteristics were collected to analyse both traffic and heavy-duty vehicles. One method couples weigh-in-motion with video recording (a camera is pointed at traffic) in a fully automatic station. A micro-computer processes values of truck weight in real time and selects vehicles over a 2 tonne threshold. Video tapes are subsequently analysed to complete files with make, model, horsepower, shape code and possibly nationality and wether they are equipped with a frigorific unit. The other variables are date & hour, weight by axle, axle number, instantaneous speed, length and wheelbases for each selected vehicle. This method has been applied to the urban and interurban cases. The international traffic was studied with a quite different method : taking advantage of the vehicles' stop at the Mont Blanc tunnel toll (France-Italy border), a survey among truck drivers has provided mainly the same variables (except length, axle number, weight by axle and instantaneous speed but with mileage in addition). Proposed statistics are of two kinds : - an analysis of the heavy traffic for each road type : percentage of heavy vehicles in the global traffic, daily levels, week evolution, day/night differences and composition in 4 vehicle types (van, light truck, heavy truck and bus) ; - a comparative study of the variables characterizing these 4 groups of vehicles : weight and horsepower means and distributions, analysis in relation to nationality, to the day of week, to the fact that the vehicle is equipped or not with a frigorific unit with statistical tests on mean comparison. All these variables form an unique database on commercial vehicles running on French roads. This database can provide input data for models of pollutant emissions

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