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Speed Limit Publications

• SPEED LIMIT? - Here's Your Answer (PDF, 437 KB, 2 pp)
• Work Zone Speed Limit Guidelines (PDF, 1.37 MB, 20 pp)
• School Zone Speed Limits (PDF, 152 KB, 1 p)
• Speed Limit Task Force Final Report
  Study on speed limits on local roads (PDF, 2.9 MB, 45 pp)

Speed Management Links

• HEAT
  (Highway Enforcement of Aggressive Traffic) Speed Management Program
• Variable Speed Limits

Quick Links

• 511 - Traffic and Road Conditions
• Minnesota Guidestar
• AAA
• Minnesota Safety Council

Speed Monitoring Station Locations
Map and Speed Monitoring Sites

 

 

 

 

 

 

 

ATR Report

 

 

 

 

 

Speed Monitoring Program

 

Background

In 1974, the National Maximum Speed Limit of 55 mph was implemented for all roadways within the United States as a temporary response to a severe fuel shortage. This prompted not only lower traveling speeds, but also 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 percent compliance rate for the 55 mph speed limit or else incur sanctions against highway construction funds. Programs were implemented to monitor speeds as a measure in determining this compliance rate.

 

In 1987 the National Maximum Speed Limit was amended to allow states to raise the speed limit to 65 mph on rural freeways. This may have been the result of the decrease in compliance scores along with the change in the attitude of the public. The Federal Highway Administration did not require states to monitor the 65 mph roadways until Federal Fiscal Year (F.F.Y.)1995.

 

From the 1980's through F.F.Y. 1994 the speed monitoring program used basically the same sites, categories, and calculations with only few sites being changed because of roadway mileage in each category and switching to some automated sites. A Lotus program developed by Mn/DOT was originally used to calculate the results, but in the final years a Paradox program was used. There were 34 sites, some were monitored every quarter and were considered the base sites, while others were random sites that were monitored only once a year.

 

In F.F.Y. 1995 the monitoring program was changed drastically. A Lotus program sent out by the FHWA was used to perform the calculations. The categories were changed to include the 65 mph roadways. Many of the sites were also changed, incorporating as many automated sites as possible.

 

Late 1995 the National Maximum Speed Limit was repealed and the submittance of speed monitoring data to the FHWA would be performed on a voluntary basis as determined by each state. In order to provide continuity in Minnesota's speed data, it was decided that the monitoring program would continue. Since there are no longer FHWA guidelines to be followed, the program has been modified to best fit Minnesota's needs.

 

The roadway categories have been changed once again, as have the monitoring sites along with their numbering system. In the past, final data was adjusted using a theoretical error correction factor applicable to the federal statistical calculation for compliance scores. This is no longer done. Raw data is preliminarily screened for its validity and final calculations are based upon actual data without any correction factors.