Variable advisory speed limit (VASL) systems encourage drivers to slow down gradually as they approach rural work zones.

An investigation of work zone traffic control in Missouri

I-270,St. Louis,Missouri,United States

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Lesson Learned

The following recommendations were based on the case studies investigated.
  • Use VASL systems to lower speeds and achieve better compliance with posted speed limits in areas without congestion in urban work zones.
  • Use VASL systems to complement static speed limit signs in areas without congestion in rural work zones. This can lead to safer traffic conditions by encouraging drivers to slow down gradually as they approach work areas.
  • Use simulation modeling to optimize VASL system algorithms. A well designed VASL algorithm, like the 5-minute (P5) algorithm developed in this study can improve mobility and safety in congested work zones.

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Evaluation of Variable Advisory Speed Limits in Work Zones

Author: Edara, P.; C. Sun; and Y. Hou

Published By: Iowa DOT and U.S. DOT FHWA

Prepared by University of Missouri-Columbia

Source Date: 08/01/2013

URL: http://publications.iowa.gov/14932/1/IA_DOT_TPF-5-081_InTrans_variable_advisory_speeds.pdf

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Lesson ID: 2014-00678