Passing lane optimum length on two-lane highways

Abstract

An investigation into the optimum length of passing lanes on rural two-lane highways is presented in this paper. A passing lane is a short length of added lane to improve passing opportunities on two-lane two-way highways. The study utilized field data and traffic simulation in this investigation, with field data primarily used in calibrating and validating the traffic simulation program. A sensitivity analysis was conducted using traffic level and length of passing lane as the primary variables. The level of association between the reduction in platooning and study variables was examined. Study results showed that, within the range of passing lane length investigated in this study (0.5 mi to 3.0 mi), traffic performance continued to improve with the increase in passing lane length. Moreover, for the same target improvement in performance, the required passing lane length increases with the increase in traffic volume. The passing lane optimum lengths developed in this study all varied in the range between 0.80 and 2.0 miles depending on traffic volume.