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TRAFFIC CONTROL & ROADWAY ELEMENTS - THEIR RELATIONSHIP TO HIGHWAY SAFETY/REVISED. CHAPTER 9 INTERCHANGES

TRAFFIC ACCIDENTS IN THE VICINITY OF FREEWAY INTERCHANGES ARE INVESTIGATED WITH THE AIM OF UNDERSTANDING THE RELATIONSHIP BETWEEN INTERCHANGE DESIGN FEATURES AND TRAFFIC SAFETY. THE ANALYSIS IS CONDUCTED UNDER THE MAJOR HEADINGS STRUCTURE, RAMP, ENTRANCE TERMINAL, EXIT TERMINAL, WEAVING AREA, AND LANE ADDITION AND DROP. ACCIDENT RATES INCREASE AS THE DISTANCE TO THE INTERCHANGE DECREASES ON THE EXIT AND ENTRANCE SIDES OF INTERCHANGES IN BOTH RURAL AND URBAN LOCATIONS. RELATIVELY SAFE DESIGNS ARE PRODUCED WHEN THE RAMP TERMINALS ARE AT LEAST 750 FEET FROM THE STRUCURE. ON-RAMPS BECOME HIGH ACCIDENT LOCATIONS IN URBAN AREAS, WHILE IN RURAL AREAS THE OFF-RAMPS ARE THE GREATEST ACCIDENT PROBLEM. THE SAFETY OF ENTRANCE TERMINALS IS IMPROVED WITH GEOMETRIC DESIGNS THAT PROVIDE AUXILIARY LANES OR ACCELERATION LANES OF 800 FEET OR MORE IN LENGTH. DECELERATION LANES 800 FEET LONG OR MORE ELIMINATE TRAFFIC FRICTION ON THE THROUGH LANES AND CAUSE REDUCED ACCIDENT RATES. ADEQUATE SIGHT DISTANCES ARE ESSENTIAL AT ENTRANCE EXIT TERMINALS. GEOMETRIC DESIGNS FOR WEAVING MANEUVERS SHOULD PROVIDE WEAVING SECTIONS AT LEAST 800 FEET LONG.

  • Supplemental Notes:
    • The Automotive Safety Foundation published the first three chapters in this series. The remaining nine chapters were published by the Highway Users Federation for Safety and Mobility.
  • Corporate Authors:

    Highway Users Federation for Safety and Mobility

    1776 Massachusetts Avenue, NW
    Washington, DC  United States  20036
  • Authors:
    • Oppenlander, J C
    • Dawson, R F
  • Publication Date: 1970

Media Info

  • Features: Figures; Tables;
  • Pagination: 11 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00225921
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 3 1971 12:00AM