An Evaluation of the Safe Speed Limit Setting Procedure and Tool for Utah

Details

• Creators:
  Schultz, Grant G. ; Ward, Cory K ; Andersen, Shannon
• Corporate Creators:
  Brigham Young University. Department of Civil and Construction Engineering
• Corporate Contributors:
  Utah. Department of Transportation. Research and Innovation Division ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  50th Percentile 85th Percentile Speed Procedures Speed Limits Speed Limit Setting Procedure Speed Limit Setting Tool Traffic Speed Measurement
• Publication/ Report Number:
  UT- 22.17
• Resource Type:
  Tech Report
• Geographical Coverage:
  Utah ; United States
• Edition:
  Final Report May 2021 to August 2022
• Corporate Publisher:
  Utah. Dept. of Transportation. Research Division
• Abstract:
  The purpose of the research project is to evaluate the Speed Limit Setting Procedure (SLS-Procedure) found in National Cooperative Highway Research Program (NCHRP) Project 17-76 for implementation on Utah roadways with the goal of aiding the agency in overall road safety surrounding speed limits. The Speed Limit Setting Tool (SLS-Tool) automates the SLS-Procedure and displays the process in a transparent way. The Procedure and Tool emphasize the importance of context by classifying roadway segments into one of four Speed Limit Setting Groups (SLSGs). The research team analyzed 29 locations that were divided into 66 uniform segments that could be individually analyzed with the SLS-Tool. Then, the suggested speed limits that resulted from the SLS-Tool were compared to the recommendations presented in the UDOT speed studies. Using the SLS-Tool, the closest 85th percentile speed was only suggested in 18 percent of segments, rounded-down 85th percentile speed was suggested for 21 percent of segments, and the closest 50th percentile was used in 54 percent of the segment suggestions. When compared to the UDOT speed study, 62 percent of the segments shared the same result as the SLS-Tool suggestion, 23 percent were a lower suggestion, and 15 percent were a higher suggestion. A high crash rate and the lack of bike lanes on urban streets were the most common reasons for a closest 50th percentile speed suggestion. The research team recommends that UDOT use the SLS-Procedure and SLS-Tool as a reference when performing future speed studies. The use of these resources can aid an analyst in complying with the Utah guidelines on when to depart from a traditional 85th percentile speed.
• Format:
  PDF
• Funding:
  21-9058
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:839be1dda19afb82c9219a78b3d966db4c26b733494814ad8af141dd846905b2
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/64463/dot_64463_DS1.pdf
• File Type:
  [PDF - 1.87 MB ]