One of the most hilarious (or, hilariously illogical) attacks on expanding bicycle infrastructure that I’ve seen repeatedly pop up over the years is the idea that “bicycle infrastructure costs too much.” It only takes a few moments to reflect and put such costs into perspective.
For one, bikes are clearly much smaller and lighter than cars or trucks. So, the space needed to accommodate bicyclists is obviously much smaller, and the repairs needed from deterioration are also smaller. Furthermore, as you attract more people to bicycling, that pulls people out of their cars, reducing the deterioration and eventual repair costs of the car lanes. Naturally, the benefits improve even further when we think about bridges.
Looking at San Francisco, in particular, the San Francisco Bicycle Coalition recently published an article on the cost of a mile of bike lane in San Francisco versus a mile of other forms of transportation.