Tuesday, April 22, 2014

Princeton Cycle Facilities Part 2: Shared Lane Markings

This post is part of a series reviewing the effectiveness of bicycle facilities in Princeton. In this post, we discuss 'shared lane markings', also known as 'sharrows'. The previous entry in this series, about regular roads, can be read here.

Princeton was an innovator in the local region when it rolled out a program of 'shared lane markings' on its streets in 2011 (see example from Nassau Street in photo above). The 'sharrows' were a recommendation of the Princeton Joint Pedestrian and Bicycle Advisory Committee, which developed a policy paper on cycle facilities in 2010. (You can read the original documents at our online file archive.) 

Sharrows are intended to achieve several objectives. First, they are an additional reminder to cars that cyclists may be present and have the right to cycle in the road. Second, they suggest a safe position on the road for cyclists (cyclists are supposed to cycle right through the middle of the white thermoplastic arrow). In many cases, this position is much further out into the road than drivers or novice cyclists might assume. A mid-lane position is often safer, as it is easier for cars to see cyclists, and it also moves cyclists out of the 'door zone' where they might be struck by people exiting parked vehicles. As such, sharrows are a useful contribution to Princeton's support for cyclists. Sharrows were also recommended because they don't require extra street space, don't require significant investment to install, and are approved by the MUTCD.

On the other hand, sharrows do not provide any dedicated space for cyclists, and they are based on the idea that cyclists will be comfortable riding in mixed traffic. As discussed in yesterday's post about cycling on regular roads, some cyclists are happy in mixed traffic, riding in-between cars...but many others find it a terrifying prospect! In other communities, sharrows have been found to have a very limited effect in encouraging more people to take up cycling. In one study, 45% of cyclists rode on the sidewalk even when sharrows were present in the adjacent traffic lane.

The 'NACTO Urban Bikeway Design Guide', which is the most up-to-date, federally-endorsed guidebook for bicycle facilities in the USA, recommends very specific instances where sharrows are appropriate. Notably, the Design Guide recommends sharrows as part of a  'bicycle boulevard' concept. Berkeley, CA has an inter-connected network of bike boulevards, which are designated streets with low traffic speed and volumes, which are laid out to make it safe and stress-free to cycle between different parts of the town. Princeton Pedestrian and Bicycle Advisory Committee has been pursuing the boulevard concept, as part of the evolving Princeton Bicycle Masterplan.

On the other hand, the NACTO Design Guide specifically states that "Shared lane markings should not be considered a substitute for bike lanes, cycle tracks, or other separation treatments where these types of facilities are otherwise warranted or space permits." Bicycle boulevards, where sharrows are most helpful, are only appropriate where real vehicle average speed is a maximum of 25 mph, and where traffic volume is less than an absolute maximum of 3,000 vehicles per day. In Princeton, we have sharrows on many streets which do not match these criteria, including the example of Nassau Street, seen in the picture above. Going forward, we would aim to use sharrows where they are most appropriate, and not as a substitute for cycle facilities that are more appropriate for enabling safe and stress-free cycling.

As mentioned above, it would be really great to hear back from people about the type of cycle facilities that you would most like to see in Princeton. Do you like sharrows? Let us know!

1 comment:

  1. Princeton was an "innovator" by introducing sharrows? How about a bit of dedicated infrastructure innovation? They are a start, but all they do is make cyclists and drivers (perhaps?) feel that cyclists presence is legitimate.