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Status Report, Vol. 47, No. 8 | October 25, 2012 Subscribe

Freeway speeds rise as more drivers exceed posted limits

Drivers continue to exceed posted speed limits on all kinds of roads, but the problem has worsened on freeways and expressways. That is the takeaway from a new national survey of traffic speeds by the National Highway Traffic Safety Administration (NHTSA).

The agency measured free-flow travel speeds during 2007 and 2009 for all types of motor vehicles on freeways, arterials and collector roads across the United States. On limited-access highways, the percentage of vehicles exceeding posted speed limits by any amount jumped 23 percentage points from 2007 to 2009. Fourteen percent of all vehicles traveling limited-access highways exceeded posted speed limits by 10 mph or more during 2007. The percentage rose to 20 percent during 2009. On other types of roads, proportions of drivers exceeding the speed limits fell slightly in 2009 compared with 2007. Still, 13 percent of vehicles on major arterials and 15 percent on minor arterials traveled at least 10 mph over posted speed limits during 2009.

NHTSA cautions that the increase in travel speeds may be due to differences in data collection periods. Continued speed-enforcement campaigns in some states and a 2009 decline in vehicle miles traveled amid the U.S. recession may have had an effect, the agency says. Less-congested roads may have prompted motorists to drive faster.

The survey marks the first time NHTSA has collected nationally representative estimates of travel speeds on public roads for all types of motor vehicles. States used to submit speed data to the Federal Highway Administration, but that requirement was abolished with the 1995 repeal of the national maximum speed limit.

Percentage of vehicles exceeding
speed limit by mph over limit and year

  Percentage of vehicles
Road class 2007 2009 change
Limited access
By any amount 48% 72% 23%
By > 5 mph 28%
46% 17%
By > 10 mph 14% 20% 6%
Major arterial
By any amount 60% 56% -4%
By > 5 mph 34% 31% -3%
By > 10 mph 15% 13% -2%
Minor arterial/collector
By any amount 61% 59% -2%
By > 5 mph 35% 33% -2%
By > 10 mph 16% 15% -1%

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