Reversible traffic operations have become an increasingly popular strategy for mitigating the problem of traffic congestion associated with the directionally unbalanced traffic flows that are evident during peak commute periods, planned and special events, construction work periods, and emergency evacuations. Despite the widespread and long-term use of this form of operation, there are relatively few formalized guidelines to direct its planning, design, and operation. To overcome this lack of information, the Transportation Research Board (TRB), through the National Cooperative Highway Research Program (NCHRP) Synthesis Program recently sponsored an effort to identify and evaluate reversible lane designs and practices. Among the findings of this work were the extent to which reversible lane systems and practices vary between locations and the purposes for which it is used. This paper presents a review and comparison of practice in the areas widely regarded to be the most critical locations of reversible roadway segments: the initiation and termination points. This review summarizes the design of these termini points as well as the operational practices that have been employed by road agencies to safely and efficiently transition traffic from one direction to the other. It also highlights particular applications that have incorporated successful and/or innovative practices. The discussions bring to light the important considerations that should be taken into account when planning a reversible lane transition, some of the relative costs and benefits of various design options, and how they may affect the long-term efficiency and safety of reversible facilities.
Abstract