A REPORT ON THE DESIGN OF THE STRUCTURAL SECTION OF CITY AND COUNTY ROADS

IN 1963, A REVISED THICKNESS DESIGN FORMULA FOR FLEXIBLE PAVEMENTS WAS INTRODUCED BY THE CALIFORNIA DIVISION OF HIGHWAYS. THIS FORMULA CONSIDERS THE STRENGTH OF THE PAVEMENT STRUCTURE, THE EFFECT OF THE SUPPORTING SOIL AND THE DESTRUCTIVE EFFECT OF TRAFFIC. THE DESTRUCTIVE EFFECT OF TRAFFIC IS EXPRESSED IN TERMS OF THE NUMBER OF PASSAGES OF A 5,000-POUND WHEEL LOAD WHICH IS EQUIVALENT, IN DESTRUCTIVE POTENTIAL, TO THE ACTUAL WHEEL LOAD. CERTAIN CONSTANTS ARE USED TO FACILITATE CONVERSION OF THE VARIOUS WHEEL LOADS OCCURRING IN MIXED TRAFFIC TO EQUIVALENT 5,000- POUND WHEEL LOADS. THESE CONSTANTS, TERMED TRUCK OR EQUIVALENT WHEEL LOAD CONSTANTS, ARE DERIVED FROM STATISTICAL DISTRIBUTIONS OF TRUCK AXLE LOADS AND ARE CALCULATED SEPARATELY FOR EACH GROUP OF TRUCKS CATEGORIZED ACCORDING TO NUMBER OF AXLES. THIS REPORT PRESENTS THE RESULTS OF AN EXAMINATION OF THE NEED FOR SEPARATE SETS OF TRUCK CONSTANTS FOR STATE HIGHWAYS AND FOR CITY STREETS AND COUNTY ROADS. THE DISTRIBUTION OF WHEEL LOADS ON CERTAIN CITY STREETS AND COUNTY ROADS IS EVALUATED AND COMPARED WITH WHEEL LOADS FOUND ON STATE HIGHWAYS. DATA FOR THE LOCAL TRAFFIC CONDITIONS WERE OBTAINED FROM 25 LOADOMETER LOCATIONS WHICH COVER COMMERCIAL, FARM-TO-MARKET, CONNECTOR AND COLLECTOR STREETS AND ROADS. LOADOMETER STATIONS WERE OPERATED BETWEEN THE HOURS OF 7 TO 12 A.M. AND 1 TO 4 P.M. THE STUDY DEVELOPED THE FOLLOWING INFORMATION' /1/ THE TRUCK CONSTANTS DETERMINED FOR LOCAL ROAD TRAFFIC WERE FOUND TO BE APPRECIABLY LESS THAN THOSE THAT HAD BEEN DEVELOPED FOR STATE HIGHWAY TRAFFIC, /2/ THE TRAFFIC INDEX FOR TYPICAL LOCAL ROAD TRAFFIC WAS REDUCED 7% BY USING THE TRUCK CONSTANTS DETERMINED IN THIS STUDY, AND /3/ APPLICATION OF THE REDUCED TRAFFIC INDEX TO TYPICAL LOCAL ROAD DESIGN SITUATIONS RESULTED IN THICKNESS REDUCTIONS THAT VARIED FROM 6 TO 11% FOR THE DIFFERENT LAYERS OF THE FLEXIBLE PAVEMENT SYSTEM. /BPR/

  • Supplemental Notes:
    • Hpr-1/4/, D-4-29 /STATE/
  • Corporate Authors:

    California Division of Highways

    Bridge Department
    Sacramento, CA  USA  05914
  • Authors:
    • Shirley, E
    • Anderson, D
  • Publication Date: 1966-6

Subject/Index Terms

Filing Info

  • Accession Number: 00205342
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS
  • Created Date: Oct 1 1994 12:00AM