An On-Road Examination of Driver Errors at Intersections

A significant proportion of road trauma occurs at intersections. Understanding driver behavior at intersections therefore has the potential to lead to significant injury reductions. This paper presents a sub-set of the findings from an on-road study investigating the nature of errors made by drivers. Of particular interest in this paper is the number and types of errors made by drivers at intersections. To further understand how the complexity of modern intersections shapes behavior these are compared to the errors made mid-block, and the role of wider systems failures in intersection error causation is investigated. Twenty-five participants drove a pre-determined route, incorporating 25 intersections, in an instrumented vehicle. Two in-vehicle observers recorded the errors made while a range of other data was collected, including driver verbal protocols, forward, cockpit and driver video, driver eye glance behavior and vehicle data (speed, braking, steering wheel angle, lane tracking etc). Participants also completed a post trial cognitive task analysis interview. Participants were found to make 39 different error types, with speeding violations being the most common. Over half of all errors made by drivers occurred at intersections, with a failure to indicate on approach to the intersection, indicating too late and travelling too fast to turn being common errors observed. In-depth analysis of a sub-set of representative error types indicates that driver errors at intersections have various causes, including failures in the wider road system, such as inappropriate or poor roadway design. A range of potential system-wide prevention strategies intersection driving errors are proposed.