Four-Lane to Three-Lane Analysis
Researcher(s)
Principal investigator: Reginald Souleyrette
Other authors: Thomas Stout
Student researcher: Thomas B. Stout
Project status
Completed
Start date: 01/01/05
End date: 06/30/05
Publications
Project web page: http://www.ctre.iastate.edu/research/4laneto3lane.htm
Related publications:
- Three lanes really can be safer than four (Technology News) June 2006
- Four-Lane to Three-Lane Conversions (Tech transfer summary) April 2006
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Sponsor(s)/partner(s)
Sponsor(s):Iowa Department of Transportation
About the research
Abstract: The safety impacts of the conversion of a 4-lane undivided roadway to a 3-lane roadway are evaluated using classical before and after studies, with yoked pairs and the cities of some 14 sites. Iowa DOT databases were used to evaluate the changes in the frequency of crashes, rate of crashes, types of injuries, major causes of crashes, key age groups, single vehicle run-off-road crashes, and direction of travel coupled with initial action. The results indicated that the frequency of crashes was reduced by about 26%, when other changes were accounted for, that serious injuries were reduced, and that older drivers had a reduced risk of crashing