Shared Paths With Two Lanes or Three
Lester Earnest (les at cs.stanford.edu)
Two-way paths to be shared between cyclists and pedestrians are often needed in urban areas. This note examines two alternative ways of doing that.
Two Lane Paths. The traditional lane configuration is to paint a center line in the path and expect cyclists and pedestrians going in each direction to stay to their right. That generally works reasonably well as long as the traffic density is low but problems arise when there are high volumes. Pedestrians generally move slower than bikes but are more maneuverable, so if a pedestrian takes a side step just as a cyclist is passing there may be a collision.
Three Lane Paths. An alternative configuration is to divide the path into three lanes. For example. With a path 12 feet wide there could be three lanes, each 4 feet wide, with the center lane given to pedestrians and the two outer lanes to cyclists. Pedestrians going in opposite directions will be able to see each other and maneuver to avoid collisions while cyclists should not encounter head-on traffic.
Pedestrians overtaking other pedestrians might need to negotiate with those ahead or can wait until there is no traffic in a bike lane on either side and go around. Bikes can generally pass each other in a four foot lane but if one of them is a trike (which is what I have been riding since a solo crash in 2004 left me partly made out of titanium) then it may be necessary for the overtaking rider to wait for an opening in the pedestrian lane to go around.
There should be lane markings at path entry points to indicate who should be using each lane.
Conclusion. To my knowledge the three lane configuration is not in use anywhere but I expect it will work better than the two lane layout.