A two-lane road in rolling and hilly topography may not provide sufficient passing zone length between crests of vertical curves. The use of passing lanes can increase the passing opportunities, alleviating safety and operational problems on two-lane highways in a cost-effective manner. The simulation model TWOPAS was calibrated for different traffic and roadway conditions in michigan. The calibrated model was used to study the operational benefits of providing passing lanes on two-lane highways. Two parameters, delay reduction and percentage vehicles in platoon, were selected for three configurations of road profiles. Simulation runs were made for different traffic volumes and truck percentages. The magnitude of the accident reduction potential of passing lanes was obtained. The total delay benefits were calculated by using a unit value of time established by AASHTO.The total benefit per year for different truck percentages and roadway conditions and the cost of construction for a passing lane were plotted against different average daily traffic values. The traffic volumes at which the benefits equal the costs of passing lanes for different traffic and roadway conditions were obtained.
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