Citation

Madsen TKO, Lahrmann H. Transp. Res. F Traffic Psychol. Behav. 2017; 46: 438-450.

Copyright

(Copyright © 2017, Elsevier Publishing)

DOI

10.1016/j.trf.2016.05.008

PMID

unavailable

Abstract

The purpose of this study is to compare the safety of cyclists in five bicycle facility layouts in signalized intersections at various traffic volumes in order to assess if some layouts are better than others with regards to cyclist safety and to develop methods to facilitate this comparison. The five layouts included two full-length bicycle tracks with and without separate right-turning lane, two truncated bicycle tracks - one in which cyclists and right-turning vehicles merge in the right-turning lane, one continued into a narrow bicycle lane - and a recessed bicycle track. Using two different definitions of traffic conflicts the safety of cyclists in each layout is calculated as the risk of a cyclist being involved in a conflict with left- and right-turning vehicles at low, medium and high vehicle volumes, respectively. In total, around 35,500 left-turning vehicles, 38,000 right-turning vehicles and 16,000 cyclists going straight ahead were observed, resulting in 12 left-hook and 25 right-hook traffic conflicts for the reaction-based indicator and 25 left-hook and 80 right-hook traffic conflicts for the time-based indicator. The results show that regardless of which of the two conflict indicators were used, the number of conflicts was too small to make firm conclusions about which layout is safest for cyclists at various traffic volumes, although the study was based on 80 h of video recordings from each of the five intersections. However, a recessed bicycle track seems to be safer than the other geometric layouts. In order to facilitate the detection of conflicts, we developed watchdog video analysis software to reduce the amount of video. This software compressed 400 h of video into 64 h, i.e. 16% of its original length. The use of this software is particularly important to provide enough conflicts for an analysis if even larger traffic conflict studies should be carried out.