Speed Limit Studies

Speed Limits

The Effects of Raising and Lowering the Speed Limit
This report, which was prepared for the Federal Highway Administration, examines the effects of raising and lowering posted speed limits on driver behavior for urban and rural nonlimited access highways.

Speed Zoning Synthesis, a USDOT study
This study reviewed the principles and practices used to set speed limits. It is based mainly on a survey of traffic officials conducted by the American Association of State Highway and Transportation Officials (AASHTO).

Did the 65 MPH Speed Limit Save Lives?
In 1987, many states raised the maximum speed limtis from 55 to 65 mph on portions of their rural interstate highways. This press release summarizes the findings of a AAA-funded study conducted by Dr. Charles Lave.

Speed Doesn't Kill: The Repeal of the 55-mph Speed Limit
This study by the Cato Institute shows that, despite dire predictions by "safety" advocates, the repeal of the 55-mph National Maximum Speed Limit didn't result in more deaths.

Did Raising Freeway Speed Limits Affect Traffic Safety?
This study analyzes state-by-state fatality data published by the National Highway Traffic Administration derived from the Fatal Analysis Reporting System and Federal Highway Administration statistics.

Comparison of Speed Zoning Procedures and Their Effectiveness
This report describes the findings of a study conducted to determine if including factors in addition to the 85th percentile speed could increase the effectiveness of Michigan's speed zoning procedure.

New York DOT Study
This press release from the New York Governor's Office highlights the findings of research on raising speed limits in that state. It showed that actual travel speeds stayed the same despite the speed limit increase.

New Jersey Speed Limit Report
This three-year study by the New Jersey Department of Transportation looks at the state's 65-mph speed limit. The analysis supports expanding the 65-mph speed limit.

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The NMA's Position

Speed limits should be based on sound traffic-engineering principles that consider responsible motorists' actual travel speeds. Typically, this should result in speed limits set at the 85th percentile speed of free-flowing traffic (the speed under which 85 percent of traffic is traveling). These limits should be periodically adjusted to reflect changes in actual traffic speeds.