RES2019-10: Quantify Freeway Safety Service Patrol and Protect the Queue Impact on Transportation Network Reliability

The primary goal of this study is to better understand and quantify the benefits of Tennessee Department of Transportation's (TDOT’s) traffic incident management programs, e.g., HELP and PTQ. The challenge of such an undertaking is in the accurate and fair estimation of the adverse effects of “bad things” that did not happen or were responded to promptly and removed effectively because of HELP and PTQ. Examples of such include secondary crashes avoided, fatalities and injuries prevented, major delay significantly reduced, and emission/fuel consumption minimized. To that end, five phased objectives are identified: (Objective 1) Attain Better Understanding of Incidents/Service Calls and Level of Service. TDOT has good incident data in its Locate/IM and SWIFT. TDOT currently reports the aggregated incident statistics by region on quarterly basis. With the access to WAZE and its crowdsourced incident information and travel time variations, an in-depth spatiotemporal study with much higher granularity would provide new insights in terms of geographical incident distributions, more accurate incident and response times, temporal and spatial clustering of service calls types and incidents, isochronal service information for each region, level of service and response time at different locations, and so on. (Objective 2) Comprehensive Benefits Estimation for HELP Program. Previous studies performed by UTK focused primarily on delay reduction aspects of the HELP program, based on the findings of dozens of prior studies where near 90% of the benefits derive from delay reduction. With new data from WAZE and new models on fuel/emission and secondary crashes, a more thorough benefits estimation for all TDOT regions will be conducted. (Objective 3) Comprehensive Benefits Estimation for PTQ Program. TDOT’s Protect the Queue program is a proactive effort towards better safety and efficiency. Only a handful of DOTs have implemented some flavors of such initiative and reported different levels of reduction in crashes or near-crashes. The reduction in delay is relatively low, if any, in comparison to the benefits of reduction of secondary crashes. A thorough analysis and estimation for Tennessee’s unique circumstance would be a major outcome of this project. (Objective 4) Potential Benefit/Cost Estimation for Rural HELP Deployment/Expansion. The efficient response and service of HELP program is primarily deployed in the State’s four major metropolitan areas, where in 2017 lane blockage incidents were promptly cleared in less than 30 minutes some 85% of the time and less than 2% of time it took more than 90 minutes to clear. The promptness was less pronounced during the same year for the fringe/rural areas of these metropolitans where less than half of the time incidents were cleared in 30 minutes and more than 20% of the time it took more than 90 minutes [TDOT TMC/HELP Annual Report 2017]. Using the WAZE reports, which covers the entire State of Tennessee, one could identify rural areas where expansions and additional services could result in significant savings in lives and reduction in delay. The benefits and costs for these potential expansions and rural deployment will be helpful for the investment decision-making. (Objective 5) Automation for Annual B/C Analysis. It is logical to automate the preceding data-based analysis process and generate benefit/cost reports on yearly basis. This automated tool should be able to interface with the incident database and generate statistics for reporting purposes. Some flexibility for the user to modify and test different scenarios should be considered.


  • English


  • Status: Completed
  • Funding: $125000
  • Contract Numbers:


  • Sponsor Organizations:

    Tennessee Department of Transportation

    James K. Polk Building
    Fifth and Deaderick Street
    Nashville, TN  United States  37243-0349
  • Managing Organizations:

    University of Tennessee, Knoxville

    Center for Transportation Research
    Conference Center Building
    Knoxville, TN  United States  37996-4133
  • Project Managers:

    Brown, Josh

  • Performing Organizations:

    University of Tennessee, Knoxville

    Knoxville, TN  United States 
  • Principal Investigators:

    Han, Lee

  • Start Date: 20181201
  • Expected Completion Date: 20220831
  • Actual Completion Date: 20220530
  • USDOT Program: Accelerating Innovative Mobility (AIM)
  • USDOT Program: Accountability
  • USDOT Program: Advanced Research
  • USDOT Program: Highway and Transportation Data
  • USDOT Program: Human Service Coordination Research

Subject/Index Terms

Filing Info

  • Accession Number: 01771481
  • Record Type: Research project
  • Source Agency: Tennessee Department of Transportation
  • Contract Numbers: RES2019-10
  • Files: RIP, STATEDOT
  • Created Date: May 11 2021 4:09PM