Operating conditions of HFVs are quite different from those of light vehicles. Owing to their large dimensions and weights, the safety performance of many HFVs is such that it would not be tolerated in other road vehicles. In 1981, 20 HFVs per 10,000 were involved in fatal accidents against 3 cars per 10,000. The fatality percentage of hfvs involved in accidents is 10 percent while that of cars is 5 percent. Several studies indicate that handling properties on single artics are better than those of double and triple artics. Their greater low speed offtracking may however impair safety of unprotected road users in urban areas. A US case control study indicates that certain vehicle parameters such as number of articulations may affect safety even more than driver parameters. Head-on collision at 50 kph between fully loaded HFV and a car will expose car occupants to the same deceleration as collision with a barrier or another car at 100 kph. Outwards offtracking in artics increases at high speeds. on a triple artic travelling at 90 kph, with lateral friction utilisation at a moderate level for the tractor, the rear wheels are close to skidding and even very light braking might cause severe skidding. For comments on this paper, see C 6534.
Abstract