MINIMIZING THE HAZARD OF RESTRICTED VISIBILITY IN FOG - WITH DISCUSSION

THE PAPER DESCRIBES THE NATURE OF FOG AND ITS FORMATION, THE EFFECTS OF FOG AND ACCIDENTS, CURRENT FOG ABATEMENT TECHNIQUES, AND POSSIBLE GUIDANCE SYSTEMS TO AID DRIVERS IN MINIMIZING THE HAZARDS ENCOUNTERED IN FOG. STUDIES HAVE REVEALED THAT FOR CONVENTIONAL ROADS, FOG (WHICH REDUCES THE VISUAL RANGE TO LESS THAN 3,300 FT.) REDUCES THE ACCIDENT RATE BY 6 TO 10 PERCENT WITH THE LARGEST REDUCTION IN THE MORE SEVERE CATEGORIES OF ACCIDENTS. THIS EFFECT IS ATTRIBUTED TO THE DRIVER'S AWARENESS OF FOG AS A HAZARD. STUDIES ON FREEWAYS, HOWEVER, REVEAL THAT FATALITY RATE FOR FOG ACCIDENTS IS TWICE THAT OF NON-FOG ACCIDENTS; THE PROBABILITY OF MULTIPLE-VEHICLE ACCIDENT IS GREATER; AND FOG DOES NOT HAVE MUCH EFFECT ON THE MEAN NUMBER OF VEHICLES PER ACCIDENT BECAUSE THERE WERE ALSO MORE SINGLE VEHICLE ACCIDENTS IN FOG. FOG ABATEMENT TECHNIQUES REVIEWED INCLUDE DRY-ICE SEEDING, REDUCING THE INDUSTRIAL POLLUTION, AND THERMAL, ELECTRICAL AND MECHANICAL FOG DISPERSAL TECHNIQUES. THE LIMITED UTILITY OF PORTABLE DISPERSAL EQUIPMENT, AND NATURAL VEGETATION BARRIERS THAT PREVENT THE DRIFTING OF SHALLOW FOGS ARE ALSO DISCUSSED. DIRECTIONAL TYPES OF FIXED-LIGHTING SYSTEMS HAVE PROVED EFFECTIVE IN PROVIDING GUIDANCE IN NIGHTTIME FOG. REFLECTORIZED PAVEMENT MARKINGS AND REAR VEHICLE LIGHTING SYSTEMS ARE INEFFECTIVE IN DAYTIME FOG. VARIABLE MESSAGE SIGNS THAT WARN DRIVERS OF FOG CONDITIONS AHEAD AND INDICATE SPEED REQUIREMENTS ARE CONSIDERED THE MOST DESIRABLE. AN ADVISORY SYSTEM THAT WILL INFORM DRIVERS OF THE STATUS OF OTHER VEHICLES' SPEEDS ON THE ROAD AHEAD BEYOND THE LIMIT OF THE DRIVERS SIGHT IS CURRENTLY BEING DEVELOPED. THE VARIABLE NATURE OF DIFFERENT TYPES OF FOG AND THE NEED TO STUDY THE SPECIFIC PROBLEM IS STRESSED IN THE DISCUSSION.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/sr/sr134/sr134-003.pdf
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0309020972
• Supplemental Notes:
  • Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
• Corporate Authors:

  Highway Research Board

  2101 Constitution Avenue, NW
  Washington, DC    20418
• Authors:
  • Schwab, R N
• Discussers:
  • Heiss, W H
  • Hofstetter, Dwayne
• Conference:
  • Workshop on Highway Visiblity
  • Location: St Paul Minnesota, United States
  • Date: 1972-7-18 to 1972-7-20
• Publication Date: 1973

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: pp 19-27
• Monograph Title: HIGHWAY VISIBILITY
• Serial:
  • Highway Research Board Special Report
  • Issue Number: 134
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Crash rates; Crash severity; Fatalities; Fog; Fog dispersal; Guide signs; Hazards; Lighting; Pollution; Speed; Vegetation; Visibility; Warning signs
• Uncontrolled Terms: Dry ice; Hazard perception
• Subject Areas: Environment; Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00222185
• Record Type: Publication
• ISBN: 0309020972
• Files: TRIS, TRB, ATRI
• Created Date: Apr 20 1974 12:00AM