Safety and operational analysis of 4-lane to 3-lane conversions (road diets) in Michigan.

Details

• Creators:
  Lyles, Richard W. ; Siddiqui, M. Abrar ; Taylor, William C ; Malik, Bilal Z. ; Siviy, Gregory ; Haan, Tyler
• Corporate Creators:
  Michigan State University. Department of Civil and Environmental Engineering
• Corporate Contributors:
  Michigan. Dept. of Transportation. Office of Research & Best Practice
• Subject/TRT Terms:
  • Lane distribution
  • Traffic lanes
  • Four lane highways
  • Three lane highways
  • Highway safety
  • Lane distribution
  • Traffic lanes
  • Four lane highways
  • Three lane highways
  • Highway safety
• Publication/ Report Number:
  RC-1555
• Resource Type:
  Tech Report
• Geographical Coverage:
  Michigan
• Edition:
  Final report.
• Corporate Publisher:
  Michigan. Department of Transportation
• Abstract:
  Road diets, specifically 4-to-3 lane conversions, implemented in various locations in Michigan were studied to determine the safety- and delay-related impacts, develop crash modification factors (CMFs), and develop guidelines that would be useful in deciding when it might be desirable to implement such road diets. The results of the operational analysis support a guideline that suggests that 4-to-3 lane conversions result in significant delay when average daily traffic (ADT) exceeds 10,000 and, more importantly, when peak hour volumes exceed 1,000. A CMF of 0.91 (after adjustment for background citywide trends) for all crash types is recommended although the factor is not statistically different from 1.0. There was considerable site-to-site variation among the 24 sites studied, and this should always be considered when a road diet is contemplated. A study-by-study literature review and suggestions for implementation strategies are also included.
• Format:
  PDF
• Funding:
  2010-0294
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/23856/dot_23856_DS1.pdf
• File Type:
  [PDF - 755.98 KB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:1695c3c7ad0cf985c58690397f2d71c105013f53dcea83f7f8e01860a4e0412e700ab9c78bf91bd5b54881ba2a6c599ee56691f61d23705d5eaa8afca8d6792a