A Speed Awareness System to Improve Heavy Vehicle Safety

Heavy vehicle rollovers on horizontal curves are not only serious safety hazards, but also the source of substantial costs to heavy vehicle operators, other road users and managers of the road network. The primary cause of such rollovers is excessive speed for the curve geometry, and the usual ameliorative measure is provision of advisory speed signs on the approach to the curve. In cases where signage does not sufficiently reduce the occurrence of rollovers, consideration may be given to installation of a speed awareness system, designed to monitor the characteristics and operation of heavy vehicles approaching the curve and to provide a warning to each vehicle deemed to be in potential danger of rolling over. This paper describes the development of a specification for such a system for a particular location. It explores the influences of vehicle type, load height, load mass and speed on vehicle stability, through the use of dynamic computer simulation. From the results of this investigation, the system characteristics were specified in terms of which vehicle and operational characteristics should be measured, where those measurements should be taken, what decision rules should determine the need for a warning and how that warning should be delivered.