W. Rauh's ground breaking study compared the risk of bicycle lanes that were designated only by a painted line on the street as opposed to those which were segregated by a curb. The presence of the curb more than tripled the risk of collisions at intersections for either passing through (3.4x instead of 1x) or for making a turn into or across traffic (11.0x instead of 3.4x).
The primary reason for the increased risk evidently results from the quick transition from relative confidence in the invulnerability of drivers and bicyclists separated by a barrier to one where they have merged into the same vulnerable space. As the number of intersections and drive ways increase in frequency, the higher the risk.
There are also some hidden risks when there are two separate one way traffic bike lanes on both sides of a roadway (planned for Jerusalem, instead of the usual single lane for supporting two way traffic for bicycles). In the case of the two separate bike lanes the risk increases exponentially when bicycles emerge from the lanes in order to merge or turn across traffic.
The fact that there are lanes on both sides of the street, bicycles turning across traffic from both sides of the street increase the risk even more than the risk factor calculated in Rauh's study.
Wolfgang Rauh, in Velo Secur ("Issues of Bicycling Safety"). International conference from 2-5 May 1990 in Salzburg. Conference proceedings published by ARGUS (Working group for Environmentally-friendly Urban Traffic), Vienna, 1991.
No comments:
Post a Comment