Road Hogs?

Have you ever wondered how much urban land is devoted to streets and parking? While it's difficult to come up with a precise measure–for instance, it's not clear whether a driveway alongside a house should be considered a street, parking, or neither–some people are willing to venture a guess.

In their 1997 book Streets and the Shaping of Towns and Cities, Michael Southworth and Eran Ben-Joseph say, "In the urban United States, the automobile consumes close to half of the land area of cities; in Los Angeles the figure approaches two-thirds." As sources, they cite a 1992 article by Mark Hanson in the Journal of the American Planning Association and a 1988 Worldwatch Institute study by Michael Renner. But where did Hanson and Renner get their data?

Hanson cites Renner, but Renner's source, it turns out, is self-described neo-Luddite Kirkpatrick Sale. In his 1980 book Human Scale, Sale says the car "demands enormous amounts of space, both in the countryside, where it has so far caused 60,000 square miles of land to be paved over, and in the cities, where roughly half of all the land (in Los Angeles 62 percent) is given over to its needs." Sale did not cite his source and has not responded to repeated phone calls asking him to provide it.

Meanwhile, others have been on the trail. Stephen Marshall of University College, London, posted a message on the Internet questioning the figures offered by Southworth and Ben-Joseph and asking for similar information from planning officials and scholars in other cities worldwide. Marshall has summarized the responses (available at socrates.berkeley.edu/~uctc).

Ray Brindle of ARRB Transport Research in Australia "found that in older areas of Melbourne…the figure was approaching one-third–but that was largely because of the generous colonial pre-auto allocation of space to `streets.'" For modern suburbs, Brindle believes the figure may be less than 25 percent, "suggesting paradoxically that urban areas designed for car use in fact devoted less land to roads and streets." Respondents from other major cities report figures ranging from 6.5 percent to 15 percent.

But even these estimates overstate the percentage of land "consumed by automobiles." Because streets existed before cars, the share of land "consumed by automobiles" may only be land that was devoted to streets and parking after the automobile arrived. The share of urban land dedicated to streets may not have increased in the past 100 years, but the share designated for parking certainly has, because the typical car is parked 23 hours a day. Unfortunately, there are no reliable data on the share of urban land set aside for parking.