LAUSR

Contraflow is a common traffic strategy used to improve the capacity of outbound roads during mass evacuation. Previous studies have focused on the contraflow network configuration, travel time, and number of evacuated vehicles on a macroscopic level. Only a few researchers have considered microscopic factors, such as the contraflow characteristics and moving bottlenecks caused by coaches and trucks. In this study, the effects of the contraflow strategy were investigated through field experiments and traffic simulations. Traffic data were collected from highway segments where trucks were forbidden under regular and contraflow conditions for analysis of the traffic characteristics and the effects of coach moving bottlenecks. The results demonstrate that the capacity and flow speed of contraflow lanes are lower than normal lanes, owing to the narrow cross sections and unfamiliar driving environment. The moving bottlenecks also reduced the speed of passenger car platoons by approximately 5–20 km/h. Four different contraflow schemes were developed and evaluated by Vissim to examine their effectiveness for minimizing the effect of truck moving bottlenecks. The findings revealed an obvious negative effect of trucks on the performance of the contraflow strategy, indicating the need for specific schemes when the truck ratio is large.