From the introduction

There is broad consensus that one of the nation’s top priorities should be to rebuild our crumbling infrastructure. The problem is especially dire with the aging public transit infrastructure in the nation’s older, more densely populated cities. The American Society of Civil Engineers (ASCE) gave the U.S. public transit infrastructure a D grade. The Department of Transportation reports that 29 percent of our transit infrastructure assets are in “marginal” or “poor” condition, and the cost of replacing all assets that are past their useful life totals $86 billion.