FOG, DRIVERS REACTION AND ACCIDENTS IN CALIFORNIA

A FOUR-YEAR STUDY WAS CONDUCTED OF FOG ACCIDENTS IN CALIFORNIA TO FIND POSSIBLE REMEDIAL MEASURES. ONE OBSERVATION WAS THAT THE STOPPING DISTANCE WAS NOT ENOUGH TO BE SAFE IN FOG. WHEN DRIVING IN FOG WITH A VISIBILITY OF SIX OR SEVEN HUNDRED FEET, ALL THE EVENTS AND CONDITIONS MUST BE APPRAISED, DECIDED, AND ACTED UPON IN LESS THAN EIGHT SECONDS IF THE VEHICLE IS MOVING AT 65 MPH. A SECOND OR TWO DIVERSION AT THE WRONG TIME MAKES A STOPPED VEHICLE OR OTHER OBSTRUCTION UNAVOIDABLE EVEN WITH SEVERAL HUNDRED FEET OF VISIBILITY. ANOTHER ASPECT OF ACCIDENT PROBLEMS THAT EMERGED WAS THAT WHILE MOST OF THE ACCIDENTS OCCURRED DURING THE MORNING PEAK HOURS, IT WAS USUALLY IN THE OFF-PEAK DIRECTION. ONE OF THE MOST DISCOURAGING FINDINGS WAS A REALIZATION THAT UNDER MOST FOG CONDITIONS, REGARDLESS OF THE CONTROL DEVICE EXERTED, DRIVERS DROVE FASTER THAN WAS WAS CONSIDERED A SAFE SPEED. THE FOG STUDY CONDUCTED BY THE CALIFORNIA TRANSPORTATION AGENCY APPROACHED THE PROBLEM FROM FOUR ASPECTS: (1) THE ROADWAY, 2) PATROL ACTIVITY, (3) PUBLIC INFORMATION, AND (4) VEHICLE AND EQUIPMENT. THE ROADWAY STUDY INVOLVED VARIABLE MESSAGE SPEED SIGNS, PAVEMENT MARKERS, EDGE LINES AND COLORED LANE LINES. OF THE FOUR TREATMENTS, THE VARIABLE MESSAGE PHASE APPEARED THE MOST PRODUCTIVE. THE SECOND APPROACH VIA INCREASED EXPOSURE EITHER OF PARKED OR OF MOVING UNITS OF THE CALIFORNIA HIGHWAY PATROL SHOWED THAT PARKED UNITS IN ADVANCE OF THE TEST SITE DID CAUSE A 4-6 MPH REDUCTION IN MEAN SPEED UNDER CERTAIN CONDITIONS, BUT UNDER OTHER VARIABLES OF DAYLIGHT AND FOG INTENSITY, THE PATROL HAD NO EFFECT. THE PUBLIC INFORMATION APPROACH DID NOT AFFECT THE CHARACTERISTICS OF DRIVING IN THE FOG.

• Supplemental Notes:
  • pp 18-22, 2 FIG, 1 TAB
• Corporate Authors:

  Itte, University of California, Berkeley

  Proceedings, 2nd Annual Symposium
  ,   United States 
• Authors:
  • Theobald, D J
• Publication Date: 1969-12

Subject/Index Terms

• TRT Terms: Crash causes; Drivers; Fog; Highways; Information dissemination; Police patrol; Reaction time; Speed; Stopping; Stopping distances; Traffic crashes; Visibility; Warning systems
• Uncontrolled Terms: Driver reaction; Stopped vehicles
• Subject Areas: Data and Information Technology; Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00220857
• Record Type: Publication
• Files: TRIS
• Created Date: Jun 1 1970 12:00AM