"ROADWORTHINESS" OF HEAVY VEHICLES

Increasing attention is being paid to the impacts of heavy freight vehicles on road systems. To some extent, the road damage and safety performance of heavy vehicles are related through the vehicle design, including axle configurations, suspensions and tyre properties. The trend to six-axle articulated vehicles is considered in this paper with respect to pavement wear and the stability of the vehicle. It is concluded that current six-axle vehicles appear to combine the virtues of relatively low pavement damage and relatively good stability. Concern is expressed about the dynamic aggressivity of current drive axle suspensions and about the load- sharing ability of current triaxle suspensions. A possible trend to wide single tyres will emphasize these pavement impacts. It is suggested that more stringent requirements for load sharing and dynamic performance in axle group suspensions at maximum weight may be needed, together with parallel controls on roll stability. It is noted that technological advances desired by operators are not necessarily incompatible with the objectives of reducing pavement and safety impacts (a). This paper was presented in Session 4--Vehicle-Road-Vehicle Impacts. (TRRL)