The Aushiker.com cycling research page has been updated with the addition of a paper looking at the width of two-way separated bicycle paths. The details of the paper follows.
Implications of the Width of Two-Way Separated Bicycle Paths
Garcia, A., Gomez, F. A., Llorca, C. (2015). Effect of width and boundary conditions on meeting maneuvers on two-way separated cycle tracks. Accident Analysis and Prevention, 78, 127-137.
The abstract of the paper follows:
Cycle track design guidelines are rarely based on scientific studies. In the case of off-road two-way cycle tracks, a minimum width must facilitate both passing and meeting maneuvers, being meeting maneuvers the most frequent. This study developed a methodology to observe meeting maneuvers using an instrumented bicycle, equipped with video cameras, a GPS tracker, laser rangefinders and speed sensors. This bicycle collected data on six two-way cycle tracks ranging 1.3–2.15 m width delimitated by different boundary conditions.
The meeting maneuvers between the instrumented bicycle and every oncoming bicycle were characterized by the meeting clearance between the two bicycles, the speed of opposing bicycle and the reaction of the opposing rider: change in trajectory, stop pedaling or braking. The results showed that meeting clearance increased with the cycle track width and decreased if the cycle track had lateral obstacles, especially if they were higher than the bicycle handlebar. The speed of opposing bicycle shown the same tendency, although were more disperse. Opposing cyclists performed more reaction maneuvers on narrower cycle tracks and on cycle tracks with lateral obstacles to the handlebar height.
Conclusions suggested avoiding cycle tracks narrower than 1.6 m, as they present lower meeting clearances, lower bicycle speeds and frequent reaction maneuvers.
I am not convinced this paper adds much to our understanding of the design of bicycle shared paths or bicycle paths and its conclusion to avoid cycling paths less than 1.6 m in width is not that helpful when for example here in Western Australia we are now looking at developing and widening paths to 4 metres. Even if we took the 1.6 metre with as being one lane, we are still looking at a minimum of 3.2 metres, less than what is being proposed.