But even subtle growth can have a dramatic impact. The environmental activist group Friends of the Earth estimates that just 10 miles of a new four-lane highway create the equivalent lifetime emissions of nearly 47,000 Hummers, and the public health implications are equally alarming. By overfeeding development, highways are fattening up America and Americans at the same time. A Georgia Tech study shows that every hour spent in a car each day increases the likelihood of obesity by 6 percent, while walkable, mixed-use neighborhoods decrease it by 7 percent, lowering the overall relative risk of obesity by 35 percent. The National Institutes of Health links obesity to decreased life expectancy, so more highways mean more sprawl, more fat, and shorter lives. Our roads are literally killing us.

Freeway expansion is intended to relieve congestion, but in fact it encourages more commuting and longer distances, so cities are trapped in a vicious cycle, enabling overdevelopment. The insidious sprawl of my hometown, Houston, was one of the reasons I left; it seemed impossible to do anything without a car, and “pedestrian” was a pejorative term. So imagine my shock when the city began reclaiming its inner-city neighborhoods and installed a light-rail transit system. If Houston can do it, any place can.

Wait – an infrastructure and political climate that encourages people to spread all over hell and spend 15% of their waking hours driving back and forth in a car has _consequences_? Consequences that extend beyond the personal preferences of a single person? What?

From here.