DRIVING IN FOG

DATA WERE COLLECTED ON A WESTBOUND PORTION OF NEW YORK STATE ROUTE 17 TO INVESTIGATE THE EFFECTS OF FOG ON DRIVERS. THE ROAD WAS A FOUR LANE DIVIDED HIGHWAY SEPARATED BY A TREELESS MEDIAN ABOUT 35 FEET WIDE. THERE WAS A SIGNAL-CONTROLLED INTERSECTION 1.1 MILES UPSTREAM OF THE TEST SIGHT WHICH INDUCED SOME PLATOONING AMONG THE OBSERVED VEHICLES. THERE WAS AN INTERSECTION .7 MILES DOWNSTREAM OF THE SITE WITH TWO WAY SIGNS CONTROLLING CROSS TRAFFIC. VEHICLE SPEEDS, ARRIVAL TIMES, AND LATERAL PLACEMENT WERE DETERMINED BY USING THREE INFRARED LIGHT BEAMS IN A REVERSED LETTER N CONFIGURATION. THE DIAGONAL BEAM WAS USED FOR THE DETERMINATION OF LATERAL LOCATION. DATA WERE COLLECTED UNDER NIGHT, DAWN, AND DAYLIGHT CONDITIONS ON EACH OF SIX DAYS. VISUAL DISTANCE WAS MEASURED AS THE MAXIMUM RANGE AT WHICH LEAD VEHICLES COULD BE SEEN. OF THREE WAYS IN WHICH DRIVERS ARE CAPABLE OF MANIPULATING THEIR RELATIONSHIPS WITH OTHER VEHICLES (SPACING, HEADWAY, AND COLLISION COURSE TIME), NONE WAS SEEN TO BE INFLUENCED BY FOG. VARIANCES OF SERVERL MEASURES WERE STUDIED TO SEE IF FOG AFFECTED UNIFORMITY OF FLOW. THE MEASURES INCLUDED LATERAL PLACEMENT, VEHICLE SPACING, TIME HEADWAYS AND SPEED. NONE OF THESE CHANGED SYSTEMATICALLY WITH FOG LEVEL. THE ONE VARIABLE WHICH WAS INFLUENCED BY FOG WAS VEHICLE SPEED. STUDY OF TRAFFIC ACCIDENT DATA AND FOG SUGGEST TWO MECHANISMS WHICH OPERATE IN FOG: (1) THE DELAY IN RESPONDING DUE TO THE INABILITY TO SEE AHEAD APPEARS TO AFFECT THE SEVERITY OF ACCIDENTS, AND (2) THE CARE EXHIBITED BY DRIVERS IN FOG IS RELATED DIRECTLY TO THE DRIVER'S ESTIMATE OF THE LIKELIHOOD OF INTERACTIONS WITH OTHER VEHICLES. THE STUDY SHOWS THAT IT APPEARS THAT DRIVERS ARE AWARE OF FOG AS A HAZARD BUT THEY SEEM EITHER NOT TO KNOW HOW TO, OR TO BE WILLING TO, OVERTLY RESPOND IN WAYS OTHER THAN MODEST SPEED REDUCTIONS. DATA SHOW THAT THE SPEED REDUCTIONS ARE INSUFFICIENT TO PRECLUDE EXCESSIVE OVERDRIVING. THE PROBLEM IS MOST SEVERE UNDER CONDITIONS OF OVER-CONFIDENCE ASSOCIATED WITH LIMITED ACCESS HIGHWAYS.

• Supplemental Notes:
  • pp 7-10, 1 FIG, 1 TAB, 8 REF
• Corporate Authors:

  Itte, University of California, Berkeley

  Proceedings, 2nd Annual Symposium
  ,   United States 
• Authors:
  • PERCHONOK, K
• Publication Date: 1969-12

Subject/Index Terms

• TRT Terms: Crash analysis; Crash rates; Crash severity; Data collection; Distance; Divided highways; Drivers; Fog; Four lane highways; Freeways; Infrared radiation; Lateral placement; Speed; Traffic crashes; Vehicles
• Subject Areas: Highways; Safety and Human Factors; Vehicles and Equipment;

Filing Info

• Accession Number: 00220855
• Record Type: Publication
• Files: TRIS
• Created Date: Jun 1 1970 12:00AM