DEVELOPMENTS IN THE STRUCTURAL DESIGN OF FLEXIBLE ROAD PAVEMENTS

THIS PAPER REVIEWS THE DEVELOPMENT OF STRUCTURAL DESIGN STANDARDS FOR ROADS IN BRITAIN SINCE 1945 AND GIVES BRIEF DETAILS OF THE CONTENT OF THE FIRST AND SECOND EDITIONS OF ROAD NOTE 29, PUBLISHED IN 1960 AND 1965. THE PREPARATION OF THE THIRD EDITION, PUBLISHED IN 1970, IS CONSIDERED IN MORE DETAIL. THE PRINCIPAL CHANGE RELATES TO THE METHOD ADOPTED TO DEFINE TRAFFIC. THE AXLE LOADS ASSOCIATED WITH COMMERCIAL TRAFFIC HAVE BEEN STUDIED ON A VARIETY OF ROADS, USING PERMANENTLY INSTALLED WEIGHBRIDGES. THE DAMAGING POWER HAS BEEN EXPRESSED IN TERMS OF REPETITIONS OF A 'STANDARD' 8200 KG (18000 LB) AXLE USING THE AASHO ROAD TEST EQUIVALENCE FACTORS. IN THIS WAY ALLOWANCE IS MADE FOR THE INCREASE IN AXLE LOADING WHICH TENDS TO OCCUR AS THE VOLUME OF COMMERCIAL TRAFFIC INCREASES. A SERIES OF CHARTS RELATES THE CUMULATIVE NUMBER OF STANDARD AXLES CARRIED BY EACH SLOW TRAFFIC LANE TO THE INITIAL COMMERCIAL TRAFFIC FLOW, THE TRAFFIC GROWTH RATE AND THE DESIGN LIFE. THE DESIGN THICKNESSES FOR SUB-BASE, BASE AND SURFACING ARE ALSO DEFINED BY GRAPHS IN TERMS OF THE CUMULATIVE NUMBER OF STANDARD AXLES TO BE CARRIED DURING THE DESIGN LIFE. A MAJOR ADVANTAGE OF THE NEW METHOD OF PRESENTATION IS THE INCLUSION OF DESIGN LIFE AS A VARIABLE. THE IMPLICATIONS IN TERMS OF PAVEMENT THICKNESS AND CONSTITUTION OF INCREASING OR DECREASING THE DESIGN LIFE CAN BE READILY SEEN. /RRL/

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Filing Info

  • Accession Number: 00205674
  • Record Type: Publication
  • Source Agency: Road Research Laboratory /UK
  • Files: TRIS
  • Created Date: Apr 23 1972 12:00AM