Characteristics of rollover crashes

Abstract

Rollover crashes are investigated to identify ways in which active and passive safety solutions might be applied most effectively. Results of at-scene investigations of rural crashes by a research team and police reports of all crashes are reviewed. 236 crashes to which an ambulance was called, including 64 rollover cases, were investigated in the at-scene study, conducted on rural roads in South Australia. During a similar period police reports were compiled on 163,578 crashes, including 2,653 rollover cases. Injuries were sustained in 50% of the rollover cases but in only 18% of all other reported crashes (crashes resulting in a casualty or property damage of more than $1,000 were required to be reported). About half of the single vehicle rollover crashes in both studies occurred on straight roads; in the at-scene study after the vehicle drifted onto the unsealed shoulder. In almost every such case the vehicle yawed out of control before rolling. This is illustrated by photographs of the yaw marks and the final position of the vehicles, together with scale plans of these vehicle motions. The percentage of crashes which resulted in rollover increased with the posted speed limit: 5% at 80 km/h to 31% at 110 km/h. Vehicle factors relevant to crash and injury causation are also addressed. Combining information from these two studies overcomes to some extent their individual imitations, of small sample size in one instance and less detailed data in the other. These studies illustrate, among other matters, the type and frequency of situations in which stability control can be expected to prevent rollover crashes in a region where the roads are rarely wet, together with the importance of limiting travelling speed.