Bicycle facility selection bicycle facility selection : a comparison of approaches.

The genesis of this project came in a context-sensitive design training session for New Jersey DOT. In a discussion on accommodating pedestrians and cyclists on urban streets, the question was asked “how narrow is too narrow?”. The query came from a roadway designer who had been receiving conflicting information from the walking and cycling communities. The pedestrians wanted narrow, slow streets that were easy to cross. The cyclists wanted good cycling infrastructure, which often meant increased width. So where could one find the answer? Direction in the 1996 New Jersey DOT bicycle facilities design guide can be summarised as follows: For speeds of 35 mph and under and: • volumes of 1200 and less - no bike-specific facilities, drivers and cyclists can comfortably share the roadway; • volumes between 1200 and 10,000 - a wide curb lane; • volumes of 10,000 and over - a bike lane. For speeds of 40 mph and over and: • volumes of 1200 and less - a wide curb lane; • volumes of 1200 and over - a bike lane. Yet empirically we know that riding alongside cars travelling at 35 mph is much different than 20 mph. For example Australian guidelines say that no bike-specific facilities are necessary when the speed differential between cyclists and vehicles is 12 mph or less. If the 85th percentile bike speed is 12 mph, then one may mix traffic up to 24 mph. Similarly the Australians provide separate facilities when the speed differential is 25 mph and over, or where traffic travels at 37 mph and above. This brings up the second half of the question: when to separate? At some point the speed/volume characteristics of a roadway are too great for a cyclist to ride comfortably and safely. They need to be separated from the vehicle traffic. This does not necessarily mean a separate off-street shared use path. It may mean a wide bike lane with median-type striping ala New York City. It may mean flexible bollards like those found in Montreal. It may mean a Danish “cycle track” — a bike lane raised half way up the sidewalk curb. It may mean simply an eight-foot wide bike lane, as found in Davis CA. The double sided question: when to mix and when to separate. One way to answer this is to see what various guidelines had to say. (Author/publisher)