TWO QUARTER-CAR MODELS FOR DEFINING ROAD ROUGHNESS: IRI AND HRI

There is now a movement in the United States toward standardizing road roughness measurements by using a scale called the International Roughness Index (IRI). The IRI was defined by the World Bank (based on earlier work performed for the NCHRP) and is required by the Federal Highway Administration (FHWA) for the roughness database of the Highway Performance Monitoring System (HPMS). The IRI is defined as a roughness description for a single wheeltrack profile, obtained by using a quarter-car model with certain specified parameter values. A related roughness measure is obtained by using both wheeltrack profiles as inputs to the same computer algorithm used for the IRI. This analysis is mathematically equivalent to a half-car model and produces a roughness measure called the half-car roughness index (HRI). There is currently a mixture of IRI and HRI data being measured in the United States. The two analytic methods are so similar in concept that many practitioners are not aware of the difference between them. As a result, there has been occasional confusion and error when data are reported. The purpose of this paper is to identify and discuss the differences and similarities between IRI and HRI. The paper also summarizes technology (automated profiling systems) used to measure IRI and HRI.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/trr/1989/1215/1215-018.pdf
• Record URL:
  https://scholar.google.com/scholar_lookup?title=TWO+QUARTER-CAR+MODELS+FOR+DEFINING+ROAD+ROUGHNESS%3A+IRI+AND+HRI&author=M.+Sayers&publication_year=1989
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0309048192
• Supplemental Notes:
  • This paper appears in Transportation Research Record No. 1215, Pavement Management and Rehabilitation. 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
• Authors:
  • Sayers, Michael W
• Publication Date: 1989

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 165-172
• Monograph Title: Pavement management and rehabilitation
• Serial:
  • Transportation Research Record
  • Issue Number: 1215
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Measurement; Roughness; Simulation; Standardization
• Identifier Terms: International Roughness Index
• Old TRIS Terms: Automated profiling systems
• Subject Areas: Highways; Pavements; I23: Properties of Road Surfaces;

Filing Info

• Accession Number: 00494461
• Record Type: Publication
• ISBN: 0309048192
• Files: TRIS, TRB, ATRI
• Created Date: May 31 1990 12:00AM