The Diminishing Returns of Highway Building

Today on the Streetsblog Network, David Levinson at the Transportationist presents some interesting explanations about why so much American road building is a poor use of funds:

In this image, the black lines represent roads and the blue dotted line represents a traveler. At some point, adding additional roads is subject to diminishing returns, saving people less time per dollar invested. Image: David Levinson

We are not building much new transportation in the US not just because the costs are too high, but because the benefits are too low.