Update Reports on Speed Limits in Iowa

The National Highway System Designation Act of 1995 repealed the national maximum speed limit (NMSL) and returned authority to set speed limits to the states.

Task Force

When the national maximum speed limit was repealed, the Iowa Safety Management System Coordinating Committee formed a Speed Limit Task Force to provide information to legislative decision-makers on the subject of speed limits. That task force has issued reports on the subject of speed limits in 1996, 1997, 1998, 1999, 2000, and 2001.

Higher Iowa Speed Limits Authorized in 1996

Iowa law was amended in 1996 to authorize the Iowa Department of Transportation (DOT) to increase speed limits to 65 mph on certain divided multi-lane highways.

Engineering Studies Preceded Iowa Changes

Before any changes were made in Iowa, the Iowa DOT undertook an engineering review of highways eligible for increased speed limits under the new law. A total of 355 miles of rural, four-lane divided expressways were included in the review. As of January 2001, the speed limits were increased to 65 mph on more than 631 miles of Iowa freeways and expressways.

Update Reports

The 2001 report included here is a compilation of data gathered in Iowa and other states regarding the effects of changing speed limits on travel speeds, crashes, injuries and fatalities. Older reports are also available.

• Update Report on Speed Limits in Iowa - 2002 (.PDF) (1.362M)
  • Compact Version (.PDF) (597K)
  • HTML Version
• Summary of Speed and Crash Data and Key Findings on Iowa's Rural Interstate System (2002) (.PDF) (97K)
  • HTML Version (2002)
• Updates to 2002 Speed Limit Report Appendix: Tables 1-9 (1970-2000 Summaries) (October 15, 2002)
  • Table A-1: Statewide
  • Table A-2: Rural Interstate
  • Table A-3: Rural Primary
  • Table A-4: Rural Secondary (County Roads)
  • Table A-5: Rural Totals
  • Table A-6: Municipal Interstate
  • Table A-7: Municipal Primary
  • Table A-8: City Streets
  • Table A-9: Municipal Totals
• Update Report on Speed Limits in Iowa - 2001 (.PDF) (268K)
• Update Report on Speed Limits in Iowa - 2000 (.PDF) (270K)
• Update Report on Speed Limits in Iowa - 1999 (.PDF) (233K)
• Update Report on Speed Limits in Iowa - 1998 (.PDF) (453K)

For Further Information

Tim Crouch
State Traffic Engineer
Highway Division, Engineering Bureau,
Office of Traffic and Safety
Iowa Department of Transportation
800 Lincoln Way
Ames, IA 50010
Telephone: (515) 239-1513
E-Mail: [email protected]

The draft of the plan is available on this site in Adobe Acrobat^TM (PDF) format.

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last modified on: by Michael D. Pawlovich