Effects of Bicycle Boxes on Bicyclist and Motorist Behavior at Intersections in Austin, Texas

Abstract

Provision of bicycle facilities at intersections is often inadequate and can lead to unsafe interactions between motorists and bicyclists. The bicycle box is a tool intended to improve the predictability of bicyclist stopping position at an intersection by allowing bicyclists utilizing a bicycle lane to position themselves in front of motorists during a red phase. The bicycle box in this application is meant to reduce the possibility of a right-hook collision, where a right-turning motorist collides with a through-moving bicyclist departing the intersection. The primary goal of this study was to determine what effect, if any, bicycle boxes have on bicyclist and motorist behavior. In 2009, 950 bicyclists were observed at two sites in three phases: existing conditions, after bicycle box markings were installed, and after a green colored pavement marking was added to the bicycle box and approaching bicycle lane. The predictability of bicyclists’ behavior improved based on the increased percentage of bicyclists who used the bicycle lane to approach the intersection, departed the intersection before motorists, and stopped in front of the motor vehicle queue. While only 20–26% of bicyclists stopped in the bicycle box area after installation of the bicycle box markings, over 90% of bicyclists stopped in front of motorists and were therefore more visible to motorists. The addition of the green pavement markings led to significant improvements in bicyclist behavior, but at a considerably higher material cost. Motorist encroachment on the bicycle box was common at both sites as well as illegal right turns on red at one site. No bicycle-motorist collisions were observed during any stage of the study.