This study was commissioned by the New South Wales Road Safety Bureau and the Federal Office of Road Safety to examine the causes of crashes involving heavy vehicles in New South Wales, Australia in 1988 and 1989 and to suggest countermeasures. The study included a retrospective examination of 83 fatal crashes involving heavy vehicles on two New South Wales highways, an analysis of mass data on heavy vehicle crashes in the State from 1982 to 1988, and an analysis of traffic, freight movement and environmental factors.