Risk Compensation Are We Any Further Ahead in Understanding Drivers Accident Risk

Author(s): J. Hemingway
Calgary 2013

Abstract

Risk Compensation Theory (RCT) has been presented by some researchers using physiological responses to stimuli to assess drivers perceived level of risk and workload. Some have measured the Galvanic Skin Response (GSR) or changes in the conductivity of the skin that occur in drivers travelling over different road sections and driving environments to assess driver response to different driving conditions. These studies examined associations between variables including collision rate per vehicle-mile, average GSR per mile and average speed. This work demonstrated that subjective and objective risk, defined per unit of time, are both independent of variations in road conditions as a result of driving being a self-paced task: drivers can adjust the speed of their vehicle in accordance with perceived or actual conditions. RCT has been debated for many years and is now generally accepted as a basis to determine how drivers adjust speed while driving to compensate for changes in perceived risk. In the almost 50 years since this debate began, many changes to roads and vehicle technologies have taken place. Using current data, this paper re-examines RCT and drivers tendency to compensate risk with changes in speed. The study extends previous work by determining if, from a driver’s perspective, there is an optimal level of risk and how this corresponds to a driver’s speed choice. The study confirms that driving is a self-paced task and finds evidence that there is a speed that minimizes drivers perceived level of risk or workload. The study also identifies characteristics of the GSR distribution and proposes alternative analysis methods for these distributions.