Impact of Spatial Segmentation on Travel Time Reliability Performance 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. At the minimum, the research shall: (1) Identify different segmentation and aggregation methods for measuring travel time reliability in use by state DOTs, MPOs, and probe vehicle data providers across the nation. (2) Evaluate the variability in travel time reliability measures using different segmentation or aggregation methods appropriate for application in different roadway networks and contexts, taking into consideration roadway type, local density and environment, and temporal and geographic contexts, as appropriate.

Language

  • English

Project

  • Status: Proposed
  • Funding: $150000
  • 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

  • Start Date: 20220504
  • Expected Completion Date: 0
  • 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 18 2020 3:05PM