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COMPARISON OF ACCIDENT EXPERIENCE ON INTERSTATE AND NON- INTERSTATE HIGHWAYS--THE INFLUENCE OF HIGHWAY, TRAFFIC, AND ENVIRONMENTAL CHARACTERISTICS

A DATA-ACQUISTION PROCEDURE EMPLOYED IN A 1963 STUDY OF ACCIDENT RATES ON THE INTERSTATE HIGHWAY SYSTEM WAS USED TO COMPARE THE SAFETY RECORD OF THE IHS WITH THAT OF THE CONVENTIONAL HIGHWAYS REPLACED BY IT. THE SURVEY COVERS 39 STATES AND 7700 MILES OF INTERSTATE ROADS. THE PRINCIPAL FINDINGS OF THE STUDY WERE AS FOLLOWS: (1) THE ACCIDENT, INJURY, AND FATALITY RATES ON URBAN SECTIONS OF THE IHS ARE, RESPECTIVELY, 30, 61, AND 76% OF COMPARABLE RATES ON CONVENTIONAL URBAN HIGHWAYS EXISTING BEFORE THOSE SECTIONS WERE OPENED TO TRAFFIC. (2) THE VARIABLE THAT CONTRIBUTED MOST TO THE VARIANCE OBSERVED IN ACCIDENTS WAS ACCESS CONTROL: WHERE IT WAS ABSENT, THE ACCIDENT RATE INVARIABLY INCREASED. (3) A MATHEMATICAL MODEL IN WHICH ACCESS CONTROL AND ACCIDENT RATES WERE CORRELATED REVEALED THAT THE NUMBER OF AT-GRADE INTERSECTIONS PER MILE AND THE NUMBER OF BUSINESSES WITH DIRECT ACCESS TO THE HIGHWAY PER MILE WERE SIGNIFICANT VARIABLES IN EVERY NON- INTERSTATE MODEL. (4) ON IHS ROADS THE RELATIONSHIP BETWEEN ACCIDENT RATE AND TRAFFIC VOLUME WAS CURVILINEAR RATHER THAN LINEAR, I.E., ACCIDENT RATES DECREASED WITH INCREASING ADT UP TO A POINT AND THEN INCREASED. THE SAME RELATIONSHIP EXISTED ON THE CONVENTIONAL ROADS, BUT WAS LESS DISCERNABLE OWING TO VARIATIONS IN ACCESS CONTROL AND THE EXISTENCE OF MEDIANS ON THE IHS. IN RURAL AREAS THE OPENING OF INTERSTATE ROADS HAD A NEGLIGIBLE EFFECT ON THE ACCIDENT RATE OF CONVENTIONAL HIGHWAYS. (5) ON THE IHS HEAD-ON ACCIDENTS HAVE BEEN VIRTUALLY ELIMINATED, AND ANGLE COLLISIONS, GREATLY REDUCED. SINGLE-VEHICLE COLLISIONS ARE THE PREDOMINATE ACCIDENT TYPE ON RURAL IHS ROADS, REAR-END COLLISIONS ON URBAN ONES. (6) IN 1975 IT IS ESTIMATED THAT THE 41,000 MILES OF THE IHS WILL SAVE APPROXIMATELY 7500 LIVES, 347,000 INJURIES, 823,000 ACCIDENTS, AND $250 MILLION IN PROPERTY DAMAGE. ADDITIONAL SAVINGS WILL BE PROVIDED BY THE 1500 MILES RECENTLY ADDED TO THE SYSTEM.

  • Supplemental Notes:
    • Vol 1, 60 PP, FIG, TAB, 3 APP
  • Corporate Authors:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • FEE, J A
    • Beatty, R L
    • Dietz, S K
    • Kaufman, S F
    • Yates, J G
  • Publication Date: 1970-10

Subject/Index Terms

Filing Info

  • Accession Number: 00221231
  • Record Type: Publication
  • Files: TRIS, USDOT
  • Created Date: Apr 25 1971 12:00AM