This study examines the effect of traffic density on the occurrence of collisions caused by driver fatigue. Selected motorways, dual carriageway and single carriageway roads were considered at a range of traffic flows over a 2-year period in the UK. The primary data were collected from police accident report forms, witness statements, police statements and postal questionnaires. Reports from accident investigation units were also included. It was found that 17% of the 1828 accidents causing death or serious injury were sleep-related. The percentage of sleep-related accidents was highest on the M40 motorway and lowest on the A19 single carriageway. 85% of the sleep-related accidents were caused by men and 15% by women. Young male and female drivers were at much higher risk than older drivers. The rate of sleep-related accidents per mile per year was positively correlated with traffic density (as were all accidents). On motorways the relationship between higher traffic density and sleep-related accidents did not hold true, possibly because the additional vehicles created a more interesting driving environment.
Samenvatting