Headways, rear-end collisions and traffic: The case of French motorways
ARON ; BIECHELER-FRETEL ; HAKKERT ; PEYTAVIN
Type de document
COMMUNICATION AVEC ACTES INTERNATIONAL (ACTI)
Langue
anglais
Auteur
ARON ; BIECHELER-FRETEL ; HAKKERT ; PEYTAVIN
Résumé / Abstract
This presentation reports the main results of a recent study on French motorways which aimed at contributing to the improvement of the knowledge on headways and on rear-end collisions. From this study we can state the following: at very low flows the rate of accidents is important, and the percentage of short headways is not small. At high flows is seems that the rate of accidents and the percentage of short headways is important. Neither rain nor visibility have any influence on the headways and correlatively the rate of accidents is important. Truck drivers are implied in a number of collisions, their headways are not longer than those of car drivers. The short headways are more frequent on the fast lane. Some periods must be processed separately in order not to confuse the effect of the drowsiness and the effect of traffic. The percentage of short headways varies linearly from 11 % at very low traffic level to 45 % (for more than 1000 vehicles/hour/lane) and to 62 % for heavier traffic (1100-1200 vehicles/hour/lane). The percentage of very short headways (less than 1 second) varies also with the traffic level, but the effect of the flow is smaller (the slope is divided by two). Very short headways are more behavioural than due to the traffic constraints.
