NCPA - National Center for Policy Analysis

Dispelling Myths About Speed Limits

May 25, 1999

Many people assume that low speed limits minimize traffic hazards and that speed limits are established with motorist safety as the primary concern. Actually, speed limits are often a compromise between scientifically established speed management practices and political-financial interests, says James Baxter, president of the National Motorist Association.

  • If speed limits are properly set -- at the speed of the 85th to 90th percentile of drivers -- the vast majority will comply.
  • However, most speed limits are set 10 to 15 m.p.h. lower than what is appropriate -- in order to discourage traffic or urban sprawl, or to optimize safety for pedestrians, for example.
  • And no consistent correlation between speed enforcement and traffic safety improvement has been shown; for example, fatality rates on the German Autobahn, which has minimal speed enforcement, are virtually identical to the U.S. Interstate system, on which millions of speeding tickets are issued.
  • In fact, high profile traffic enforcement campaigns costing hundreds of millions of federal gas tax dollars oftentimes result in increased numbers of traffic accidents.

While faster speeds do increase crash severity, historical studies show higher crash rates for substantially slower traffic. And Interstate highways are designed to accommodate very high speeds with very low crash rates.

Source: James J. Baxter (National Motorists Association), "The Mythology of Setting Low Speed Limits," Consumers' Research, April 1999.


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