by Cindy Smith, Assistant State Research Engineer, Mississippi DOT
and Dr. Feng Wang, Associate Professor, Jackson State University
The Mississippi Department of Transportation (MDOT) began using pavement warranties in 2000 and has awarded approximately 21 warranty projects since then. Four of these are still under a warranty period. Most (18) were asphalt, and 3 were jointed concrete pavements. Jackson State University (Wang, Qi, El-Gendy, et al.) did a previous research study, published in 2012, on MDOT’s warranty program. Among the findings of this study were the following:
- Potential benefits of implementing pavement warranty include decreased construction oversight, enhanced pavement quality, flexibility in pavement type and material selection, and the potential for the industry to use its knowledge more productively, primarily because of the shift from a passive to an active attitude toward quality.
- The analytical results show that the performance of the warranty pavements is significantly better than that of the 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.
- While MDOT’s warranty program helps pavement performance, 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.
This report can be found at the following link:
With this recommendation in mind, MDOT is contracting again with Jackson State University to refine the thresholds. The following are reasons for this study:
- MDOT uses deduct points calculated from distress quantities and severities, rather than the distress quantities and severities themselves or distress densities. These deduct points were originally developed as part of a composite index calculation in network-level collection.
- Up until the 2010 biannual pavement condition survey, MDOT analyzed distresses on two 500-ft samples per mile. Since 2010, MDOT has had the data collection vendors collect the entire lane using 100% automated collection methods. However, MDOT continued to use manual rating and sampling on the in-house-collected warranty projects since this was better suited to project-level rating and since most warranty contracts were in place prior to 2010.
- Most states with warranty projects use distress thresholds rather than deduct points. The use of thresholds or densities would be easier and more straightforward for contractors and MDOT than deduct points.
- Currently, roughness is not used for warranty performance standards. In recent years, MDOT has begun using Mean Roughness Index (MRI) for construction acceptance. We would like to investigate the possibility of using MRI in warranty projects as well.
The JSU/MDOT study will take two years and will include tasks of developing statistical models and new distress thresholds, as well as validation and documentation of these. Both MDOT and JSU look forward to refining, streamlining, and updating Mississippi’s warranty project process.
for more information, please contact Cindy Smith at cjsmith@mdot.ms.gov