Recent research from the Curtin University Sustainability Policy Institute in Perth, Australia, confirms that urbanites around the world are using their cars less. This "peak car use" phenomenon is occurring in at least eight major countries. (In the United States, that trend was noticed a few years ago by the Brookings Institution.) In Europe, cities where automobile use actually declined from 1995 include London, Stockholm, Vienna, and Zurich. In the United States, they include Atlanta, Houston, Los Angeles, and San Francisco.
Scientifically, no one knows exactly why car use is diminishing, but the Curtin University researchers cite a few theories, including growth of public transportation and high gas prices. The most interesting hypothesis comes from Thomas Marchetti, the researcher who noticed that human beings appear to hit a psychological wall when it takes more than an hour to get to work. Thus, when cities become more than "one hour wide," they stop growing or they become dysfunctional, or both. No matter what the reason, it would appear that the public is rational enough to recognize that they can only use their cars so much. If a reasonable commuting alternative arises, they are likely to use that instead.
If the public is rational about its travel, can the public policy follow their lead? The Curtin University researchers say traffic engineers will have to shift their thinking away from roads that accommodate cars to "road diets," "traffic calming," and other transportation modes. The Infrastructurist posits that public officials should actually fund those activities.
How rational is the public in choosing its commuting devices? Can city planners capitalize on the one-hour commute limit to maximize traffic mobility? Is the "peak car use phenomenon" so unique to developed urban areas that the solutions are fundamentally different than for other places? Are there lessons from big cities on car use that could extend to less densely populated regions?