Optimal Procedures for Quality Assurance Specifications
"Optimal Procedures for Quality Assurance Specifications," Publication No. FHWA-RD-02-095 is intended as a guide that a highway agency can use when developing new, or modifying existing, acceptance plans and quality assurance (QA) specifications. It is intended to provide necessary instruction and illustrative examples to lead the agency through the entire process of acceptance plan development, including:
- Setting up the initial data collection/experimentation to determine typical parameters of current construction.
- Establishing the desired level of quality to be specified.
- Designing the actual acceptance plan itself, including selecting quality characteristics, statistical quality measure, buyer's and seller's risks, lot size, number of samples (sample size), specification and/or acceptance limits, and payment-adjustment provisions.
- Monitoring how the acceptance plan is performing.
- Making necessary adjustments.
The acceptance plans described in this manual are based on QA principles intended to provide the "...confidence that a product or facility will perform satisfactorily in service." To achieve this end, the acceptance plans must be realistic, must be fair to both the contractor and agency, and must be statistically accurate. The purpose of this manual is to explain how this can be done, through discussion and with examples where appropriate.
The information in this manual is based on a pooled-fund study conducted under State Planning and Research Pooled-Fund number 2(199) administered by the Federal Highway Administration (FHWA). The FHWA Contracting Officer's Technical Representative for this study was Peter A. Kopac. The material presented herein is based on review of the literature, the input of a panel comprised of a representative from each of the States in the pooled fund, numerous statistical analyses conducted for the project, and the past experiences of the authors.