Wanting to know more about sharrows, I went to Wikipedia and read about shared lane marking. (I had to read about a district in Sheffield, England first.) I was a little unclear on the topic, I suppose, as I had thought that sharrows were rather vague in their application. Nothing could be further from the truth, as there appears to be a small if well defined body of traffic standards that apply to shared lane markings.
If you've (like me) not been paying close attention to the sharrows issue, here's a brief definition: Sharrows are "bicycle use" road markings that are installed where complete bike lanes cannot be installed for various reasons including:
- Not enough cyclists to justify bike lanes;
- Too expensive to install bike lanes;
- Use of bike lanes would require loss of parking; and/or
- Use of bike lanes would require road widening;
- Improve positioning of both cyclists and motorists on streets without bike lanes;
- Reduce aggressive motorist behavior;
- Prevent wrong-way bicycling;
- Prevent bicycling on sidewalks;
So, what happened? Well, the city of San Francisco (CSF) videotaped and analyzed a lot of traffic behavior. In 6 street locations, and before painting the streets, they taped cyclists' positions on the street, motorists' locations, and clearances afforded cyclists by motorists. (They did this for 1100 cyclists.) Then they painted the sharrows with the center of the figure 11'-0" out from the curb. And they ran the video study again. The results of the study are as summarized in the graphic at right.
I don't know about you, but I think these are pretty significant results. Cyclists are clearly less crowded towards parked cars, and motorists are clearly making better affordances for them.
One of the interesting things that the CSF found was that while the "chevron" design eliminated wrong-way cycling where it was used, the "bike-in-house" design appeared to have no effect in this area. For this reason (and the slightly better affordances noted above), the CSF approved the "chevron" design for use on CSF streets.
Because the markings were applied to the streets with no preceding public education program (the CSF evidently felt this might have skewed the results,) cyclists and motorists were then surveyed as to their perception and understanding of the markings. I won't go into the results of this survey in detail, (you can peruse the PDF if you like, as it's all there,) but will hit on some highlights:
- Most cyclists felt that the markings indicated a bike route;
- 60% of the cyclists felt an increased sense of safety;
- 33% of the cyclists felt that the markings caused them to "take the lane" more;
- 35% of the cyclists felt that the markings improved motorists' behavior;