Document Type

Report

Publication Date

12-31-2018

Abstract

This report identifies the effect of passing distance laws on drivers’ behaviors and bicyclist’s safety during an overtaking maneuver. Using an instrumented bicycle and driver survey, the study measured bicycle passing in a naturalistic field experiment using video recording, an ultrasonic distance measuring device, and a LiDAR. In order to evaluate the effect of passing distance laws, the study examined jurisdictions with a three-foot passing law, with a five-foot passing law, and without a passing law. The experiment required a bicyclist to ride the instrumented bicycle in two-lane and three-lane roads to capture the distance between the bicycle and the overtaking motor vehicle. Moreover, a new analysis algorithm is presented to assess the speed and distance transformation of the vehicles approaching and entering the passing zone of the bicycle in micro level transportation systems. The results demonstrated that drivers’ overtaking distances were significantly greater in locations with the five-foot passing law than in other areas. The study also found that roads with paved shoulders, wider travel lanes, and a greater number of lanes were associated with greater passing distances. In contrast, we found that passing distance was shorter on roads with shared lane markings (i.e., sharrows) or higher truck composition. By comparing the surveys conducted in locations with different passing laws, the study illustrates that drivers usually overestimate the distance that they pass bicyclists. These results can be useful to transportation engineers, policymakers, and legislators who intend to provide efficient designs of road infrastructure to better accommodate bicycles.

ID Number

TRCLC 17-05

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