APPLYING THE LEVEL-OF-SERVICE CONCEPT TO CLIMBING LANES

A summary is presented of one phase of a multiphase study that deals with heavy-vehicle flow on downgrades and is concerned with geometric and flow warrants for the inclusion of truck climbing lanes on two-lane rural highways. One criterion for the introduction of climbing lanes on two-lane rural highways for both upgrade and downgrade directions is based on the level-of-service concept; another criterion is based on speed reduction. A suggested set of volume graphs is devised for the level-of-service criterion, and extensive use is made of a previously developed model for truck equivalency factors. A scheme for the relative location and signing of climbing lanes is also presented. (Authors)