Analysis of Effectiveness of Social Factors and Traffic on Distribution of Headway Case Study: Tehran-Qom (Persian Gulf) Freeway

Headway distribution of vehicles in the traffic stream is considered as a crucial
factor. In this study some statistical models are fitted on measured time headway.
Traffic data were gathered from Tehran-Qom freeway in two different months, in
April as a high traffic flow and in January as a low traffic flow. In this study simple and
combined models were fitted on field measured data. The goodness of fitness were
evaluated after calibrating the statistical models parameters. Results showed that the
distribution of headways can be predicted by proposed statistical models.