Influence of Safety in Performance Assessment of Two-Lane Highways: A Critical Review

Abstract

Traffic operations on two-lane roads are different from that of multilane roads because of the presence of opposing traffic. More often than not, faster vehicles get impedance from slower ones, entrapped inside platoons and delayed. The delay caused to these vehicles depends on both the flow of traffic and the proportion of slower vehicles in its composition. Drivers’ of delayed vehicles search for an acceptable gap to perform passing operations. At times, a part of drivers becomes reluctant to move in platoons, especially when such delay is long enough, and they start exhibiting risk-taking behaviour while passing impeding slower vehicles. Such attempts significantly affect operations and safety of traffic. The problem is, however, more acute when the prevailing traffic is heterogeneous with a sizable proportion of slower vehicles. The present study, thus, elucidates the need for considering both operation and safety in the performance assessment of two-lane two-way highways under such traffic situations.