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CTS lunch seminar, November 4, 11.30

Published Oct 13, 2014

“When do drivers yield to cyclists at unsignalized roundabouts?
Empirical evidence and behavioral analysis”

Ary P. Silvano*  Xiaoliang Ma            Haris N. Koutsopoulos

Cycling popularity has shown an increasing trend during the last decades in many cities of Europe and USA because of its environmental and health benefits. However, cyclists are frequently involved in traffic accidents, especially, when they interact with vehicles at unsignalized intersections. Besides, there is still lack of evidence and analysis on how such interaction is performed. This paper explores empirical evidences of the vehicle-bicycle interaction on a typical Swedish roundabout, and provides insights into factors influencing car drivers’ yielding decisions when they interact with cyclists. The vehicle-bicycle interaction was divided into several categories of event groups, and their speed differences were analyzed by group. Furthermore, logistic regression was applied to model behavioral aspects of such interactions. The observed data showed a higher and significant variability among the vehicle groups; whereas, bicycle speeds presented lower variation across the groups. The modelling results revealed that the yielding probability decreased when the speed of the vehicle was higher. On the other hand, the bicycle speed had little impact on drivers’ decision to yield according to the results. More importantly, the results showed that the yielding probability was significantly increased by the proximity of the cyclist to the conflicting zone. The results indicated that the yielding rate of drivers can be improved by keeping vehicles’ speed under 20 km/h, by which drivers have the capacity to detect and yield to cyclists in the facility.

Please confirm your attendance by October 31st. No response is required for decline.

Lunch is served from 11:20.

Christian Savemark
PhD student at CTS

Page responsible:Gunilla Appelgren
Belongs to: Centrum för transportstudier (CTS)
Last changed: Oct 13, 2014