Safety Assessment of Climbing Sections of Highways Influenced by Heavy Traffic

The objective of this paper is to evaluate the influence of large vehicles on safety at highway climbing sections. As a distinctive traffic feature in China, traffic mixture means different types of vehicles running in the same flow and having interactions. Vehicles are categorized into small vehicles, medium vehicles, and large vehicles in this paper. As a result of great difference in vehicle structure, geometry, dynamic performance and applications, large vehicles often block the highway traffic flow, especially at the climbing sections of highway, and thus reduce capacity; increases delay and even impact the safety performance of the facility. This paper selected seven representative traffic flow characteristics to analyze the travel mechanism of large vehicles. Then, a safety assessment index at climbing sections was proposed. The results of a case study showed that among the entire climbing sections under the influence of large vehicles, the safest area is the upstream influenced sections, and the most dangerous part is the starting area of the vertical curve.