@PlanetMoney asks about an economics explanation for why pedestrians use the bike lane. From the nature of their tweets and blog post, I am assuming they mean the people walking on the sidewalk who blunder into the bike lane. I have run in bike lanes as recently as yesterday because bike lanes being asphault are almost always softer and easier on the legs, relatively speaking, than concrete sidewalks. I also assume bike lanes have fewer pedestrians to pass while I am running. Consider the irony.
In any event, the real economic force at work is the law (or principle, or whatever) of unintended consequences. Bike lanes, intended to make cyclists more safe, make them less so. Not only from the errant pedestrian but also from the trailing motor vehicle. Car drivers, reasonably enough, assume that if there is a bike lane, cyclists will use it and stay out of the motor vehicle lane. This is not always possible when bike lanes might contain pedestrians or debris. Bike lanes are actually more prone to fill up with debris since there is not a steady stream of cars passing through them to clear said rubbish away. This is even more true in suburban areas with bike lanes. And don’t even get a resident of Martha’s Vineyard started about bikers who go on the road rather than the path.
Bikes belong on the road, as do cars and, in the right context, pedestrians. The lanes need to be a little wider. People need to move a little slower, and everyone needs to understand and follow the rules. I know that the dismal science tries to explain what is rather than what should be, so enough with the platitudes. It is interesting to note, however, that the Wikipedia entry for unintended consequences cites a case of declining ridership in Australia as a perverse consequence of the law requiring bike helmets.