Development of a Methodology to Determine the Appropriate Minimum Testing Frequencies for the Construction and Maintenance of Highway Infrastructure

摘要

The objective of this research is to develop a methodology for determining the optimal sample size and appropriate testing frequencies for construction materials on the basis of a statistically sound approach. By conducting a review of the state-of-the-art in testing procedures and frequencies used by various transportation departments and other agencies, a formula is established to define the relationship between required sample size and the parameters involved. Statistically, the optimal sample sizes or appropriate testing frequencies are primary based on four issues: The variability of the quality characteristics being measured, the risks that a state DOT or a contractor is willing to take, the tolerable errors each is willing to accept, and the cost of the testing to be performed. A sensitivity analysis is conducted to show how sensitive the sample size is to the change of material variability, confidence level, and tolerable error. Using the data collected from TxDOT districts and the methodology developed under the project, the frequencies for certain TxDOT testings are developed and compared to the current TxDOT Testing Schedule. Recommendations are also made to implement the research results.