Classifying Passing Maneuvers

Abstract

Passing an impeding vehicle on a two-way two-lane roadway is a complex maneuver because of the variety of passing conditions and driver behavior. In this study, the supposition that passing maneuvers can be classified on the basis of a quantitative description of passing behavior was examined by analyzing data collected during a passing experiment conducted in a driving simulator. Evidence was found to support the following hypotheses: (a) the speed increase of the passing vehicle during the passing maneuver is smaller when the speed difference between the passing and impeding vehicles at the moment of initial acceleration is greater and (b) the speed reduction of the passing vehicle during the latter portion of the passing maneuver is greater when the time to collision with the oncoming vehicle at the moment when the passing vehicle returns to the right lane is greater. Therefore, it was concluded that the start of a pass can be classified by acceleration behavior, and the end of the pass can be classified by deceleration behavior. This behavioral approach is an improvement to classifying passing maneuvers on the basis of a qualitative assessment of the passing conditions, as in establishing the AASHTO passing sight distance design criteria and the minimum passing sight distances in the Manual on Uniform Traffic Control Devices for Streets and Highways. A particular passing behavior, described by a specific acceleration and deceleration behavior, could be used to modify or update these criteria, thereby improving the guidance given to passing drivers and potentially the safety of passing areas.