The roll-behaviour of trucks around curves

ARRB undertook a study to assess the feasibility of providing the driver of an articulated vehicle with information on the roll-stability of the trailer unit. The study involved the measurement of the roll-behavioural characteristics of articulated vehicles as they approach the roll threshold. Five articulated vehicles were instrumented to measure: (i) the lateral acceleration at the rear of the trailer, (ii) the lateral acceleration and yaw rate in the prime-mover, (iii) the vertical load shift on both sides at the mid-point of the trailer suspension, (iv) the distance and elapsed time from the start of the trip. The vehicle speed, steer path radius and road surface cross-slope were calculated from the recorded data. Results from this study establish that: No single parameter significantly correlated with roll-stability; Sufficient time is available to warn drivers of imminent rollover; Negotiating curves, vehicle/drivers approach vehicle roll-limits at a constant rate; Generally, drivers adjust the vehicle speed and steer path to operate within a narrow band of the vehicle's roll-threshold. A prototype Rollover Warning Device is now being developed.