Reducing Fog-Related Crashes on the Afton and Fancy Gap Mountain Sections of I-64 and I-77 in Virginia

Report No: 03-CR2

Published in 2002

About the report:

The Fancy Gap and Afton Mountain interstates have a long history of fog-related, multivehicle crashes. Because of its earlier involvement in the installation and evaluation of the original Afton Mountain in-pavement fog guide light system, and concerns about continuing fog crash problems, the Virginia Transportation Research Council (VTRC) created an expert panel made up of decision makers from the Virginia Department of Transportation (VDOT) and the Virginia Department of State Police (VSP). Personnel from the Virginia Tech Transportation Institute and VTRC staffed the panel. After detailed crash analyses, a review of the literature on fog and its effects, and an extensive survey of fog mitigation systems in the United States and abroad, the panel issued the following recommendations: (1) Install variable message signs (VMSs) immediately prior to the most fog-prone areas to warn drivers of detected incidents, fog-related vehicle stops, or slowdowns ahead. Use highway advisory radio within the fog zone to communicate with drivers. (2) Install video cameras on the Afton and Fancy Gap fog areas to allow police and VDOT officials to confirm the presence of high-density fog areas and to allow the public to better plan their travel routes. Explore the use of ultra-low temperature, infrared video cameras to penetrate fog. (3) Increase police visibility in the fog areas to improve compliance with posted speed limits and advisory limits, including increased patrols and possible staff assignments to I-77 at Fancy Gap and I-64 at Afton. (4) Seek authorization for experimental use of advisory and regulatory variable speed limits on I-77 as part of the new Fancy Gap fog mitigation system. (5) Conduct research to improve the legibility and visibility of VMSs in fog. Also, study the effectiveness of static signs augmented with strobes and lasers to warn drivers of detected incidents and slowdowns in the fog zone. Because the panel represented multiple levels of VDOT and VSP and had extensive experience with the fog problems under consideration, a wide variety of solutions were offered for consideration, and each was judged from a variety of perspectives. The result was that only practical, applicable, and highly effective solutions were chosen for implementation. Because the group had representatives with extensive technical expertise in intelligent transportation systems (ITS) to advise them, they had confidence that their recommendations would be both workable and effective. It may be that this method of building consensus and support can be used as a model to promote deployment of ITS technologies to serve site-specific safety problems.

Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.


  • Christopher Schreiner, Ross Campbell, Cheryl W. Lynn

Last updated: December 1, 2023

Alert Icon

Please note that this file is not ADA compliant. Choose one of below options: