Evaluation of 70 mph Speed Limit

Principal Investigator:

Reginald Souleyrette, reg@iastate.edu (other projects)

Co-Principal Investigator:

• Tom Stout, stouttom@iastate.edu (other projects)

Project Status: In Progress

Start Date: 03/01/2006
End Date: 12/31/2006


Research Objective: In July 2005, the Iowa DOT implemented a change in the speed limit for most rural interestate highways in Iowa, from 65 mph to 70 mph. Before the legislation passed that changed the limit, there was considerable discussion of the possible impacts of the changed speed limit. Common expectations were that an increase in the speed limit would result in an increase in the number and severity of crashes on the interstate system. This study will focus on several areas where the speed limit change may have had an impact on travel.

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