The LTPP SPS-2 experiment (Strategic Study of Structural Factors for Rigid Pavements) is the most comprehensive ongoing concrete research effort in the nation. It represents the largest research effort undertaken since the AASHO Road Test and represents a national investment on the order of $15 to $20 million dollars for the construction, sampling and testing, monitoring, and analysis of the concrete pavements. Thirteen of these sites still exist and are continuing to be monitored and evaluated. Beginning in 1992, fourteen states constructed SPS-2 experiments. The current projects range in age between 12 and 20 years. Many of these sites have formed the basis for the calibration of the MEPDG. These sites are unique in that they represent the only national comprehensive concrete experiment that has sampled and tested the materials and monitored the pavement performance throughout the construction and service life of the roadway. Each site has received extensive materials characterization, performance monitoring and environmental and traffic data collection. True cradle to grave analysis is possible at these locations. Additionally, these sites have the highest quality traffic data available for any research effort. Due to the age of the existing SPS-2 projects, it is now time to develop a second experiment, based upon the first, which determines the most effective concrete preservation strategies for extending the service life of these pavements. It is paramount that as these pavements begin to deteriorate, that the proper intervention time and prevention strategy be determined and implemented. As indicated in the SHRP-2 R26 final report, most concrete preservation strategy life extensions have not been adequately defined. The Washington DOT will serve as the lead state for the execution of the pooled fund project described in this problem statement. A Technical Advisory Committee (TAC) will be comprised of representatives from the funding agencies/entities of the pooled fund. The TAC will review and approve the pooled fund activities and budget. TAC members will potentially include state DOTs, industry, academia, FHWA, and FHWA LTPP contractors. Deliverables will be prioritized by the TAC as funding is available.

This pooled fund effort is established to develop a second tier experiment based upon the existing SPS-2 experiment. The objective is to define the proper intervention timing and strategy selections enabling more effective infrastructure management and pavement life extension. In addition, this effort should develop tools for determining strategy selection and pavement life extension for incorporation into pavement and maintenance management systems.

Since the existing SPS-2 projects already have extensive on-going data collection taking place, field data collection costs will be substantially reduced for this effort. As such, considerable leveraging of existing data and future collected data can occur. The attached documents indicate 17 different opportunities that could be undertaken in this pooled fund project should the project funding and development allow. The following minimum activities are recommended, but can be modified by the TAC once formed: 1. Conduct a virtual tour of the existing 13 SPS-2 experiments across the country. Define the lessons learned and experience to date, both from a design assessment and a preservation assessment. If actual field scans are conducted, coordinate showcases with local industries/associations to conduct best practices seminars for preservation strategies. 2. Development of a planned SPS-2 Pavement Preservation Experiment. This will require evaluating the available sites and strategies, and determining what can be accomplished and where, in the context of preservation. Since the original experiment was not a full-factorial experiment, limitations to the extension of the experiment may need to be defined and approaches for overcoming the shortcomings identified. 3. Determination of the pavement life extension resulting from each of the selected pavement preservation strategies. One aspect of the SHRP2 R26 effort was that actual life extension data for each of preservation strategies was almost non-existent. For effective pavement management, it is necessary to establish actual life extension as a result of the application of a given treatment. This needs to be established quantitatively not qualitatively. 4. Defining performance measures and intervention periods. There is a need to define the proper parameters for assessing pavement performance and the intervention timing. A recent survey by the FHWA Pavement Preservation ETG indicated that few, if any, states use the same performance metrics for their pavement management systems. The best metrics for evaluating performance and deciding upon the timing for preservation intervention needs to be established, based on actual data. 5. Collaborate with the SHRP2 R26 implementation to leverage the resources of both projects. The LTPP SPS-2 project provides the most robust data set for implementing the results of the R26 effort. Every effort should be made to coordinate these efforts to prevent duplication, and to ensure more effective and complete research. The LTPP effort is a long-term on-going effort that can continue to produce results far into the future. 6. Comparison of remaining capacity to remaining service life. Traditionally, concrete pavements have oftentimes exceeded their design traffic loadings by many times. As such, it has been easy for agencies to ignore actual preservation and to just use the “repair when broken approach”. With the advent of the MEPDG it is now possible to establish the performance curves over time. This enables an agency to compare predicted performance to actual performance from the very beginning. That is, if the pavement is performing as planned, the design and construction are adequate. If not, an investigation is warranted to improve one or both of the processes. Similarly, the remaining capacity should be determined based on the traffic that has occurred, and then compared to the predicted performance (at design) and the remaining service life established through conventional procedures. 7. Changes in Material Properties Over Time. One aspect of concrete pavement is that it continues to increase in strength with time in many cases. This increase has been reported to achieve 1.4 times the 28 day compressive strength. This strength gain needs to be documented and used in the strategy selection process, and ultimately, in the pavement life extension process.

The estimated project duration is for three years, with a future option to extend if deemed necessary and pending funding availability. We propose that State DOTs, FHWA, other agencies, and industry may participate in the pooled fund. We are looking for a minimum contribution of $20,000 per state each year (a minimum of 5 states) = $100,000/year. The pooled fund will pay the travel costs for one representative of the participating agency, or their representative, to attend the face-to-face TAC meetings. Summary of Requirements for Project Sponsors •Financial support. •Meeting participation on conference/web calls and in the annual face-to-face meeting. •Active collaboration/partnering with all TAC members. •Championing, within their state/organizations, the deliverables from the pooled fund.