Minnesota Department of Transportation

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Minnesota Speed Monitoring Program


speed limit signs showing various speed limits

Minnesota Speed Monitoring Program

In 1974, the National Maximum Speed Limit of 55 mph was implemented for all roadways within the United States as a term of the Emergency Highway Energy Conservation Act. This corresponded with lower traveling speeds, as well as a significant decline in traffic fatalities. With these favorable effects, Congress maintained the National Maximum Speed Limit, not only as an energy measure but also as a safety principle.

Within the same year, state enforcement of the 55 mph speed limit law became a prerequisite for receiving federal funding for highway projects. States were required to achieve a 50% compliance rate for the new National Maximum Speed Limit. This means that at least half of the drivers were be compliant with the posted speed limit of 55 mph. If these criteria were not met, sanctions against a state’s highway construction funds would be incurred. In order to evaluate state’s compliance rate, programs that monitor roadway speeds were implemented.

In 1987 the National Maximum Speed Limit was amended with the Surface Transportation and Uniform Relocation Assistance Act of 198, which allowed states to raise the speed limit to 65 mph on rural freeways. The Federal Highway Administration would not require states to monitor the 65 mph roadways until Federal Fiscal Year (FFY)1995.

From 1980-1994, Minnesota roadway speed data were collected at 34 locations. These data collection locations and analyses remained relatively consistent. Speed data were also collected and monitored at additional random short term data collection points on a quarterly or annual basis.

In FFY 1995, the monitoring program was changed drastically. FHWA provided a Lotus program to perform the speed calculations include the 65 mph roadways. Many of the data collection sites also changed in order to include as many automated recording sites as possible.

The National Maximum Speed Limit was repealed with The National Highway System Designation Act of 1995; speed monitoring and submission to the FHWA would be performed on a voluntary basis as determined by each state. Although speed monitoring was not mandatory, MnDOT opted to continue to monitor roadway speeds. The new speed monitoring program has been modified to better fit Minnesota's needs.

In 2005 the posted speed limits were increased on 850 miles of Minnesota roadways in order to bring the posted speed limit closer to actual travel speeds. This increased speed limit also corresponded to a one-year heightened speed enforcement program.