BITUMINOUS CONSTRUCTION

THE HIGHWAY INDUSTRY IS RELUCTANT TO ABANDON TRADITIONAL METHODS AND SPECIFICATIONS AND ADOPT STATISTICALLY DERIVED TOLERANCES, EVEN THOUGH THE NEW LARGER TOLERANCES ARE DEMONSTRABLY SOUND. FOUR STEPS ARE NECESSARY TO IMPLEMENT STATISTICAL SPECIFICATIONS: (1) ESTABLISHMENT OF A REALISTIC VARIABILITY; (2) USE OF THE VARIABILITY TO ESTABLISH REALISTIC TOLERANCES; (3) SIMULATION OF THE NEW SPECIFICATION; AND (4) USE OF THE NEW SPECIFICATION AS THE BASIS OF ACCEPTANCE IN A CONTRACT. ONLY FOUR STATES HAVE REACHED THE LAST STEP. THE TYPICAL COMPONENTS OF STATISTICAL SPECIFICATIONS ARE: LOT SIZE, SAMPLE, NUMBER, ACCEPTANCE OF CENTRAL TENDENCY, ACCEPTANCE OF VARIABILITY, OTHER ACCEPTANCE CRITERIA (PERCENT DEFECTIVE PRODUCT QUALITY INDEX, SEQUENTIAL ANALYSIS LIMITS), ADJUSTMENT OF BID PRICE, CONTROL CHARTS, AND RETESTING AND REFEREE PROCEDURES. BECAUSE OF THEIR CLARITY AND DEFENSIBILITY, STATISTICAL SPECIFICATIONS SOLVE MANY OF THE PROBLEMS CAUSED BY INDEFINITE AND ARBITRARY SPECIFICATIONS. HOWEVER, THERE IS A LACK OF STATISTICAL TRAINING AMONG ENGINEERS, WHICH MUST BE REMEDIED BEFORE STATISTICAL SPECIFICATIONS CAN BE IMPLEMENTED.

• Record URL:
  https://onlinepubs.trb.org/Onlinepubs/sr/sr118/118-002.pdf
• 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.
• Corporate Authors:

  Highway Research Board (HRB)

  Washington, DC   
• Authors:
  • Hughes, C S
• Publication Date: 1971

Media Info

• Media Type: Digital/other
• Features: Tables;
• Pagination: pp 3-6
• Monograph Title: Quality assurance and acceptance procedures
• Serial:
  • Highway Research Board Special Report
  • Issue Number: 118
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Acceptance; Bituminous construction; Engineering tolerance; Quality control; Specifications; Standards; Statistical analysis; Statistical quality control; Variables
• Old TRIS Terms: Tolerances
• Subject Areas: Data and Information Technology; Highways; Materials;

Filing Info

• Accession Number: 00211601
• Record Type: Publication
• Files: TRIS, TRB, ATRI
• Created Date: Jul 25 1971 12:00AM