DRIVER EYE HEIGHT AND RELATED HIGHWAY DESIGN FEATURES

THE TREND IN RECENT YEARS TOWARD LOWER VEHICLES HAS RESULTED IN A GRADUAL REDUCTION OF THE HEIGHT OF THE DRIVER'S EYES ABOVE THE SURFACE OF THE ROADWAY AND A CONSEQUENTIAL RESTRICTION OF SIGHT DISTANCE IN MANY SITUATIONS. REPRESENTATIVE DIMENSIONS FOR DRIVER EYE HEIGHT AND FOR OVER-ALL VEHICLE HEIGHT ARE USED BY THE HIGHWAY DESIGNER IN CALCULATING SAFE SIGHT DISTANCES ON VERTICAL CURVES AND IN PROVIDING ADEQUATE HORIZONTAL SIGHT DISTANCES AT CRITICAL LOCATIONS. A STUDY OF SOME 2,000 LARGE-FORMAT PHOTOGRAPHS SHOWING DRIVERS AND VEHICLES OPERATING AT NORMAL ROAD SPEEDS AND UNDER ORDINARY DRIVING CONDITIONS HAS BEEN CONDUCTED FOR THE PURPOSE OF DETERMINING UP-TO-DATE INFORMATION ON EYE HEIGHT AND VEHICLE HEIGHT WHICH CAN BE USED FOR DESIGN PURPOSES. DATA FROM THIS STUDY ARE PRESENTED TO SHOW THE MAGNITUDE OF THE DOWNWARD TREND IN HEIGHTS, TO PROVIDE A MEASURE OF THE RANGE IN DIMENSIONS RESULTING FROM MANY VARIABLES IN VEHICULAR AND DRIVER CHARACTERISTICS, AND TO ESTABLISH A BASIS FOR THE SELECTION OF REPRESENTATIVE DESIGN QUANTITIES. CHARTS SHOWING LENGTHS OF VERTICAL CURVES REQUIRED TO PROVIDE PASSING AND NONPASSING SIGHT DISTANCES FOR VARIOUS COMBINATIONS OF SPEED AND GRADE ARE USED TO SHOW THE EFFECT OF LOWERING DRIVER EYE POSITION AND OVER-ALL VEHICLE HEIGHT FROM THE CURRENTLY RECOMMENDED HEIGHT OF 4.5 FT TO A DIMENSION SOMEWHAT LESS THAN 4 FT, A HEIGHT DETERMINED TO BE REPRESENTATIVE OF PASSENGER CARS OPERATING ON THE STREETS AND HIGHWAYS TODAY. THESE CHARTS, DERIVED FROM ACCEPTED METHODS OF CALCULATION OF SIGHT DISTANCES, MAY BE USED FOR DESIGN PURPOSES. FOR DRIVERS WHOSE EYES ARE LESS THAN 4 FT FROM THE ROADWAY SURFACE, HORIZONTAL SIGHT DISTANCE IS RESTRICTED AT MANY LOCATIONS BY STATIONARY OBJECTS SUCH AS GUARDRAILS, WING WALLS, AND PARKED VEHICLES. MOVING VEHICLES LIKEWISE OBSTRUCT HORIZONTAL VISIBILITY IN CERTAIN TRAFFIC MERGING AREAS. PHOTOGRAPHS ARE USED TO ILLUSTRATE SOME OF THESE PROBLEM AREAS WHICH HAVE BEEN CREATED BY REDUCING DRIVER EYE HEIGHT. THROUGH NOMINAL CHANGES IN DESIGN, HIGHWAY ENGINEERS CAN VIRTUALLY ELIMINATE THE PROBLEM AREAS IN FUTURE DESIGNS BY RECOGNIZING QUANTITATIVELY AS WELL AS QUALITATIVELY THE EFFECT OF LOWER DRIVER EYE HEIGHT ON HORIZONTAL SIGHT DISTANCE. /AUTHOR/

  • Supplemental Notes:
    • Vol 39, pp 46-60, 6 FIG, 9 PHOT, 3 REF
  • Authors:
    • Lee, C E
  • Publication Date: 1960

Media Info

  • Monograph Title: Proceedings of the Thirty-Ninth Annual Meeting of the Highway Research Board, Washington, D.C., January 11-15, 1960
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00203573
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 29 1971 12:00AM