• Skip to primary navigation
  • Skip to main content
Logo

Work Zone Safety Information Clearinghouse

Library of Resources to Improve Roadway Work Zone Safety for All Roadway Users

  • About
  • Newsletter
  • Contact
  • X
  • Facebook
  • LinkedIn
  • Work Zone Data
    • At a Glance
    • National & State Traffic Data
    • Work Zone Traffic Crash Trends and Statistics
    • Worker Fatalities and Injuries at Road Construction Sites
  • Topics of Interest
    • Commercial Motor Vehicle Safety
    • Smart Work Zones
    • Work Zone Safety and MobilityTransportation Management Plans
    • Accommodating Pedestrians
    • Worker Safety and Welfare
    • Project Coordination in Work Zones
  • Training
    • Flagger
    • Online Courses
    • Toolboxes
    • FHWA Safety Grant Products
    • Certification and
      Accreditation
  • Work Zone Devices
  • Laws, Standards & Policies
  • Public Awareness
  • Events
  • About
  • Contact
  • Search
Publication

Variable Speed Limit Sign: Effects on Speed and Speed Variation in Work Zones

Author/Presenter: Riffkin, Matt; McMurtry, Thomas; Heath, Suellen; Saito, Mitsuru
Abstract:

Variable Speed Limit (VSL) signs are used across the country in conjunction with Intelligent Transportation Systems to lower posted speed limits in areas affected by conditions such as congestion, construction, accidents, fog, snow, and ice. VSL signs let operators adjust the posted speed limit without changing the physical sign. As technology advances, the ease of using VSL signs is also increasing since speeds can now be changed at preset times via email or telephone, or manually at the site. The Utah Department of Transportation desired to evaluate the effectiveness of this technology on driver behavior before using it widely in work zones on state highways. The focus of this research is driver response to VSL signs. A six-mile test site with a long-distance work zone on I-80 north of Wanship, Utah, was used to test the response of drivers to VSL signs. Five speed detectors and two VSL signs were placed and vehicle speeds were monitored for about 3 months. The speed data analyses showed that driver response was positive. Though the average speeds between static speed limit signs and VLS signs were not statistically different at a 95% confidence level, variation in speeds was reduced in general, especially at the first speed detector location downstream of the first VSL sign. Providing drivers with speed restrictions that reflect actual conditions builds “trust” in the posted speed. Long-term use of VSL signs is recommended for evaluating their long-term effect on driver compliance to reduced work zone speed limits.

Publisher: Utah Department of Transportation
Publication Date: November 15, 2008
Notes:

The clearinghouse has a copy of this item.

Publication Types: Books, Reports, Papers, and Research Articles
Topics: Intelligent Transportation Systems; Speed Limits; Variable Speed Limit Systems

Copyright © 2025 American Road & Transportation Builders Association (ARTBA). The National Work Zone Safety Information Clearinghouse is a project of the ARTBA Transportation Development Foundation. It is operated in cooperation with the U.S. Federal Highway Administration and Texas A&M Transportation Institute. | Copyright Statement · Privacy Policy · Disclaimer
American Road and Transportation Builders Association Transportation Development Foundation, American Road and Transportation Builders Association U.S. Department of Transportation Federal Highway Administration Texas A&M Transportation Institute