The National Academies

NCHRP Synthesis 20-05/Topic 48-12 [Active (Synthesis)]

Inertial Profiler Certification for IRI Measurements
[ NCHRP 20-05 (Synthesis of Information Related to Highway Practices) ]

  Project Data
Funds: $45,000
Authorization to Begin Work: 5/9/2016 -- estimated
Staff Responsibility: Crawford Jencks
Research Agency: SME
Principal Investigator: Rohan Perera
Effective Date: 9/21/2016
Fiscal Year: 2016

Final Scope

Inertial profilers are primarily used for collecting repeatable and reproducible road profiles. These road profiles are then analyzed to calculate a smoothness or ride quality index, the most common of which is the International Roughness Index (IRI). The IRI is often used as a smoothness measure for acceptance of construction projects. Inertial profilers are also used to measure IRI at the network level. The IRI is a performance measure that state departments of transportation have to report to the Federal Highway Administration (FHWA) as a part of HPMS/MAP-21 and FAST Act requirements.

The certification of the inertial profiler is extremely important to ensure accurate data is collected both for smoothness specifications at the project level and also for MAP-21 and FAST Act requirements that the states provide accurate and consistent IRI data.

The study will perform a thorough literature review (including international) and survey of all state DOTs, and equipment vendors to determine the state of practice of certification of inertial profiler at the national and international levels. There is a need to locate the DOT offices that conduct both network and project level inertial profiles. The contact list for the TPF5063 pool fund study and the state HPMS coordinators (FHWA will provide) will be used to identify contacts in the state DOTs. Other sources will be AASHTO Subcommittee on Construction and Subcommittee on Materials.

Follow-up interviews will be conducted with selected states having established programs that are fully operational.

Information will be gathered on at least the following topics for both network and project level-

• What is the reference device used for certification of inertial profilers.
• Surface material types, ranges of roughness, and textures used in the certification process.
• The procedure for developing reference profiles.
• The test procedure used for certification.
• The criteria used for certification of equipment.
• The criteria used for certification of operators.
• Procedures for handling equipment or operators that cannot pass certification.
• Certification reciprocity among states.
• The costs of certification for equipment and operators.
• Maintenance and operation of certification facility.
• Management of certification facility.
• Site geometry.
• Duration of validity of the certification for both equipment and operators.
• Tests/procedures/processes to monitor the inertial profiler equipment operation and validity/quality of collected and reported network data subsequent to certification.
• Certification documentation.
• Procedures for construction smoothness quality assurance, referee and /audits.

The study will also note gaps in current knowledge and practice, and research needs.

Information Sources:

• ASTM Certification Standard E950
• Helen Viner (TRRL, England)
• Richard Wix (ARRB, Australia
• TPF5063 pool fund study (http://www.pooledfund.org/Details/Study/280)
• TPF5354 pool fund study
• Vendors- RPUG.org website

TRB Staff 
Crawford Jencks

Phone: 202-334-3245

Topic Panel
Srikanth Balasubramanian, California DOT
James Howard Greene, Jr., Florida DOT
Narinder Kohli, New Jersey DOT
Hosin Lee, Public Policy Center
Magdy Y. Mikhail, Texas DOT
Brian L. Schleppi, Ohio DOT
Amy L. Simpson, AMEC Foster Wheeler Environment & Infrastructure, Inc.
Robert Orthmeyer, Federal Highway Administration
Larry Wiser, Federal Highway Administration
James W. Bryant, Jr., Transportation Research Board


Meeting Dates
First Panel:  September 21, 2016, Washington, DC
Teleconference with Consultant: October 7, 2016, 1:30 p.m., EST
Second Panel: June 13, 2017, Woods Hole, MA

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