The California Highway patrol (CHP) and the Department of Transportation (Caltrans) cooperated in the Fog Sign Study to determine the usefulness of "changeable message" warning signs in dense fog. The study was conducted in Stockton Area on SR 99 south of Stockton and in Riverside Area on SR 91 near Corona. The time period for the study was December 1, 1976, through March 31, 1977. Five warning signs (48" x 48") with telescoping stand and strobe light were assigned to each Area. Two cloth changeable messages were used: "DENSE FOR AHEAD" and "WRECK AHEAD". These messages were attached to a basic sign by means of velcro fasterners and could be easily changed to meet operational needs. The signs were collapsible so they could fit in the trunk of the patrol car. When there was an accident in light to heavy fog, the CHP patrol unit put up the warning sign with the message, "WRECK AHEAD". To prevent potential chain reaction accidents, the other warning sign with the message "DENSE FOG AHEAD" was put up whenever there was a fog bank ahead of 200 feet or less visibility. The intent of the study was to determine what effect the warning signs ("DENSE FOG AHEAD" and "WRECK AHEAD") hand on vehicle speed. Also, the practicality and the usefulness of the signs were to be determined through comments made by CHP Officers. Objective analysis could not be made because of lack of data. Speed surveys were not conducted, and only eight "Warning Sign Evaluation Forms" were completed. It is recommended that the usefulness and effectiveness of these fog signs be restudied during the 1977 fog season with improvements. /Authors/

  • Corporate Authors:

    California Highway Patrol

    Planning and Analysis Division, P.O. Box 942898
    Sacramento, CA  United States  94298-0001
  • Publication Date: 1977-5

Media Info

  • Pagination: 15 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00195403
  • Record Type: Publication
  • Source Agency: National Safety Council Safety Research Info Serv
  • Report/Paper Numbers: Intrm Rpt.
  • Files: TRIS
  • Created Date: Aug 15 1979 12:00AM