The impact of hourly measured speed on accident risk in the Netherlands: results from an exploratory study using GIS

Abstract

Several scholars have defined the urgent need for more research to identify the precise relationship between speed and crash involvement more fully. In this paper, we present the first results of an exploratory study carried out in the Brabant Southeast police region in the Netherlands. Hourly speed measurement data over a period of two years were collected from loop detectors on the municipal and provincial road network and were related to crashes. Different aspects of traffic intensity, speed and their impact on crashes were studied, including absolute speed, speed variation and the proportion of excessive speeders, both for vehicles under and over 5.2 meters long. The study also discusses a number of methodological aspects associated with this kind of analysis. The results show that although absolute speed plays a more important role on roads where speed limits are low, it is the variation in speed that correlates more with crashes when speed limits are higher. Given the limited study area, the results of this work cannot be generalized without risk. However, they offer interesting insights that deserve further investigation in a nationwide cross-sectional study.