Research on the Safety of the Left Hard Shoulder in a Multi-Lane Highway Based on Safety Performance Function

The left hard shoulder plays an important role in the event of emergency on inside a multi-lane highway, but past studies have not been able to clarify criteria for its installation or quantify safety impact side. In order study influence vehicles traveling highways, based that only studied situation four-lane this paper firstly constructs highway simulation model under different numbers lanes VISSIM traffic and uses Surrogate Safety Assessment Model (SSAM) conflict characteristics lanes. Based above findings, introduces Performance Function (SPF) construct freeway accident prediction model, calibrates by adding indexes affected side basic mode, historical data Badou-Shihu section Guangdong Northern Second Ring Highway as basis differences rates investigated before after setting shoulder. showed average Time Collision (TTC) increased 57.2%, Maximum Deceleration (MaxD) 19.2%, Delta Speed (DeltaS) 15.3% shoulders freeways, conflicts freeways were significantly reduced, was improved considerably. addition, rear-end rate decreased 0.17%, 0.75%, 4.6% one-way three, four, five lanes, respectively, indicating are most effective improving five-lane freeways. results show within reasonable range width (0~4 m), decreases about 1.5% every 0.5 m increase if is considered. Without considering other factors, increasing can reduce number accidents. This indicates significant improvement side, conclusion consistent with results. paper, research, research object extended three-, four-, highways. findings help road authorities develop specifications installing adopt strategies improve level models methods used also build framework future intelligent networked vehicle avoidance systems promote development technologies.