Lesson

Pavement friction sensors should target travel lanes instead of shoulder areas where wet pavement can persist causing VSL systems to reduce traffic speeds without need.

Experience using pavement friction sensors to trigger variable speed limit (VSL) systems in Texas.


08/09/2015
Ranger; Texas; United States; San Antonio; Texas; United States; Temple; Texas; United States


Background (Show)

Lesson Learned

Lessons learned during the three month pilot project in Texas included the following:
  • Pavement friction sensors should target travel lanes instead of shoulder areas where wet pavement can persist causing VSL systems to reduce traffic speeds without need. Friction detectors were used to help determine speed limits during wet conditions, but they were typically pointed at the shoulder. If pointed at travel lanes regular speed limits may have been restored sooner because those lanes dried faster.
  • Assure VSL signs that resemble fixed roadside speed limit signs have bright LEDs. During this pilot, the LEDs used to display speed limits had to be replaced shortly after deployment because they were not bright enough.
  • If radar detectors and VSL signs are installed at the same location understand that the effects of the VSL system on traffic speeds may not be immediately detected which may affect system performance.
  • Deploy cameras to verify the operation of VSL signs.
  • Deploy failure resistant communication pathways to ensure consistent VSL operations.


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Source

Texas Variable Speed Limit Pilot Project

Author: Randolph, Lynne (Southwestern Research Institute)

Published By: 2015 National Rural Intelligent Transportation Systems Conference

Source Date: 08/09/2015

URL: http://www.nationalruralitsconference.org/wp-content/uploads/2015/08/Randolph_S3.pdf

Lesson Contacts

Lesson Analyst:

Mike Mercer
Noblis
(202) 863-3646
michael.mercer@noblis.org


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Lesson ID: 2016-00730