Vehicle headway distribution in work zones

Abstract

This study investigates work zone vehicle headway distribution by disaggregating the vehicle headways into four types: car-car, car-truck, truck-car and truck-truck. It first confirms that the four types of vehicle headways are significantly different by performing the Kruskal-Wallis and Mann-Whitney tests using work zone headway data from Singapore. The statistical test results further show that four factors - traffic flow rate, percentage of trucks, work intensity and lane position - have a significant impact on each type of vehicle headway in work zones. A useful methodology is thus proposed to determine the best-fitted headway distribution model for each type, which includes two procedures: determining the best distribution pattern for each type using the maximum-likelihood estimation and Kolmogorov-Smirnov test techniques and formulating the distribution model parameters as a function of the aforementioned four factors. © 2013 © 2013 Hong Kong Society for Transportation Studies Limited.