A Case Study in Establishing Quality Assurance Limits for Automated Pavement Distress Data in North Carolina

The North Carolina Department of Transportation (NCDOT) began collecting automated pavement distress data on a state-wide basis in 2012. Concurrently, they contracted the quality assurance reviews of the reported pavement distress to an independent source. This paper discusses the means and methods utilized by NCDOT and the quality assurance contractor to develop statistically valid quality assurance limits, which are also meaningful in terms of pavement management decision-making impacts, for the collected and processed asphalt pavement distress data. The paper describes the strategic selection of control sections to include a range and mix of the distresses with impact in the current decision trees, the data collection on the control sections, the rating methodology, and the rater pools and preparation to develop predicted limits for the control of the data. The paper discusses the consideration of multiple control indices, and the need to also reflect a range of values for those aggregate indices for multiple distresses, and presents the statistical analysis from the asphalt concrete control sites.