Bicycle advocates in San Francisco want the city to pave bike lanes with colored pavement, but so far the city has resisted the plan, citing a lack of standards.
"If you've ever been so fortunate as to ride a bicycle in the Netherlands or Denmark you know what a difference it can make to have the "bike space" in the roadway called out directly by a different colored pavement. Declaring bicyclists' right of way in such a readily visible manner grants the bicycle a higher legitimacy in an urban streetscape, and is part of the Dutch and Danish formula for successful mode shares for cycling (39% of trips take place by bike in Amsterdam, 36% in Copenhagen; San Francisco sees probably 5% of trips by bike and aspires to 10% by 2010, per our official Bicycle Plan).
Of course, you don't need to travel to Europe to ride your bike on colored lanes. Brooklyn's got some blue bike lanes, as does Portland, Oregon. We hear that even Sunnyvale has some blue bike pavement now, and Petaluma put down some red bike pavement a while ago.
Colored pavement technology is actually pretty pedestrian these days. Generally the pavement coloring is achieved not by plain paint, which tends to be slippery when wet and not too durable, but rather by coloring the paving medium itself, asphalt or composite material. For retro-fitting existing streets, a simple paving slurry, dyed to the appropriate color, is spread out like peanut butter over the roadway, then ground smooth, leaving a thin layer of colored bike lane. As the pavement wears, the color keeps up (bike traffic wears down roadway much more slowly than cars and buses do). Long strips of colored bike lane can be implemented quickly in this way."
Yet efforts to create colored bicycle lanes in San Francisco have not progressed.
"So far nobody in California or Washington DC has written up specs on colored pavement for bike lanes, so SF's traffic engineers are unwilling to use the "device" for fear of legal liability: someone could use the nonstandard bike lanes against the city in a lawsuit. That's right, someone might claim that they didn't know what they were doing when they ran the red light because they were confused by the green bike lane."