THE PASSING MANEUVER AS IT RELATES TO PASSING SIGHT DISTANCE STANDARDS

CURRENT AASHO DESIGN STANDARDS FOR PASSING SIGHT DISTANCE ARE BASED UPON MATHEMATICAL FORMULAS WHICH EMPLOY SEVERAL ASSUMPTIONS REGARDING DRIVER-VEHICLE CHARACTERISTICS. MANY OF THE VALUES USED IN ESTABLISHING THESE STANDARDS WERE DETERMINED FROM STUDIES CONDUCTED APPROXIMATELY THIRTY YEARS AGO. THE SUBJECT OF DRIVER JUDGMENT AND DECISION PROCESSES HAS BEEN A POPULAR RESEARCH SUBJECT DURING THE PAST DECADE. STUDIES CONDUCTED IN THIS AREA SUGGEST THAT THE ASSUMPTIONS THAT FORM THE BASIS OF EXISTING DESIGN STANDARDS MAY NOT BE APPLICABLE TO CURRENT VEHICLES AND DRIVERS. THE REPORT IS ADDRESSED TO AN EXAMINATION OF CURRENT STATE OF KNOWLEDGE CONCERNING THE PASSING MANEUVERS TO ASCERTAIN THE VALIDITY OF EXISTING PASSING SIGHT DISTANCE STANDARDS. EXAMINATION OF THE STATE-OF-THE-ART REVEALED: (1) MANY OF THE VALUES USED IN ESTABLISHING PASSING SIGHT DISTANCE DESIGN STANDARDS ARE BASED SOLELY ON STUDIES CONDUCTED BETWEEN 1938 AND 1941 AND THE CRITERIA HAVE REMAINED VIRTUALLY UNCHANGED, (2) USE OF THE 10-MPH SPEED DIFFERENTIAL IN EXTRAPOLATING PASSING SIGHT DISTANCE FOR THE HIGHER SPEED GROUPS APPEARS TO BE QUESTIONABLE, (3) USE OF ASSUMED SPEEDS SOMEWHAT LOWER THAN THE HIGHWAY DESIGN SPEED MAY NOT REPRESENT THE CRITICAL PASSING SITUATION UNDER CURRENT OPERATING CONDITIONS, (4) CLEARANCE DISTANCE UNDER CURRENT AASHO STANDARDS APPEARS TO BE SOMEWHAT SHORT, AND (5) CURRENT STRIPING SPECIFICATIONS ARE IDENTICAL TO THOSE OUTLINED IN THE 1940 AASHO POLICY FOR STRIPING NO-PASSING ZONES. STRIPING PRACTICES ESTABLISHED FOR THE 1940 ASSUMPTIONS ARE QUESTIONABLE FOR CURRENT HIGHWAY OPERATION. /AUTHOR/

  • Supplemental Notes:
    • Res Rpt 134-1, 77 PP, 16 FIG, 9 TAB, 23 REF
  • Corporate Authors:

    Texas Transportation Institute

    Texas A&M University System, 1600 E Lamar Boulevard
    Arlington, TX  United States  76011
  • Authors:
    • Weaver, G D
    • Glennon, J C
  • Publication Date: 1969-8

Subject/Index Terms

Filing Info

  • Accession Number: 00203465
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jun 22 1970 12:00AM