Designing for Target Speed

The American Association of State Highway and Transportation Officials (AASHTO) defines design speed as “a selected speed used to determine the various geometric features of the roadway. The assumed design speed should be a logical one with respect to the topography, anticipated operating speed, the adjacent land use, and the functional classification of the highway.” The working definition for “target speed” is the operating speed that the designer intends for drivers to use. The topic of “design speed” versus “target speed” typically focuses on low-speed urban and suburban roadways, especially where the 85th percentile speed is higher than the posted speed limit. Research is needed to gain a better understanding of how roadway, roadside, and non-roadway elements influence the operating speed—the actual speed of the driver—in order to improve roadway designs and reliably achieve desired speed outcomes. The objectives of this research are to (1) determine the effects of roadway, roadside, and non-roadway elements on operating speeds on roadways with a target speed between 30 and 40 mph and (2) develop recommendations on how the findings can be incorporated into the roadway design process.


  • English


  • Status: Inactive
  • Funding: $750000
  • Contract Numbers:

    Project 15-76

  • Sponsor Organizations:

    National Cooperative Highway Research Program

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

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Crichton-Sumners, Camille

  • Performing Organizations:

    Texas A&M Transportation Institute (TTI)

    400 Harvey Mitchell Parkway South
    Suite 300
    College Station, TX  United States  77845-4375
  • Principal Investigators:

    Brewer, Marcus

  • Start Date: 20200729
  • Expected Completion Date: 20231229
  • Actual Completion Date: 20231229

Subject/Index Terms

Filing Info

  • Accession Number: 01707636
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 15-76
  • Files: TRB, RIP
  • Created Date: Jun 6 2019 7:49PM