Factors Influencing Operating Speeds and Safety on Rural and Suburban Roads

The objective of this project was to develop a technical report that describes treatments that result in driver self-selection of appropriate operational speeds on curve and tangent sections. The study was conducted in two phases. The first phase included a review of literature on design features and current practices associated with safer operating speeds and identification of treatments for field evaluations. The second phase involved evaluating treatments to determine their effectiveness in reducing speeds on two-lane horizontal curves in rural and suburban areas. High-friction surface treatment was evaluated at four treatment sites and three control sites in West Virginia. The speed and encroachment analyses found no consistent differences between the before and after time periods. The friction analysis, however, clearly demonstrated that the friction supply increased. Optical speed bars (OSB) were implemented and evaluated at seven sites in Massachusetts, four sites in Arizona, and eight sites in Alabama. Two different designs were tested as part of this research, and the results yielded inconsistent speed reductions at all the test sites. Based on the results, it can be concluded that the OSB designs used in this research were unsuccessful in reducing vehicle speeds. The safety effects of lane-width–shoulder-width combinations on rural two-lane, two-way road segments in Minnesota and Illinois were also estimated as part of this study. Parameters for lane width indicators showed that, with shoulder width ignored, the expected number of total (i.e., all types and severities) crashes increases as lane width decreases, but it is difficult to distinguish the performance of an 11-ft lane width from that of a 12-ft lane width. The main effect of shoulder width was a decrease in the expected number of crashes as shoulder width increased. In addition, the interaction of the lane width indicator and shoulder width showed that shoulder width has the greatest effect on safety when the lane width equals 10 ft. Shoulder width also has a greater effect on safety when the lane width is 11 ft than when the lane width is 12 ft.

• Record URL:
  http://www.fhwa.dot.gov/publications/research/safety/15030/15030.pdf
• 
• Summary URL:
  http://www.fhwa.dot.gov/publications/research/safety/15030/
• Record URL:
  https://rosap.ntl.bts.gov/view/dot/35877
• Corporate Authors:

  KLS Engineering

  45155 Research Place, Suite 200
  Ashburn, VA  United States  20147

  Pennsylvania State University, University Park

  Thomas D. Larson Pennsylvania Transportation Institute
  Research Office Building
  University Park, PA  United States  16802-4710

  University of Utah, Salt Lake City

  201 Presidents Circle
  Salt Lake City, UT  United States  84112

  Federal Highway Administration

  Office of Safety Research and Development
  6300 Georgetown Pike
  McLean, VA  United States  22101-2296
• Authors:
  • Boodlal, Leverson
  • Donnell, Eric T
  • Porter, Richard J
  • Garimella, Dileep
  • Le, Thanh
  • Croshaw, Kevin
  • Himes, Scott
  • Kulis, Philip
  • Wood, Jonathan
• Publication Date: 2015-5

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Final Report
• Features: Appendices; Bibliography; Figures; Photos; References; Tables;
• Pagination: 380p

Subject/Index Terms

• TRT Terms: Evaluation; Friction course; Highway curves; Highway safety; Literature reviews; Operating speed; Road shoulders; Rural highways; Speed control; Traffic lanes; Two lane highways; Width
• Uncontrolled Terms: Optical speed bars
• Geographic Terms: Alabama; Arizona; Illinois; Massachusetts; Minnesota; West Virginia
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors; I82: Accidents and Transport Infrastructure; I85: Safety Devices used in Transport Infrastructure;

Filing Info

• Accession Number: 01567321
• Record Type: Publication
• Report/Paper Numbers: FHWA-HRT-15-030
• Contract Numbers: DFTH61-10-C-00057
• Files: TRIS, ATRI, USDOT
• Created Date: Jun 26 2015 1:41PM