Geometric Safety Design of Freeway off-Ramp-Street Terminal Based on Traffic Flow Characteristic Analysis

Abstract

Off-ramps are the sites of far more crashes and lower capacity than other segments of freeways, thus appropriate design method is of great significance to improve the safety and capacity performance. This paper described a study on the geometric safety design method of freeway off-ramp-street terminal based on traffic flow characteristic analysis. A field survey was conducted in 17 cities in order to investigate the difference of traffic flow characteristics between the terminal and common intersections. Experimental results indicated that continuous traffic flow and high vehicle speed were the most significant features of the terminal. Moreover, several key points of geometric safety design of the terminal were proposed according to the traffic flow characteristics and driving behavior. Finally, a freeway off-ramp-street terminal in Shanxi Province was selected to promote the application of the geometric safety design method. Case study results have shown the promising property of proposed approach to assist transportation professionals in properly designing the terminal.