How an unexpected incident affects speed related driving performance measures

Abstract

Problem statement While road accidents constitute a major social problem in modern societies, accounting for more than 1.2 million fatalities worldwide and 25.500 in the European Union in 2015 (WHO, 2016), the relationship between speed and accidents is widely recognized in the road safety community and as such, speed is a commonly used dependent variable in transportation human factors research. Speed has been found to be a major contributory factor in around 10% of all accidents and in around 30% of the fatal accidents (TRB, 1998; OECD, 2006). Both excess speed (exceeding the posted speed limit) and inappropriate speed (faster than the prevailing conditions allow) are important accident causation factors (Aarts and Van Schagen, 2006). Furthermore, a number of speed related measures are often used including, average speed, speed variability, 85th percentile speed, maximum speed (Hogema and van der Horst, 1994; Manser and Hancock, 2007). In the last decades, driving simulators have been a very common and useful research tool as they allow the examination of a range of driving performance measures in a controlled, relatively realistic and safe driving