ACCIDENT - EXPOSURE INDEX /WITH DISCUSSION/

THE CONVENTIONAL METHOD OF PORTRAYING TRAFFIC MOVEMENTS AT HIGHWAY INTERSECTIONS IS BY MEANS OF TRAFFIC VECTORS. WHEN TWO HIGHWAYS CROSS AT GRADE, THE VECTOR DIAGRAM CONTAINS 16 VECTOR CROSSING POINTS WHICH ARE DEFINED AS COLLISION POINTS. THE NUMBER OF THESE COLLISION POINTS IS REDUCED TO ZERO UNDER TWO CONDITIONS ONLY: WHEN A GRADE-SEPARATION STRUCTURE IS CONSTRUCTED WITHOUT INTERCHANGE RAMPS AND WHEN IT IS CONSTRUCTED WITH A FULL CLOVERLEAF OR DIRECT- CONNECTION DESIGN. WHEN TRAFFIC DENSITIES OR ECONOMIC, TOPOGRAPHIC OR URBAN-PLANNING CONSIDERATIONS INDICATE THAT A PARTIAL-INTERCHANGE LAYOUT IS CALLED FOR, IT IS MOST DESIRABLE THAT THAT TRAFFIC PATTERN AND PARTIAL-INTERCHANGE LAYOUT WHICH WILL OFFER THE GREATEST TRAFFIC EFFICIENCY BE ADOPTED. USING ONLY THE ORIGINAL TRAFFIC-VECTOR DIAGRAM AS A BASE, THE REPORT PRESENTS A TECHNIQUE WHEREBY A NUMERICAL VALUE OR SCORE IS ESTABLISHED FOR EACH LAYOUT UNDER CONSIDERATION. THIS VALUE IS TERMED THE ACCIDENT-EXPOSURE INDEX. A COMPARISON OF THESE INDICES PROVIDES A DIRECT EVALUATION OF THE TRAFFIC EFFICIENCY OF THE INTERCHANGE. COMPUTATIONS ARE GIVEN IN THIS REPORT TO EXEMPLIFY THE TECHNIQUE USED IN ESTABLISHING THE LAYOUT FOR EXPRESSWAY INTERCHANGES. /AUTHOR/

  • Supplemental Notes:
    • Vol 33, pp 129-138, 18 FIG
  • Authors:
    • Grossman, L
    • Normann, O K
  • Publication Date: 1954

Media Info

  • Monograph Title: Proceedings of the Thirty-Third Annual Meeting of the Highway Research Board, Washington, D.C., January 12-15, 1954
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00221332
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 16 1972 12:00AM