How do drivers choose a travel speed? Implications for speed management strategies in Australia

Abstract

Speeding remains a major contributor to trauma on our roads, held to be a major factor in around one-third of fatal crashes and over 10 percent of all crashes (Bowie & Walz, 1994; Fildes & Lee, 1993). This study reviewed speed management strategies and key factors that should be considered through a comprehensive review of the literature. One of the most frequently used methods of managing travel speeds is the posted speed limit. The primary purpose of the speed limit is to advise drivers of the maximum reasonable and safe operating speed under favourable conditions, therefore considered to be a road safety measure. Further, speed limits are designed to be (i) related to crash risk, (ii) provide a reasonable basis for enforcement, (iii) fair in the context of traffic law, and (iv) accepted as reasonable by most road users. Traditional approaches to setting speed limits (e.g. engineering approach using the 85th percentile speed) are compared with an alternative view to setting speed limits: the Safe System approach. This approach requires that all aspects of the system work together for the safest possible outcome, with speed representing a critical component. The findings suggest that there are some inherent issues in traditional speed limit setting guidelines, particularly as drivers lack awareness of the true relationship between speed and road trauma, under-estimate crash and injury risk and over-estimate what is a safe speed, and that there is often a mismatch between environmental cues and speed limits. There are opportunities to review and strengthen speed management policies and practices with a view to creating environments that promote safe behaviour rather than relying on drivers/riders to decide what is a safe speed, complemented by strengthened Police enforcement and increased community knowledge and awareness of the importance of speed to road trauma.