An Empirical Analysis of Vehicle Time Headways on Rural Two-lane Two-way Roads

Study of vehicle time headway distributions is fundamental in many traffic engineering applications, such as capacity and level of service analysis in several contexts (road segments, priority junctions, roundabouts, merging maneuvers, etc.). In recent years, other fields of interest have also been represented by vehicle generation in traffic micro-simulation models and driving simulation applications. This paper presents results from an experimental analysis on vehicle time headway distributions on two-lane two-way roads. Our attention focused on rural roads in Northern Italy, with data from inductive loops and radar sensors. Statistical analysis of these data allowed us to test a set of headway distribution models, highlighting their goodness-of-fit with reference to empirical distributions. The final aim of the analysis was create a picture of relations between traffic conditions and headway distributions for a typical kind of road.