Scoping Study: Vertical Visibility Constraints -- Vertical Curvature Traffic Control Devices

Horizontal and vertical curves can obscure key roadway features or activity that may lie ahead of unaware drivers. Roadway curvature is a significant factor in roadway departure crashes, injuries, and fatalities. As land use has developed and activities on roads have changed, the potential for conflicts has grown. It is impractical and beyond the resources of roadway authorities to improve all roadway alignments to attain optimal sight distance. This is a growing concern as active transportation increases in many rural areas, especially those experiencing increased tourism. Horizontal curvature on roadways where drivers’ views are obstructed has been thoroughly researched, leading to well-accepted strategies for traffic control devices in the Manual on Uniform Traffic Control Devices (MUTCD). However, similar research has yet to be conducted for vertical curves. The objective of this research is to develop a scoping study to clearly define and refine the research needs, objectives, and expected products necessary to address vertical visibility constraints, including exploring the relevance of crash data to vertical curves and developing a research work program to explore solutions. The intent of potential larger, follow-on, NCHRP study is to obtain data from vertical-curvature-related crashes to assess the details of occurrence, frequency, and severity, and to better understand road user needs, rather than relying on approaches used in prior studies.

• Record URL:
  • http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=6033
• Supplemental Notes:
  • This project has been tentatively selected and a project statement (request for proposals) is expected to be available. The problem statement will be the starting point for a panel of experts to develop the project statement.

Language

• English

Project

• Status: Proposed
• Funding: $150,000.00
• Contract Numbers:

  03-161

• Sponsor Organizations:

  National Cooperative Highway Research Program

  Transportation Research Board
  500 Fifth Street, NW
  Washington, DC  United States  20001

  American Association of State Highway and Transportation Officials (AASHTO)

  444 North Capitol Street, NW
  Washington, DC  United States  20001

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Project Managers:

  Turner, Anne-Marie

• Start Date: 20261001
• Expected Completion Date: 0
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Crash data; Highway curves; Sight distance; Traffic control devices; Traffic safety; Visibility
• Subject Areas: Data and Information Technology; Highways; Operations and Traffic Management; Safety and Human Factors;

Filing Info

• Accession Number: 01991716
• Record Type: Research project
• Source Agency: Transportation Research Board
• Contract Numbers: 03-161
• Files: TRB, RIP
• Created Date: Jun 2 2026 1:49PM