Ashkan Sharafsaleh

Bicyclist Intersection Crossing Times

In support of efforts to improve traffic signal timing to accommodate bicyclists’ needs, observations were made of the timing of bicyclists’ intersection crossing maneuvers. Video recordings were made of bicyclists’ crossings and the video images were processed to extract the bicyclists’ trajectories. These trajectories were synchronized with video images of the traffic signals so that the timing of the bicyclists’ maneuvers could be determined relative to the signal phases. The processed data yielded cumulative distributions of the crossing speeds of bicyclists who did not have to stop at the intersection and the start-up times and final crossing speeds of the bicyclists who had to cross from a standing start. A unique feature of these data is the timing information relative to the traffic signal, which is used to define recommended signal times to permit most bicyclists to cross wide arterial intersections safely.

Intersection crossing times of bicyclists

The timing of traffic signals is rarely determined by the needs of bicyclists, in part because quantitative data about the timing of intersection crossing maneuvers by bicyclists have not generally been available. This study built on a video image–processing method developed and reported in a previous study to collect data at five new intersections with diverse physical characteristics and bicycling populations. The video data were processed to produce cumulative distributions of the most important descriptors of crossing behavior of bicyclists: the speeds of bicyclists who did not stop at the intersection and the start-up times and final crossing speeds of bicyclists who crossed from a standing start. The timing information relative to the traffic signal was used to recommend signal times to permit most bicyclists to cross intersections safely. The recommendations took into account differences in the bicyclist population and the physical characteristics of the intersection (such as approach grades).