Applications of Variable Speed Limits in Recurrent Congestion

Recurrent traffic congestion caused by volume surges in peak periods disrupts highway networks by creating bottlenecks. While network expansion would alleviate the problem, resources to do so are very limited. In consequence, transportation professionals are faced with the challenge of developing methods that mitigate congestion and improve safety under constrained budgets. One method that has shown promise is the use of variable speed limit (VSL) control systems. VSL control dynamically adjusts the speed limit on a given roadway segment with the objective of harmonizing the spatial speed transition from free-flow conditions to the congested conditions resulting from a bottleneck. Preliminary studies have shown that VSL control can delay the formation of bottlenecks and shorten the bottleneck duration. It is also expected that VSL control can also improve travel time and measures of safety through the segment if it is properly deployed. The primary objective of this research project is to develop a VSL implementation tool for highway segments plagued by recurrent congestion. The tool will include an evaluation module for evaluating the expected benefits from proper VSL deployment; an operational module that will provide guidance on the proper VSL deployment, such as the location of VSL sings and detectors; and an assessment module to analyze the results of a properly deployed VSL control system. The final product of this research will be a comprehensive toolbox that will assist in decision making, field deployment and analysis of VSL controls on recurrently congested highway segments.


    • English


    • Status: Active
    • Contract Numbers:



    • Sponsor Organizations:

      Mid-Atlantic Universities Transportation Center

      Pennsylvania State University
      201 Transportation Research Building
      University Park, PA  United States  16802-4710
    • Performing Organizations:

      University of Maryland, College Park

      College Park, MD  United States  20742
    • Principal Investigators:

      Chang, Gang-Len

    • Start Date: 20120601
    • Expected Completion Date: 0
    • Actual Completion Date: 20130531
    • Source Data: RiP Project 31798

    Subject/Index Terms

    Filing Info

    • Accession Number: 01467328
    • Record Type: Research project
    • Source Agency: Mid-Atlantic Universities Transportation Center
    • Contract Numbers: DTRT12-G-UTC03, UMD-2012-05
    • Files: UTC, RiP
    • Created Date: Jan 3 2013 3:31PM