PROCEDURES FOR ESTIMATING THE TOTAL LOAD EXPERIENCE OF A HIGHWAY AS CONTRIBUTED BY CARGO VEHICLES

THE PRIMARY PURPOSE WAS TO DEVELOP AND TEST PROCEDURES FOR MAKING ACCURATE ESTIMATES OF THE TOTAL LOAD IN TERMS OF 18-KIP AXLE EQUIVALENTS THAT A HIGHWAY WILL EXPERIENCE FROM CARGO VEHICLES OVER ITS DESIGN PERIOD. SUCH AN ENDEAVOR INVOLVED AN EVALUATION OF VEHICLE WEIGHT AND CLASSIFICATION COUNT DATA PREVIOUSLY COLLECTED AT EXISTING LOADOMETER AND MANUAL COUNT STATIONS. TWO PROCEDURES WERE USED TO MAKE ESTIMATES OF THE ACTUAL TOTAL 18-KIP AXLE EQUIVALENTS GENERATED BY CARGO VEHICLES WEIGHTED AT EACH OF THE 21 CONVENTIONAL STATIC WEIGHT LOADOMETER STATIONS DURING 1967 AND 1964-68. ONE PROCEDURE USED MULTIPLE REGRESSION MODELS IN WHICH THE "DUMMY" VARIABLES REPRESENT VARIOUS CHARACTERISTICS OF THE VEHICLES WEIGHTED. THE ACTS OF VARIABLES ENTERED INTO THE MODELS INCLUDED VEHICLE TYPE, BODY TYPE, FUEL TYPE, TIME OF WEIGHING (NIGHT, DAY OF WEEK, SUMMER AND YEAR) AND LOAD STATUS. THE OTHER PROCEDURE USED AXLE WEIGHT FREQUENCY DISTRIBUTION SETS COMPOSED OF ONE-KIP (1000 POUND) WEIGHT CLASSES, 40 FOR SINGLE AXLE AND 50 FOR TANDEM AXLES. THE FREQUENCY SETS DEVELOPED WERE AS FOLLOWS: (1) COMBINED STATIONS, (2) COMBINED STATIONS BY VEHICLE TYPE, (3) COMBINED STATIONS BY FUEL TYPE, (4) SAMPLE SIZES. COMBINING STATIONS AND/OR YEARS MADE BY HIGHWAY AND SYSTEM VEHICLE TYPE AND, (6) COMBINED STATIONS BY HIGHWAY SYSTEM. FREQUENCY SET 5 PROVED TO BE THE MOST ACCURATE, EVEN MORE ACCURATE THAN THE REGRESSION MODELS. THESE WERE TESTED FOR REPRESENTATIVENESS OF THE VEHICLE TRAFFIC AND RELIABILITY OF STATISTICS. ALSO THE WEIGHING AND COUNTING SCHEDULES AND SAMPLE SIZES WERE EVALUATED. CONVENTIONAL LOADOMETER STATION DATA WERE COMPARED WITH LIMITED WEIGH-IN-MOTION STATION DATA. THE WEIGHT AND COUNT SAMPLE SIZE REQUIREMENTS WERE ESTABLISHED THROUGH THE USE OF A STATISTICAL FORMULA WHICH UTILIZES SAMPLE AVERAGES AND VARIANCES WITH 10 PERCENT ERROR AND 95 PERCENT PROBABILITY LEVEL CRITERIA. IT WAS FOUND THAT A CONSIDERABLE AMOUNT OF STATION TO STATION VARIATION IN THE SAMPLE STATISTICS WAS DUE TO DIFFERENCES IN THE WEIGHING OR COUNTING SCHEDULES AND SAMPLE IZES. COMBINING STATIONS AND/OR YEARS MADE THE DATA MORE REPRESENTATIVE AND INCREASED THE RELIABILITY OF THE SAMPLE STATISTICS. /AUTHOR/

  • Corporate Authors:

    Texas Transportation Institute

    Texas A&M University System, 1600 E Lamar Boulevard
    Arlington, TX  USA  76011

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  USA  20590

    Texas State Department of Highways & Public Transp

    11th and Brazos Streets
    Austin, TX  USA  78701
  • Authors:
    • Buffington, J L
    • Schafer, D L
    • Adkins, W C
  • Publication Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 00208006
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: Study No 131
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Jan 31 1972 12:00AM