Simply put, this study adds to the growing evidence that traffic congestion has been made worse, not alleviated as road builders claim, by more and bigger highways. Instead it would be smarter to plan our communities better so that we aren't forced to drive everywhere, and to provide greater transportation choices such as commuter light rail and expanded bus service. This may be evidence for a strong sprawl inducing impact of large increases in lane mile capacity relative to the existing infrastructure. Recognition of these impacts implies that the benefits of new highway construction are less than would be calculated from a static analysis that included no induced travel impacts. One study in Oregon showed that by planning development so that people have easy access to commuter trains and other public transportation choice, traffic for new development can be reduced from 10 car trips per day to 6 trips per day.
More roads lead to more traffic like bigger pants tend to lead to more weight gain.
We need to change our philosophy to reduce, not increase sprawl and traffic. The Sierra Club is calling on state and local leaders to spend at least half of their transportation money on safety improvements to existing streets and roads, and for public transportation alternatives, and promote traffic impact analysis on new sprawl development, and good planning measures to minimize traffic.