Factors Affecting the Variability of Driver Gap-Acceptance Behaviour

Experiments have been conducted which involved repeated measurements or observation of an individual driver's gap-acceptance behaviour in order to identify factors which influence both within-subject and between-subject variability. The experiments included both simulated and real-life situations and subjects ranged from students with relatively little driving experience to police drivers and members of the Institute of Advanced Motorists. Within-subject variance could be explained in part by the speed and type of the on-coming vehicle, although the greater part of the variability in the subject's critical gap remained unexplained. It is suggested that between-subject variance could be attributed to factors such as extroversion, age, annual mileage and type of vehicle normally driven by the subject, although the evidence here is not conclusive.