Skip-Lot Acceptance Sampling Plans for Highway Construction and Materials

Abstract

Current acceptance sampling plans for highway construction and materials require the sampling and testing of every individual lot (i.e., 100% of the lots are inspected). This approach is appropriate if the contractor is erratic. However, if the contractor is fairly consistent, skip-lot sampling suggests that only a fraction of the lots need to be tested. This paper presents an algorithm for developing skip-lot sampling plans for highway construction and materials acceptance. A skip-lot acceptance sampling plan has been developed and compared with AASHTO’s lot-by-lot acceptance plan. The analysis shows that skip-lot sampling reduces the amount of acceptance sampling and testing when the contractor has a history of delivering high-quality product. Rather than simply testing every lot for every acceptance quality characteristic, highway agencies can use skip-lot sampling to develop knowledge-based acceptance plans.