Guide to the Application of Spatial Segmentation on Travel Time Reliability Measures

Travel time reliability measures create a consistent means of comparing the performance of different highways in the network. Travel time reliability measures inform decisions regarding highway capital and operating investments and facilitate accurate public reporting of highway travel times and performance. Additionally, travel time reliability is a required federal performance measure for state departments of transportation (DOTs) and large metropolitan planning organizations (MPOs). Travel time reliability measures are affected by the way highway corridors are divided into segments for data collection, analysis, and reporting. Corridors with fewer segments may “average out” the impacts of congestion “hot spots” along a corridor, creating less reliability in practice. Shorter and more intentionally defined road segments may have the effect of creating more predictable and consistent reliability measures by isolating the impacts of places that experience more or less episodes of congestion. However, the travel time reliability measures calculated for longer corridors with many “hot spots” can be less certain and comparisons of reliability measures calculated for roads within a network cannot always be trusted. Typically agencies obtain travel time and speed data from third-party probe data suppliers who use predetermined segments. To improve travel time reliability measures, practices, and reporting, transportation practitioners need direction on the application of methods for supplementing these data using segmentation and aggregation to produce the most consistently reliable measures, ones that can be compared across the network and used for public communication and investment decision-making. The objective of this research is to develop a guide for designing, modeling, and applying roadway segmentation in travel time reliability measurement to generate improved reliable predictions across similar roadway contexts.


  • English


  • Status: Active
  • Funding: $200000
  • Contract Numbers:

    Project 08-143

  • 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:

    Weeks, Jennifer

  • Performing Organizations:

    Cambridge Systematics, Incorporated

    150 Cambridge Park Drive, Suite 4000
    Cambridge, MA  United States  02140-2369
  • Principal Investigators:

    Margiotta, Richard

  • Start Date: 20231018
  • Expected Completion Date: 20251017
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01739639
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 08-143
  • Files: TRB, RIP
  • Created Date: May 20 2020 1:13PM