This post supplements my previous post linking to documents about Davis bicycle facilities. Please bear in mind that Davis was the first community to introduce bike lanes in the USA, and that its bicycle program strongly favors conventional bike lanes, which are separated from the adjacent lane only by a painted stripe. However, I have found that the Davis documents uniformly and strongly recommend against bike lanes behind barriers or parked cars. Not only that, the recent warnings are more definite than the early ones. Some quotes, starting with the most recent and working backwards in time:
Theodore Buehler, Fifty years of bicycle policy in Davis, CA (Master’s thesis, 2007). See pages 50 ff., “Lane location relative to motorized traffic”.
The early experiments included three different types of bike facilities (see examples at the top of this section):
- bike lanes between car lanes and the parking lane (Third St.),
- bike lanes between the parking lane and the curb (Sycamore Lane), and
- bike paths adjacent to the street, between the curb and the sidewalk (Villanova Ave.).
The first bike lanes included all of these types, to test them in real life to see how effective they were. The on-road lanes worked best, the behind-parking lanes were the worst, and the adjacent paths were found to work in certain circumstances. This is an example of the wide level of experimentation that occurred during this period. Had the city tried to do extensive research without construction, it might have settled on an inferior design. And not having tried all three designs, it might not have recognized it as inferior, and the entire experiment could have been declared a failure.
Dale Lott (one of the early advocates for special bicycle facilities in Davis, who also conducted research as to their safety and effectiveness), “How Our Bike Lanes Were Born“, op-ed piece which appeared in the Davis Enterprise in 2003:
We insisted on some experiments that turned out well and some that were flops.
One flop was on the first block of Sycamore north of Fifth where we put bike lanes next to the curb with parking next to the auto travel lane. It looked great on paper, but was a mess on pavement. When cars turned into the University Mall driveway, they crossed the bike lane. Both driver and rider, whose view of each other had been obscured by the parked cars, had an emergency situation.
David Takemoto-Weerts (University of California, Davis Bicycle Coordinator, A Bicycle-Friendly Community, the Davis Model (conference presentation, 1998)
Because Davis pioneered the bike lane and other bicycle facilities in this country, it is not surprising that some “experiments” were less successful than others. One such example was the construction of “protected” bike lanes where motor vehicle and bicycle traffic was separated by a raised “buffer” or curbing. In some cases, the bike lane was established between the parking shoulder and the curb line (i.e. cars were parked on the left of the bike traffic lane). Needless to say, any “benefits” of such facilities were soon found to be outweighed by the many hazards created for their users.
Most such well-intentioned, but ill-fated designs were phased out long ago. However, some facility design decisions made decades ago were not so easy to remedy. The most pervasive example in Davis is the two-way bike path immediately adjacent to a roadway. Particularly problematic are single two-way paths located on only one side of the adjacent road. The problems associated with these designs have been described in any number of publications, and they are well illustrated at several locations in Davis. In spite of this documentation, some residents, city officials, and developers remain quite vocal in advocating such facilities when new construction is being planned and designed. The city and campus have attempted a variety of mitigation strategies to reduce the hazards or inefficiencies associated with these side paths, but many observers believe that continuing to build such facilities is wasteful at best.
…Protected lanes located between the parking shoulder and curb line have most positive separation. However, the parked cars create sight distance problems at driveways and intersections. Inability to cross streets in midblock in this type of treatment results in two-way usege which, in turn, leads to intersection problems described subsequently…
Sidewalk and Independent paths
Sidewalk pathways eliminate midblock bike-motor vehicle friction. However, frictional interference of pedestrians may discourage usage of these facilities as does frequent interruption by cross streets and driveways or meandering of the path. An additional problem is establishment of a visual relationship between motor vehicles on the sidewalk path on approaches to intersections…