From "Letters to the Editor" in the Menlo Park Almanac, August 22, 2007. This motorist clearly misunderstood the answer to his question and the problem. There's debris in the bike lane precisely because it's been swept there from the passing cars and trucks.
Bike safety in Portola Valley
I have asked various bike riders for their views on certain safety issues.
Q. Why do many bikers ride directly on the white line of the bike lane rather than within the lane?
A. Debris can be seen and avoided.
Based on the foregoing, one might ask why not put the white line of the bike lane in the middle so debris could readily be seen, and double yellow lines on the outside to delineate the lane, thus encouraging both the bikes and the autos to stay out of each other's lanes.