Analysis of Bunching in Rural Two-Lane Traffic

A model is proposed for the formation of bunches in rural two-lane traffic. An overtaking rate is defined and estimated from data. The relation between these overtaking rates and various other factors is investigated. It is shown that with the data available, the model provides an exceptionally good fit. Formulas are then derived for the rate of delay to vehicles on rural roads caused by restricted overtaking. The model is not recommended for the analysis of urban traffic. For urban traffic, it is suggested that variance/mean ratios provide a useful measure of bunching.