Parking: If You Build it They Will Come… in Their Cars.
This is the second in a three-part series on New York City parking policy.
Part 1: The New York City Parking Boom
In recent years, urban planners have come to accept a somewhat counter-intuitive theory called "induced demand." The theory posits that when you build a new road or widen an existing one to try to ease traffic congestion, the roadway almost always fills to its maximum capacity and traffic congestion grows even worse than it was before. In the mid-1990's British researchers discovered that the opposite of "induced demand" is also true. When roads are narrowed or altogether eliminated, or when it is less convenient or more expensive to drive, traffic doesn't just pile up elsewhere. Rather, traffic disappears.
Traffic jams, it turns out, are the result of tens of thousands of individual human decisions. When it is no longer convenient to drive, especially in a big city with lots of other travel options, a number of commuters will decide to take a different mode of transportation, travel at a different time of day, car-pool, make fewer, more efficient trips, or simply stay at home. The corollary to "induced demand" is often called the theory of "disappearing traffic."
Thanks to the work of UCLA urban planning professor Donald Shoup, city planners now have a significant body of evidence to show that the theories of induced demand and disappearing traffic also apply to parking. In his book, The High Cost of Free Parking, Shoup showed that the more cheap, abundant parking that cities build, the more traffic congestion and automobile dependence cities get.
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