Using Existing Pavement in Place and Achieving Long Life (2014)

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7C h a p t e r 2 Introduction This chapter describes the study’s research approach. The primary research was to confirm that long-life pavements could be designed and constructed using the existing pavements as part of the structure. To do this, two major phases were conducted. Phase 1 began the study with a thorough literature review documenting the potential long- life approaches using existing pavements. This included a comprehensive evaluation of state highway agency (SHA) project records and international documentation. Detailed analyses of pavement performance, including information from the Long-Term Pavement Performance (LTPP) data- base, were used to confirm the approaches that could pro- vide 50 years of service life. During Phase 2, additional information became available and it was used to refine the findings from Phase 1, as well as to develop the guidelines and tools delivered as part of the project. SHRP 2 defined long-lived pavements as those that last 50 years or longer without requiring major structural reha- bilitation or reconstruction. This definition was the primary criterion that resulted in the findings and products associated with this study. phased research approach This project’s research started with an extensive discovery process in Phase 1, consisting of agency surveys, literature reviews, and specific queries of individuals throughout the world. The information gained in Phase 1 was used to develop the long-life guidance in Phase 2. Additionally, more detailed information was collected during site visits with several agen- cies in Phase 2. Information gathered in both Phase 1 and Phase 2 was used to produce the research findings and products described in Chapter 3. Phase 1 Structure The Phase 1 discovery process consisted of the following individual tasks: • Literature review; • National and international survey of practice; • Review of practices in 15 states; • Analysis of LTPP data to confirm long-life performance of different approaches; and • Mechanistic-Empirical Pavement Design Guide (MEPDG) and PerRoad runs to predict long-life performance. A literature search for information on highway renewal using existing pavements in place was conducted. The find- ings from the literature review are discussed in Chapter 3 with details in Appendix A. Literature Review The literature review served three purposes. First, it allowed the team to refine the definition of long-life pavements, as well as typical criteria that are currently used by the industry to differentiate between conventional and long-life pave- ments. Second, it provided a means to develop a complete list of viable approaches that have been used by SHAs and show promise for meeting the established long-life criteria. Third, the data from the literature provided insight into the design, features, and configurations of each alternative. The following list shows the strategies that were obtained from the literature review: • Asphalt concrete (AC) over AC renewal methods: 44 AC over existing AC pavement, 44 AC over rubblized AC pavement, 44 AC over reclaimed AC (recycling), and 44 Lane additions. Research Approach

8• AC over portland cement concrete (PCC) renewal methods: 44 AC over existing continuously reinforced concrete pavements, 44 AC over crack and seat jointed plain concrete pavements (JPCPs), 44 AC over rubblized JPCP, and 44 Lane replacement (inlay) and lane additions. • PCC over PCC-renewal methods: 44 Unbonded PCC overlay of PCC pavement, 44 Bonded PCC overlay of PCC pavement, and 44 Lane replacement (inlay) and lane additions. • PCC over AC renewal methods: 44 Unbonded PCC overlay of AC pavements, 44 Bonded PCC overlay of AC pavements, and 44 Lane replacement (inlay) and lane addition. These approaches were analyzed as part of Phase 1, and the findings are described in Chapter 3. Survey of Practice A survey of national and international practices was part of the Phase 1 effort. Questionnaires were sent to each of the SHAs, the Federal Highway Administration (FHWA), and industry. These were followed by a series of e-mails and phone calls to learn more about individual projects. In some cases, the team visited SHAs to obtain project-level infor- mation. The agencies surveyed are listed below (those that responded are in bold): • National Asphalt Pavement Association; • American Concrete Pavement Association; • SHAs and FHWA division offices of Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Puerto Rico, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming; • Antigo Construction, Carlo Construction, Duit Con- struction; and • Government and industry contacts in Argentina, Aus- tralia, Belgium, Canada (British Columbia, Ontario, and Québec), Chile, Colombia, Germany, Italy, Japan, the Netherlands, South Africa, Sweden, Taiwan, and the United Kingdom. To obtain more detailed information, several agencies and individuals were contacted. The following individuals provided information on the approaches that had been used by their agency and how they were performing: • Colorado (Steve Olson); • Florida (Bruce Dietrich); • Georgia (Georgene Geary); • Indiana (Dave Kumar); • Iowa (Chris Brake); • Michigan (Michael Eacker); • New York (Wes Yang); • North Carolina (Judith Corley-Lay); • Ohio (Roger Green); • Oklahoma (Jeff Dean); • Ontario (Tom Kazmierowski); • Oregon (John Coplantz); • South Carolina (Andrew Johnson); • Texas (Magdy Mikhail); and • Washington (Jeff Uhlmeyer). These contacts provided access to the available documenta- tion. In several cases, they provided project-specific informa- tion including design documents, copies of plan sheets, date of construction, and current condition. A sample of this infor- mation is illustrated in the plan section (Figure 2.1) provided by the Oregon DOT. LTPP Data and MEPDG Analysis Neither the literature review nor the survey of current practices confirmed the long-life performance of the approaches being considered. Although there was information on the long-life aspects of new pavements, there was none on the approaches for using existing pavements in place. To provide more infor- mation on service life, both the specific pavement study (SPS) and the general pavement study (GPS) sections in the LTPP database were investigated. There were several SPS and GPS experiments that specifically included some of the approaches being considered. For the flexible pavements sections, the following LTPP experiments were considered: • GPS-6A and GPS-6B (AC overlay over AC pavement); • GPS-7A and GPS-7B (AC overlay over PCC); • SPS-5 (AC overlay of AC pavement); and • SPS-6 (rehabilitation of jointed PCC pavement). For rigid pavement sections, they were the following: • GPS-9 (unbonded PCC overlays of PCC pavement); and • SPS-7 (bonded PCC overlays on PCC pavements). In most cases, the LTPP data indicated general trends but the performance periods were not long enough to show which approaches would provide the long-life service required for

9the study. To provide additional insight, specific test sites for both flexible and rigid pavements were analyzed using the MEPDG. At the time of the analysis, the MEPDG did not include limiting strain criteria, so PerRoad was also used (which does provide for selection of limiting strain criteria). Features that would produce long-life performance and those that might limit long-life performance were consid- ered. The findings are described in Chapter 3, and the detailed analysis of both the LTPP data and the MEPDG is included in Appendix B. Phase 2 Structure Phase 2 had several activities that were continuations from Phase 1. The critical activities were the following: • Develop guidelines based on findings from Phase 1. • Work with seven agencies to develop and test the guide- lines, using 44 Agency visits; and 44 Test cases. • Develop an interactive program to facilitate the use of the guidelines and provide a platform for the information needed to produce long-life pavements. • Develop the information needed to produce long-life pave- ments, which is contained in the following documents: 44 Guide, Chapter 1—Project Assessment Manual; 44 Guide, Chapter 2—Flexible Pavement Best Practices; 44 Guide, Chapter 3—Rigid Pavement Best Practices; 44 Guide, Chapter 4—Guide Specifications; 44 Guide, Chapter 5—Life-Cycle Cost Analysis; and 44 Guide, Chapter 6—Emerging Pavement Technology. • Conduct two regional workshops to get additional feedback on the guidelines. Guidelines were developed initially in outline form and then converted to decision tables, which made them easier to use. The development of the guidelines and their refinements based on agency reviews and comments is described in this report’s Chapter 3. Agency Visits Seven agencies were visited during the development of guidelines. Those agencies and the primary contacts were the following: • Illinois Tollway Authority (Steven Gullien); • Michigan DOT (Michael Eacker); • Minnesota DOT (Shongtao Dai); • Missouri DOT (John Donahue, William Stone); • Texas DOT (Magdy Mikhail); • Virginia DOT (Trenton Clark, Alex Teklu); and • Washington State DOT (Jeff Uhlmeyer). In the initial set of meetings, the team met with the agency to introduce the project and obtain appropriate details. The team asked the agencies to identify specific projects where they had used the previously identified approaches and to provide the following information, where available: • Design procedure; • Typical thicknesses; • Construction considerations; • Specifications; • Performance; • Construction risks and issues; • Reason for any changes or modifications over time; and • Reasons for abandoning approaches, if applicable. Courtesy of John Coplantz. Figure 2.1. Example of plan section provided by the Oregon DOT.

10 The team also made field visits to projects constructed by the agency using renewal alternatives considered for inclusion in the guidelines. Details on these field visits can be found in Chapter 3. Test Cases In part of agency visits, the team and agency personnel iden- tified potential projects that could be used as test cases for comparing what the agency had done to application of the guidelines. Those projects were the following: • Michigan: I-75 in Cheboygan County; • Minnesota: I-35 in Chisago County; • Missouri: I-55 in Perry County; • Texas: US-75 Loy Lake Road to Exit 64; • Virginia: I-95 in Caroline County; and • Washington: I-5 in Skagit County (at Bow Hill). The data collected from each agency were used to develop a design report using the guidelines and interactive software. For each test case, feasible flexible and rigid pavement renewal strategies were developed and documented. The results were compared to the agencies’ standard design approach for the project. Only two of the test cases dealt with long-life designs by the individual agency. For the other four cases, the guide- lines were compared to current practice, which were 20-, 30-, or 40-year designs. Resource Development Considerable effort was taken to develop the resource docu- ments that go with the guidelines. There are approximately 400 pages of documents that were prepared to be used with the decision tables. Designing and building long-life pavements typically require more attention to detail than simple treat- ment selection and thickness design. Those details that should be considered in designing and building long-life pavements include the following: • Pavement assessment; • Best practices for flexible pavements; • Best practices for rigid pavements; • Guide specifications; • Life-cycle cost analysis; • Emerging technology; • Traffic considerations; and • Life-cycle assessment. A set of six resource documents were developed to address these details and are described in more detail in Chapter 3. Workshops Two regional workshops and a local pilot workshop were con- ducted to assess the guidelines. The team organized and facili- tated one pilot workshop in Washington and two regional workshops in Virginia and Missouri. The pilot workshop was held with Washington State Department of Transportation employees from design, materials, construction, and traffic divisions. Additionally, local contractors and industry repre- sentatives participated. Similarly, the two regional workshops were attended by representative departments within the agency, as well as local contractors and industry representatives. Adja- cent state agency personnel were invited to attend and public advertisement of the workshop was conducted in accordance with the agency’s protocols. Attendance by adjacent state rep- resentatives generally was not possible because of travel restric- tions. However, these representatives received access to all of the material and were asked to provide comments. The agendas distributed before each workshop contained information on the purpose and objective of the workshop. A link was also provided to the interactive guideline software and resource documentation so that attendees could complete some advanced reading and review of the material. During each workshop, presentations were provided on the resource documentation developed as part of the study, as well as results from the test cases. Several scenarios were dem- onstrated using the software. The group was asked for their comments and feedback based on the material presented at the workshop. All dialogue was documented and utilized to modify the deliverables of the project. Near the end of the workshop, each participant was asked to complete a questionnaire. Overall, the participants viewed the guidelines as valuable and useful. In particular, the resource documentation was viewed by attendees as a solid tool for pavement designers. All of the comments received were reviewed and addressed in the final guidelines.