Friday, April 25, 2014

Princeton Cycle Facilities Part 5: Multi-Use Sidepaths





This post is part of a series reviewing the effectiveness of bicycle facilities in Princeton. In this post, we discuss multi-use sidepaths. The previous entries in this series discussed regular roadssharrowspaved shoulders and on-street bike lanes.

Princeton doesn't have many bike lanes, but we have miles and miles of shared-use sidepaths intended for use by both pedestrians and cyclists (see the blue lines on this map). A sidepath is a path marked for bicycle use adjacent to a road (see photo above, of a sidepath at Mountain Avenue and Glen Drive in Princeton). In Princeton, sidepaths aren't necessarily marked with much signage, and can appear very similar to a regular sidewalk. One difference is that sidepaths are usually smooth, dark-colored asphalt; whereas sidewalks are usually light-colored concrete with regularly-spaced grooves.

Sidepaths mostly separate cyclists from motorized traffic. As such, many people assume that they are safer than on-street cycle facilities. This is not the case. Statistics show that sidewalk / sidepath cycling is significantly more dangerous than riding in the road (whether in a travel lane or dedicated cycle lane). Cross-streets are a big problem for sidepaths. Cyclists are supposed to dismount from their and walk across each crosswalk. This is definitely burdensome, where sidepaths are interrupted by many cross-streets, cyclists become less and less likely to dismount each time. Cycling across an intersection is very risky, however, and in the event of an accident, the cyclist will be found at fault. Sidepaths are therefore far from an optimal facility for safe and stress-free cycling.

Sidepaths suffer from three further disadvantages. The first is the risk of pedestrian-cyclist conflicts. This may not be as big a problem as it first appears. Until cyclist / pedestrian volumes become quite high, cyclists and pedestrians are usually able to self-segregate on sidepaths. In Princeton University, there are no dedicated cycle facilities- all the paths are designated as multi-use, and yet crashes between walkers and cyclists are not a major problem. A second issue is that experienced cyclists are likely to shun sidepaths. There is no way they are going to get off their bike every block; instead they will just cycle in the roadway. This makes the cycle facility appear superfluous, and may undermine public confidence in the investment. The third issue relates to cars exiting driveways. This is the biggest problem. If a car cuts across a sidepath while leaving a driveway, the potential for a serious accident is high. Consider this photo:




We see a car crossing a sidepath, this time on Princeton Pike, near the Battlefield site. Cyclists have to hope that drivers will be attentive and inch out slowly. The potential for serious vehicle-cyclist conflicts is high.

Considering their disadvantages, why are sidepaths so widespread around the former Princeton Township? One reason is the common, mistaken belief that they are a safer cycle facility than on-street bike lanes. A second reason is that placing cyclists onto what is effectively the sidewalk minimizes the amount of space required for the cycle facility. This allows more space to be dedicated to other road uses, notably wider travel lanes and on-street parking. Wide travel lanes and on-street parking bring advantages to some road users, but we have to question whether these advantages are worth the risk of serious injury to cyclists.

In other countries, which prioritize cycling, cyclists have their own, specialized cycle path, which is a proper travel lane, separate from the sidewalk and the roadway, but potentially marked by different-color surface material or by being slightly raised above the level of the roadway. Here is an example from Copenhagen, Denmark. Note how the sidepath is separated from the sidewalk, raised above the road surface with a small curb, and buffered from the car travel lane by on-street parking bays:


Copenhagen also has specialized intersection treatments to give cyclists their own priority phases. We might wish for these platinum-level cycle facilities, but the reality is that space and resource constraints make it unlikely that we will see anything as good as this in Princeton in the near future. In the meantime, we must ask whether it is worthwhile to expand the use of sidepath treatments around Princeton. There are several major bicycle travel routes, where, because of the primacy of on-street parking, we are forced to choose between a sidepath and sharrows. Both treatments have significant detrimental qualities: sidepaths are potentially risky, and sharrows do almost nothing to make people feel safe riding their bikes. What to do?

On balance, it may be pragmatic to use sidepath treatments in certain cases to encourage people to ride their bikes more. We may not recommend them as a first option, but adding a sidepath may also be better than doing nothing. The goal would be to make the sidepath as useful and safe as possible. The sidepaths that we have in the former Township currently are all too narrow. Cyclists can barely squeeze past pedestrians and dog-walkers. We must aim for a compliant 6-ft minimum width for single-direction sidepaths, and 8-ft for bi-directional sidepaths. We must get the details right about what signage best indicates that the sidepath is a designated cycle facility, that cyclists must yield to pedestrians, and dismount at intersections. We must monitor sidepath use, to see if they encourage more cycling, and make changes if they are not properly used. 

What is your opinion: is it worth expanding the use of sidepaths for cyclists in Princeton? Are they ever acceptable, or should we refuse to build more of them? Leave us a message to let us know.


1 comment:

  1. Love the Copenhagen example (see also Amsterdam and many other European cities), these have the benefit of being rideable. If Princeton is going to persist with these multi-use bike paths, which most cyclists ignore and ride on the road anyway, please invest in making them quality cyclable surfaces.

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