The purpose of this paper is to examine the temporal aspects of driver risk-taking. Car-following is an increasingly common situation, especially on urban motorways, urban freeways and high-volume ring roads around large cities. In this type of road situation the driver's adaptation is crucially dependent on his controlling interaction with other users that could interfere with his driving, and on maintaining "safety margins" that are sufficient to enable him to deal with possible incidents. A specific feature of this margin is the headway he leaves between himself and the preceding vehicle. Several studies have stressed the critical nature of the headways adopted by drivers and the implications of such practices for the overall safety. This type of approach enables the frequency with which such behaviour occurs to be evaluated, and the effect of different variables to be estimated at a global level. On the other hand, it provides little information about the frequency with which a given driver is or is not involved in these critical situations, in what circumstances and for how long. Similarly, the mechanisms by which the driver controls his driving and the regulating actions he carries out cannot be studied in depth. The purpose of out research is to contribute towards the analysis of these aspects and, more specifically, to examine the temporal aspects of driver risk-taking. Our approach represents an in-depth qualitative investigation into driver behaviour in car-following situations. It sets out to define the situational demands to which drivers have to adapt while driving in this road situation as well as to analyse the strategies they adopt to control their safety margins. (A)
Abstract