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SOME RELATIONSHIPS BETWEEN ROAD ACCIDENT FREQUENCIES AND MEASURES OF EXPOSURE TO RISK

THE OBJECTIVE IS TO PRODUCE SOME PRELIMINARY EVIDENCE FOR A THEORY OF ROAD ACCIDENT OCCURRENCE, BY INVESTIGATION OF RELATIONSHIPS BETWEEN NUMBERS OF ROAD ACCIDENTS AND MEASURES OF EXPOSURE TO RISK. METHODS USED IN THE INVESTIGATION INCLUDE THE COMPARISON OF ACTUAL ACCIDENT FREQUENCIES WITH EXPECTED VALUES OBTAINED BY DISTRIBUTING THE TOTAL NUMBER OF ACCIDENTS IN VARIOUS WAYS, AND WITH MEASURES OF EXPOSURE BASED ON THE TRAFFIC MOVEMENTS THAT WOULD BE EXPECTED TO BE ASSOCIATED WITH THE ACTUAL NUMBER OF ACCIDENTS. OTHER METHODS USED INCLUDE STUDIES OF THE EFFECTS ON THE PROBABILITY OF SUCH VARIABLES AS TRAFFIC FLOW, DARKNESS, AND ROAD DESIGN. THE RESULTS, SOME NEW AND OTHERS MAKING USE OF PREVIOUS FINDINGS, ARE VARIED BUT MAY BE GROUPED INTO THREE CATAGORIES. IN ONE ARE RESULTS ABOUT THE RELATIONSHIPS BETWEEN ACCIDENTS AND MEASURES OF EXPOSURE: FOR EXAMPLE, TEN STUDIES SHOW THAT THE NUMBER OF ACCIDENTS PER VEHICLE TRAVELLING ALONG A LENGTH OF ROAD IS MUCH THE SAME OVER A WIDE RANGE OF FLOWS, BUT THREE OF THESE SUGGEST THAT THE NUMBER IS HIGHER AT LOWER FLOWS. IN ANOTHER GROUPS ARE FINDINGS ABOUT METHODS OF ANALYSIS, SUCH AS THE CONCLUSION THAT THE ACCIDENT RATE AT URBAN CROSS ROADS IS TWICE THAT AT URBAN T- OR Y-JUNCTIONS, IRRESPECTIVE OF WHETHER THE RATIO ACCIDENTS/SUM OF ENTERING FLOWS OR THE RATIO ACCIDENTS/SQUARE ROOT OF PRODUCT OF ENTERING FLOWS IS USED TO DEFINE ACCIDENT RATE. THE THIRD GROUP CONTAINS COMPARISONS BETWEEN OBSERVED AND THEORETICALLY EXPECTED FREQUENCIES: A RESULT OF THIS TYPE IS THAT THE NUMBERS OF ACCIDENTS IN DIFFERENT LENGTHS OF ROAD SECTIONS CAN FOLLOW THE POISSON OR THE NEGATIVE BINOMIAL DISTRIBUTION, ACCORDING TO THE VARIATION OF THE EXPECTED NUMBERS AMONG THE SECTIONS. A REVIEW OF PERTINENT LITERATURE, SUGGESTIONS FOR FURTHER RESEARCH, AND A BIBLIOGRAPHY ARE INCLUDED. /AUTHOR/

  • Corporate Authors:

    University College London

    London,   United Kingdom 
  • Authors:
    • Chapman, R A
  • Publication Date: 1971-1

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 338 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00222106
  • Record Type: Publication
  • Source Agency: Nat Safety Council Safety Res Info Serv
  • Files: TRIS
  • Created Date: Jul 17 1973 12:00AM