Evaluation Of Mdots Distress Thresholds For Maintained Pavement Projects PDF Download

As an alternative to traditional contracting, pavement warranty has been adopted in Mississippi since 2000, aimed to enhance pavement performance and protect the investment in pavement construction. Currently, a manual distress survey method and the associated deduct point-based pavement condition rating approach are employed to monitor the performance of warranty pavements (maintained projects). The main objective of this study is to evaluate the appropriateness of using the current deduct points distress thresholds to monitor the performance of the maintained projects in Mississippi. In the study, a comprehensive literature review and online survey were conducted to review the recent state of practice of pavement warranty in North America. The analytical section of the study employed pavement distress and riding quality data collected form warranty pavements and the corresponding data of non-warranty pavements stored in MDOT's Pavement Management System (PMS) for the statistical analysis. Using raw data, converted deduct points, and composite index as performance indicators, basic statistics were developed to investigate the distribution of performance indicators at various service times and the corresponding percentiles associated with the existing threshold values. In addition, pairwise comparisons were conducted to examine the evolvement of distress over time for warranted and non-warranted pavements. Further, two sample t-tests were performed to compare the performance of warranted and non-warranted pavements at the same service time. The survey study has shown that most other pavement warranty programs in other states use direct measurements of pavement distresses or densities of pavement distresses for their distress indicators and thresholds while the pavement warranty program at MDOT employs deduct points based distress thresholds which are quantities converted from measurements of pavement distresses. The analytical results show that the performance of warranty pavements is significantly better than that of non-warranty pavements at the same service time level, and warranty pavements can maintain at high service levels for a longer time than non-warranty pavements. The pavement warranty program adopted by MDOT has improved pavement performance, and is effective in practice. However, the current distress thresholds adopted by MDOT are inconsistent with regard to the various corresponding percentile levels for different distress types at a same service time, and the different increase rates of the percentile level for different distress types over service time. It is suggested that direct measurements of pavement distresses or distress densities be used as distress thresholds, and consistent threshold levels be implemented for all distress types.