GUARDRAIL PERFORMANCE AND DESIGN

BARRIER INSTALLATIONS ARE WARRANTED (OR JUSTIFIED) ONLY AT HIGHWAY LOCATIONS WHERE THE CONSEQUENCE OF AN ERRANT VEHICLE LEAVING THE ROADWAY IS JUDGED TO BE MORE HAZARDOUS THAN THE IMPACT WITH THE BARRIER INSTALLATION. A SIX DEGREE-OF-FREEDOM MATHEMATICAL MODEL WAS FOUND TO BE USEFUL IN DESCRIBING DYNAMIC BEHAVIOR OF A VEHICLE DURING IMPACT. PREDICTIONS OF VEHICLE AND BARRIER BEHAVIOR CORRELATED WITH RESULTS OBTAINED FROM FULL-SCALE CRASH TESTS. CRASH CONDITIONS SIMULATED WITH A COMPUTER WERE USED TO IDENTIFY AND EVALUATE VEHICLE STATIC AND DYNAMIC AS WELL AS BARRIER PARAMETERS. VEHICLE WEIGHT, YAW MASS MOMENT OF INERTIA, AND DEFORMATION CONSTANT WERE FOUND TO BE SIGNIFICANT. AS EXPECTED, SUCH VEHICLE DYNAMIC PARAMETERS AS IMPACT SPEED AND ANGLE WERE THE MOST IMPORTANT FACTORS IN VEHICLE-GUARDRAIL INTERACTION. THE SIGNIFICANT BARRIER PARAMETERS WERE ASCERTAINED TO BE THOSE RELATED TO POST STRENGTH, VEHICLE-BARRIER COEFFICIENT OF FRICTION, SOIL MODULUS, AND BEAM TENSION; THESE APPRECIABLY INFLUENCE THE ACCELERATION INTENSITIES INDUCED IN THE VEHICLE DURING REDIRECTION. FOR THE SYSTEMS EXAMINED, IT WAS FOUND THAT VEHICLE LATERAL ACCELERATIONS WERE HIGHER WITH RESPECT TO SUGGESTED HUMAN TOLERANCE LEVELS THAN THE LONGITUDINAL ACCELERATIONS WITH RESPECT TO THEIR CORRESPONDING SUGGESTED LEVELS. FOR A STANDARD TEST (I. E., 4000-LB. VEHICLE, 60 MPH, AND 25-DEGREE IMPACT), THE VEHICLE ACCELERATION PREDICTIONS WHEN COMPARED TO SUGGESTED HUMAN TOLERANCE LEVELS INDICATE THAT OCCUPANTS NEED BOTH LAP BELT AND CHEST HARNESS RESTRAINTS TO AVOID SERIOUS INJURIES. TO FACILITATE COMPARISONS OF BARRIER SYSTEMS ON THE BASIS OF DYNAMIC PERFORMANCE, THE ORDER IN WHICH THE THREE MOST SIGNIFICANT FACTORS NEED BE CONSIDERED WAS ESTABLISHED AS BEING: (1) BARRIER STRUCTURAL INTEGRITY AS DETERMINED WHETHER OR NOT A SYSTEM CAN REDIRECT A SELECTED ERRANT VEHICLE, (2) VEHICLE ACCELERATIONS DURING REDIRECTION, AND (3) POST-IMPACT TRAJECTORY OF THE VEHICLE. FOR SYSTEMS THAT SATISFY THIS BASIC REQUIREMENT THE EVALUATION PROCEDURE NEXT CONSIDERS VEHICLE ACCELERATIONS; THESE VEHICLE ACCELERATION VALUES SERVE AS INDICATORS OF THE SEVERITY OF REDIRECTION AND MAY BE USED IN PROJECTING POSSIBLE INJURIES OR FATALITIES AMONG VEHICLE OCCUPANTS. FINALLY, WHEN THE FIRST TWO FACTORS ARE EQUAL OR ACCEPTABLE, VEHICLE EXIT TRAJECTORY BECOMES A CRITICAL CRITERION AS IT REFLECTS THE HAZARDS PRESENTED TO OTHER TRAFFIC. THE REBOUNDING VEHICLE CAN BE THE CAUSE OF A MULTICAR COLLISION, ALTHOUGH THE INCIDENCE OF THIS IS CONJECTURED TO BE QUITE SMALL /NCHRP/

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  • Supplemental Notes:
    • Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved. Proj 15-1(2), 70 PP, 55 FIG, 30 TAB, 3 APP
  • Authors:
    • Michie, J D
    • Calcote, L R
    • Bronstad, M E
  • Publication Date: 1971

Media Info

  • Media Type: Digital/other
  • Serial:
    • NCHRP Report
    • Issue Number: 115
    • Publisher: Transportation Research Board
    • ISSN: 0077-5614
  • Publication flags:

    Open Access (libre)

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Filing Info

  • Accession Number: 00203585
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Oct 3 1971 12:00AM