Auxiliary Lane for Truck Escape Ramp on Expressways in Mountainous Areas

Abstract:

Based on the headway collection and analysis on the expressway of 8 driving lanes where a truck escape ramp(TER) is constructed, a fitting analysis and a chisquare test were conducted. The results show that the headway is an exponential distribution when the traffic flow of the driving lane on the expressway is no more than 500veh/h. Considering the traffic flow on the driving lane, and the operation speed of errant vehicles and critical headway, a vehicle merging model was proposed using the differential method. The critical headway was obtained under various road conditions through analysis of the changing lane behavior of errant vehicles. Then in the condition of 95% confidence interval of errant vehicles merged in the driving lane of the expressway, the required design length of the auxiliary lane was calculated under different road conditions, traffic flow of outside lane on expressway, and the operation speed of errant vehicles.

Key words:road engineering; auxiliary lane; merging model; truck escape ramp; headway; driving behavior