Iowa's Experience with 2-Lane to 3-Lane Conversions

Over the past couple of decades, Iowa has converted several 2-lane urban roadways to 3-lane sections. Most of these have been on low volume roads in smaller communities. However, no evaluation of the effectiveness of these conversions had been attempted. Iowa has recently evaluated the safety impacts of these conversions using a Bayesian approach. Within this paper, initial, tentative results of the analyses are explored, with emphases on the data, results, and possible future applications of these conversions. Relative to total crash history, results are mixed, with some sites indicating a reduction and others indicating an increase in both crash frequency per mile and crash rate.


  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; References; Tables;
  • Pagination: 15p
  • Monograph Title: 3rd Urban Street Symposium: Uptown, Downtown, or Small Town: Designing Urban Streets That Work, June 24-27, 2007, Seattle, Washington

Subject/Index Terms

Filing Info

  • Accession Number: 01091657
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Mar 31 2008 12:12PM