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.
Lesson Categories
States
Countries
Systems Engineering
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Goal Areas
Keywords
VSL, managed lanes
Lesson ID: 2016-00730
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