Planning and Design of Passing Lanes Using Simulation Model

Abstract

The present paper describes the planning and preliminary design of passing lanes in difficult terrain in Southern California and is based on an investigation of approximately 560 km (350 mi) of two-lane highways in Imperial, San Diego, and Riverside counties. The need for passing opportunities has arisen for several reasons, the most important being the fact that long sections of highways are marked as no passing zones, which leads to extensive delays, driver frustration, and increased accidents. The planning techniques described herein include the use of video-logs to create a computer file documenting existing highway conditions and a two-lane highway simulation model. The TRARR (traffic on rural roads) simulation model was used to determine the impact of proposed passing lanes and turnouts on level of service. The use of the simulation model allowed the evaluation of a range of passing lane alternatives (including length and location) for a wide range of traffic, vehicle, and driver characteristics. In total, 117 new passing lanes and four turnouts were recommended for the 560 km (350 mi) of State routes that were evaluated.