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Publication Number: FHWA-HRT-12-011
Date: March 2012
Printable Version (.pdf, 1.1 mb)
A new Tech Brief released by the Federal Highway Administration (FHWA) provides guidance State transportation agencies can use in conducting an Independent Assurance (IA) Program to evaluate the sampling and testing procedures they use in their materials and quality assurance (QA) program.
As required by 23 Code of Federal Regulations (C.F.R.) 637 for projects on the National Highway System, an IA Program ensures that materials sampling and testing are performed correctly and that the testing equipment used is operating correctly and remains calibrated. To conduct the IA Program, a separate and distinct schedule of sampling, testing, and observation must be maintained by personnel other than project personnel.
Independent Assurance Programs (Pub. No. FHWA-HIF-12-001) discusses best practices for meeting the C.F.R. requirements, including choosing a systems versus project approach. While a project approach covers all projects, a systems approach covers all QA testers. Also addressed is the frequency of IA testing, which may be based on the testing frequency performed for the project’s regular QA program or on a specified time interval for a project. Alternatively, a systems approach may be used to base the IA frequency on the number of times that all personnel who perform testing used in the acceptance decision will have to be reviewed during a year. IA evaluators would then review the work of these personnel at specified intervals. A mix of both of these approaches can also be used. The regulations require States that use the systems approach to submit an annual report to their FHWA division office.
Test equipment can be evaluated by using calibration checks, split samples, or proficiency samples, while testing lab personnel can be evaluated through observations and either split samples or proficiency samples. The typical approach for performing IA is to check equipment and personnel at the same time. IA evaluators visit a job site to observe the sampling and testing being performed and to also test a split sample on site with equipment brought by the testers, or to take the sample to a laboratory for testing. If the split samples do not compare, then further analysis is required to determine if the source of the error is in the procedures or equipment.
Other States perform testing on three-way split samples. Using this approach, one split is tested by project personnel, one by the contractor personnel, and one by the IA personnel. This is typically done at the beginning of production to ensure that all testing personnel and equipment are functioning correctly. The Tech Brief also discusses the way proficiency samples can be used in an IA Program.
As the Tech Brief notes, IA Programs must compare results and detect deficiencies in State or contractor testing procedures in a timely manner. Deviations from established tolerances will require an audit of the respective sampling and testing procedures, as well as the equipment used. The Tech Brief discusses how to establish comparison tolerances and how often to reevaluate these decisions. While some States evaluate their tolerance levels every year, at a minimum the tolerances should be evaluated every 5 years.
To download the Tech Brief, visit www.fhwa.dot.gov/pavement/materials/hif12001.pdf. To view the C.F.R. regulation, visit www.access.gpo.gov/nara/cfr/waisidx_03/23cfr637_03.html. For a list of frequently asked questions on the quality assurance regulation, visit www.fhwa.dot.gov/pavement/materials/qanda637.cfm. For more information on materials quality assurance, contact Michael Rafalowski at FHWA, 202-366-1571 (email: firstname.lastname@example.org), or Dennis Dvorak at the FHWA Resource Center, 708-283-3542 (email: email@example.com).
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