Safety Comparison of Roadway Design Elements on Urban Collectors with Access

The main goal of this study identified by the New Jersey Department of Transportation (NJDOT) can be defined as “the quantification of the effects of management treatments on roadway operations and safety on urban collectors with access.” Since, the urban collector road runs through highly diversified areas, various factors have to be considered when before-and-after comparisons of improvements in terms of safety are conducted in this study. For 25-40 mph urban collectors with access, these are: 1. Increase in lane widths (10 ft or 11 ft to 12 ft); 2. Construction of 4, 6, 8, or 10 ft shoulders; 3. Removal of trees in median and border areas; and 4. Installation of guide rails and vertical & horizontal geometry changes to improve sight distances. Before and after analysis for these countermeasures was conducted via several approaches, including naïve approach, analysis via control groups, analysis via Empirical Bayes approach, and analysis via Full Bayes approach. After conducting before-and-after analysis, Crash Reduction Factors (CRFs) were estimated for each countermeasure. The individual CRF values and their relative order among different countermeasures are similar to the values in the literature. In particular, improvements in vertical and horizontal alignment result in the highest reduction in the accident rate, followed by adding shoulders, median barrier installation, lane width increase, and guide rail installation.

• Record URL:
  • http://www.nj.gov/transportation/business/research/reports/FHWA-NJ-2009-008.pdf
• 
• Summary URL:
  • http://www.nj.gov/transportation/business/research/reports/FHWA-NJ-2009-008-TB.pdf
• Supplemental Notes:
  • This research was sponsored by the U.S. Department of Transportation, University Transportation Centers Program.
• Corporate Authors:

  Center for Advanced Infrastructure and Transportation (CAIT)

  Rutgers University
  100 Brett Road
  Piscataway, New Jersey  United States  08854-8058

  New Jersey Department of Transportation

  Bureau of Research, 1035 Parkway Avenue, P.O. Box 600
  Trenton, NJ  United States  08625-0600

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Ozbay, Kaan
  • Yanmaz-Tuzel, Ozlem
  • Ukkusuri, Satish V
  • Bartin, Bekir
• Publication Date: 2009-4

Language

• English

Media Info

• Media Type: Web
• Edition: Final Report
• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 114p

Subject/Index Terms

• TRT Terms: Arterial highways; Before and after studies; Countermeasures; Crash rates; Geometric design; Guardrails; Highway design; Highway safety; Improvements; Median barriers; Road shoulders; Sight distance
• Uncontrolled Terms: Collector roads; Crash reduction factors; Horizontal alignment; Lane width; Vertical alignment
• Subject Areas: Design; Highways; I20: Design and Planning of Transport Infrastructure;

Filing Info

• Accession Number: 01129897
• Record Type: Publication
• Report/Paper Numbers: FHWA-NJ-2009-008
• Files: UTC, TRIS, USDOT, STATEDOT
• Created Date: Jun 2 2009 2:47PM