NCPA - National Center for Policy Analysis


April 1, 2005

Urban planners in Denver, as well as other major cities, are implementing a controversial measure designed to slow traffic and reduce accidents: converting one-way streets into two-way streets.

The plan runs counter to the consensus of traffic engineers and experience, says transportation engineer Michael Cunneen and economist Randal O'Toole. In fact, two-way streets increase traffic congestion, increase accidents and make pedestrians less safe.

  • In Denver, two one-way streets have already been converted: Grant and Logan, which used to carry about 7,000 cars per day now carry only 600 and 11,600 cars per day, angering nearby residents.
  • In Lubbock several one-way streets were converted to two-way in 1996; as a result, traffic on those streets dropped by 12 percent, but accidents increased by 25 percent.
  • In 1993, Indianapolis converted a major one-way thoroughfare into a two-way street; accidents increased by 33 percent.
  • Moreover, pedestrians have to worry about crossing lanes of traffic coming in opposite directions, adding to their risk as well.

On the other hand, converting two-way streets to one-way streets reduces congestion and decreases accidents:

  • One study indicates that traffic speeds increase on one-way streets by 37 percent, but with a 38-percent decrease in accidents.
  • In several Oregon cities, converting two-way streets to one-way streets led to 23 percent more traffic but 10 percent fewer accidents, meaning the accident rate per million vehicle miles declined by 27 percent.

Despite overwhelming evidence against converting one-way streets, city officials in Austin, Tampa, Seattle and other cities are considering such plans, which cost millions of dollars to implement.

Source: Michael Cunneen and Randal O'Toole, "No Two Ways About It: One-Way Streets Are Better Than Two-Way," Center for the American Dream, Issue paper2-2005, February 2005.


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