Examining the Time Headway Distributions on Rural Highways Under Different Traffic Flow Conditions

Abstract

The Time Headway (TH) between vehicles is one of the vital microscopic parameters in traffic engineering. It is influenced by the prevailing traffic flow characteristics of the highway segments. An accurate measure of TH is essential to deal effectively with any given traffic system. The selection of the suitable probability distribution function for a specific condition of traffic remained an open question. This research aims to evaluate the best-fitted TH probability distribution function for different traffic flow levels in multilane-divided rural highways under heterogeneous traffic conditions. The traffic-related data was obtained using a state-of-the-art, non-intrusive Infra-Red (IR) traffic detector system. The IR sensor system was used to collect the traffic data like vehicle class, traffic speed, traffic flow, and TH from the Chennai–Nagapattinam National Highways in India. To interpret and distinguish the driver behavior in maintaining different TH distributions at different traffic flow conditions, the Kolmogorov–Smirnov (K–S) test was used. The descriptive statistical results reveal that the mean TH values under different traffic flow conditions differ from each other, implying that the traffic flow conditions influence the TH distributions. Consequently, the research findings show significant variations in the TH following characteristics for the highway segment under various traffic flow conditions. The estimated TH distributions can be used to build the microscopic traffic simulation models.