ROAD SURFACE IRREGULARITY AND VEHICLE RIDE. PART 3--RIDING COMFORT IN COACHES AND HEAVY GOODS VEHICLES (BUSES AND TRUCKS)

Ride, represented by the root means square of the vertical acceleration at the seat-person interface, was measured in long-distance buses and trucks (rigid and articulated) and correlated with riding comfort assessments by drivers and passengers. These measurements were compared with those previously obtained for passenger cars. Results show that bus passengers and truck drivers will tolerate higher acceleration levels more readily than will car occupants. Psychological factors, as well as vibration levels, influence the subjective assessment of ride. Evaluation of the highest measured acceleration levels against recommended International Standard ISO/DIS 2631 (human exposure to whole-body vibration) indicated that truck drivers could, in certain cases, suffer from fatigue-decreased proficiency within their present legally permitted periods of continuous driving. Truck ride could be improved by the more widespread use of suspension seats.