Four-Lane to Three-Lane Conversion

Research projects/reports

• The Effect of Four-Lane to Three-Lane Conversion on the Number of Crashes and Crash Rates in Iowa Roads (3.3 mb *pdf) by Wen Li and Alicia Carriquiry, Iowa State University's Department of Statistics, June 2005.
• Four-Lane to Three-Lane Analysis: Tech transfer summary (138 kb *pdf)
• Guidelines for the Conversion of 4-lane Undivided Roadways to 3-lane 2-way Left-turn Lane Facilities

Papers

• The Conversion of Four-Lane Undivided Urban Roadways to Three Lane Facilities (398 kb *pdf) by Tom Welch, State Transportation Safety Engineer, Iowa Department of Transportation, presented at the TRB/ITE Urban Street Symposium, Dallas, Texas, June 28–30, 1999.
• Converting Four-Lane Undivided Roadways to a Three-Lane Cross Section: Factors to Consider (230 kb *pdf) and abstract (5 kb *pdf) by Keith Knapp, presented at the 69th Annual ITE Meeting, Las Vegas, Nevada, August 1–4, 1999. This paper was prepared for the ITE 1999 Annual Meeting and is published here with permission from ITE.
• Matched Pair Safety Analysis of Four-Lane to Three-Lane Roadway Conversions in Iowa (172 kb *pdf) by Tom Stout, Iowa State University (co-winner of the Midwest Transportation Consortium student paper competition, 2005).
• Urban Four-Lane Undivided to Three-Lane Roadway Conversion Guidelines (460 kb pdf) by Keith Knapp, Woochul Lee, University of Wisconsin-Madison; and Karen Giese, Kittelson and Associates, Inc., presented at the Mid-Continent Transportation Research Symposium, Ames, Iowa, August 21–22, 2003.

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