The Superpave Mix Design System: Anatomy of a Research Program (2012)

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95 CHAPTER 5. IMPLEMENTATION PHASE This chapter summarizes the efforts to implement the results and products developed during the research phase of the program. It describes the groups involved and their roles in the implementation process; the funding, organization and leadership of the implementation efforts; and the continued evolution of the products. 5.1 SEEDS OF IMPLEMENTATION DURING THE RESEARCH PHASE With the research phase so short and intensely focused, it is safe to say that implementation of the research was not formally on the radar screen of the SHRP Executive Committee during the height of the research phase. That does not mean that it was not suggested that a plan for doing something with the research might be pursued, but it was certainly not on their continuing agenda. (Some instances where implementation was considered during the research phase were presented in Chapters 3 and 4.) “In hindsight, we should have had the technical advisory committees report directly to the Executive Committee and be tasked with developing an implementation strategy,” noted Frank Francois. This did not happen. In the third year of the program, some on the Committee suggested that implementation should be considered at some level. But it was probably not until the end of the program that the Executive Committee really started to focus on implementation. A possible catalyst to focusing on implementation was the successful international scan on asphalt technology in Europe in September 1990. This scan showed that the U.S. had not cornered the market on high quality pavements and that there was a lot to learn from other countries. Stone Matrix Asphalt, performance-based laboratory testing equipment, contractor quality control, etc., were all key items that were identified for implementation. The scan team also reported that the U.S. could benefit from reexamining some of the ways research and implementation were conducted. They noted that the results of research in Europe are “aggressively” marketed and that research and marketing go hand-in-hand, helping to ensure that successful research results are implemented quickly and effectively (15). This scan led to a stronger focus on implementation of the SHRP results. The scan team included representatives from NAPA and the DOTs who were strong advocates for change. Many ideas surfaced at the time and impacted how SHRP outputs would be addressed for the first time. Ideas generated included a catalog of products, regional asphalt User-Producer Groups, equipment procurements and the like. Much credit for the implementation focus goes to former Indiana DOT Chief Engineer Donald W. Lucas, who was on the Executive Committee. Also in 1990, the SHRP mid-course assessment meeting was held in Denver, allowing a large number of agency and industry personnel to meet with the SHRP researchers to review the progress to date and offer suggestions for the remainder of the entire research program. (The roster of attendees is in Appendix B.) This meeting marked the first major public discussion of implementation. In the opening plenary session, AASHTO President Kermit Justice observed that the involvement of the AASHTO member states would “intensify as SHRP moves into its second half.” He also urged the attendees to start using what they learned about at the meeting. “Research results do not put themselves in use automatically,” he said (3).

96 SHRP Chairman John Tabb also encouraged attendees to start thinking about implementation. He said, “We are counting on you to start the implementation effort here and now by going back home to champion the emerging products of SHRP within your own agencies.” He also recognized that implementation is a major effort, requiring “money, effort, time and patience.” He likened SHRP implementation to the advent of personal computing. “SHRP implementation … will require highway agencies to budget for new capital expenditures for equipment. We’ll have to expect a few problems at first as we work out the bugs. Some people will refuse to adopt the new ways of doing things. Some will resist change, but if we give them enough support, they will come around,” Tabb said (3). This statement certainly proved to be insightful as Superpave implementation progressed. At the same meeting, Dean Carlson announced the creation of a new position within FHWA’s Office of Technology Applications (OTA). Dick McComb, who had been FHWA’s first staff member on loan to SHRP, was named Special Assistant for SHRP Implementation. It is interesting to note that this position was created within OTA, not Research and Development, signifying that the products were deemed to be ready for implementation. As implementation assumed a greater prominence, the SHRP team developed several implementation documents, but it is safe to say that none captured the full imagination of the country. There was little grasp of how comprehensive and far-reaching the asphalt implementation efforts might be. In fact it was not until 1993 that the full thrust of the asphalt specification and the asphalt mix design system was defined and recognized by the broader highway community. As the research program was developed and refined, it changed gradually from a liquid asphalt research program to a mix design and analysis program as well. This change dramatically influenced how the results might be applied nationwide. The scope of work would require fundamental changes in more than just liquid asphalt formulations. The new scope of work would literally touch every DOT, hot-mix plant and inspector in the nation. At the mid-course assessment meeting, it was recognized that the adoption of the system – whatever shape it finally took – would require major expenditures by agencies and industry for capital equipment, training, changes in operations and material supplies, and more (3). In addition to the suggestion that these impacts should be quantified soon to help organizations prepare to implement Superpave, other implementation comments were also made at the mid-course assessment meeting (3). These included: • Circulating the proposed mixture test methods, including the compaction method, for review. • The issuance of draft specifications (“straw man” specifications) during the research phase was seen as a good tool to involve a wide range of people in the process and help them prepare for eventual implementation. • The concept of using User-Producer Groups and other industry task groups was supported as a short-term implementation strategy. The need for an early and comprehensive training program was also identified by those participating in the Asphalt -Aggregate Mix Specification Workshop during the mid-course assessment meeting.

97 5.2 TRANSITION TO IMPLEMENTATION Although the seeds of implementation had been sown earlier during the research phase, implementation planning activities increased markedly as the research phase drew to a close. During 1992, the groundwork was laid for the later implementation efforts in the SHRP offices and at FHWA. Implementation efforts began in earnest in about 1993. 5.2.1 Transition to Implementation at SHRP Program Office While many believe that there was little in the way of formal implementation at SHRP during the research phase, there was considerable discussion of what research would be used by the state DOTs and how they would use it. It was not until 1992, however, that the framework of an Implementation Plan was developed by the SHRP Program Office. It outlined eight main steps for implementation over a seven year time period, from 1993 through 2000, as shown in Figure 37. Additional details of other activities to support the main steps are shown in Table 11. Figure 37 Overview and Main Steps of Superpave Roll-Out Plan (circa 1992)

98 Table 11 Detailed Steps in the SHRP Program Office Implementation Plan (After Kulash, 1992) Year(s) Planned Implementation Activity 1993 - 1995 Pooled-Fund Study and Development of Precision/Bias Statements 1993 National Training Center in Operation 1995 University Professors Trained 1993 - 1994 AASHTO Adopts Superpave Standards 1993 - 1995 Development of Field Control Procedures (NCHRP 9-7) 1994 – 1996 LTPP SPS-9 – Field Proof Testing 1994 – 1998 Refinement of Superpave Performance Prediction Models 1994-1996 Superpave taught in standard university curriculum 1995 Establishment of Regional Training Courses with NHI 1995 Incorporation of Superpave QC/QA into joint paving handbook 1995-1996 State / Industry Training 1996 – 1998 LTPP Integration of Mix and Structural Design 1996 - 1997 Parallel Use of Superpave by States 1998 – 1999 Superpave in general use in most states 1998 – 2000 Superpave revised to incorporate SPS-9 results 2000 Application of Pay Factors based upon performance results This timeline was presented to the SHRP/TRB Committee by Gale Page on behalf of the SHRP Asphalt Advisory Committee in October 1992 and was sent to key individuals involved in Superpave implementation in November 1992 by Damian Kulash. The presentation provided the Asphalt Advisory Committee’s view of implementation as well as that of a state DOT (“AASHTO user agency”). The goal of the presentation was to look ahead at what would be needed to work together, move forward with a positive attitude, and raise the level of technicians. Implementation was seen as an “upfront and continuous focus” from the beginning of the program. There were seventeen items identified as early concerns regarding the specifications and tests, including the following: 1. AASHTO Approval 2. Definitive 3. Simple 4. Timely results 5. Reduced variability 6. Familiarity with test/training 7. Account for multiple effects 8. Equipment acquisition 9. Better end-product/ validation 10. Need for people/space/money 11. Allow for regionalization 12. Adaptable to QC/QA 13. Impact on local materials 14. Justification for resources 15. Priority with CAO/Commitment 16. Plan for implementation 17. Contractor/ Material supplier involvement

99 Ultimately, this boiled down to three major concerns about SHRP implementation: 1. The gap between management and materials 2. Concern about the level of validation 3. The need for a mechanism to carry on product development Finding the resources to continue the development of products and foster implementation was a major issue at this time. The needs for refinement, more research, validation of the binder and mixture products, and integration of the system with QA and field testing were recognized. FHWA was seen as the “primary working vehicle” for implementation with AASHTO, industry and the regional user/producer groups as partners. The immediate implementation needs included the resources to continue the efforts, a structure for ongoing coordination of efforts and support for that structure. Implementation was seen as a complicated process with several stages, illustrated by the “Valley of Implementation” (Figure 38). Status Quo Old Technology Adoption New Technology Mandate Interactive Stepwise Process Denial Fear Rejection Question Investment Acceptance Understanding Participation Analysis Figure 38 The Valley of Implementation

100 5.2.2 Transition to Implementation at FHWA While it is well-documented that FHWA did not play a lead role during the research phase, it was assumed that FHWA would be playing a role in the implementation of the research. Heretofore, the only major roles played by FHWA were Executive Director Dean Carlson sitting on the Executive Committee and FHWA Loaned Staffers Dick McComb and Paul Teng. The implementation efforts at FHWA began in 1992 and were expected to continue through the rest of the 1990s (16). Several barriers to the formal participation of FHWA existed at the time. The first was the lack of staff understanding, in any specific detail, of what was in the research program, how complete the work was, and what the full impact of the work would be. The second was the question of which FHWA organization would take the lead – the Office of Technology Applications (OTA) or the Asphalt Division at the Turner-Fairbank Highway Research Center (TFHRC). To address the first concern, FHWA staff members Ted Ferragut and John D’Angelo paid a visit to Damian Kulash and introduced themselves. Kulash presented his understanding of the implementation effort, which appeared to be a very aggressive top down approach that might take upwards of three years or so. He thought it a good idea for FHWA engineers to begin the process of understanding and learning what was in the program. This led to John D’Angelo focusing on understanding the binder issues. He visited Dave Anderson, which in turn led to a Denver meeting with other asphalt binder experts including Joe Goodrich, Gayle King, Mark Bouldin and Ray Pavlovich. They were meeting to look at Anderson’s work with master curves on each binder. The binder experts redirected D’Angelo to understand the individual test procedures, equipment and results. D’Angelo later expressed that he felt uncomfortable at the meeting, as if the presence of FHWA staff was perceived as meddling. The beginning of an answer to the second concern occurred in 1990, when Dick McComb was assigned Special Assistant for SHRP Implementation. The significance of this decision was that the responsibility for this effort was placed in the Office of Technology Applications, not the Office of Research. The thought at the time was that the research was completed and that implementation meant a program to apply the technology, not to evaluate it. This meant to all concerned that the work in Superpave and all the other areas was ready to use. Putting McComb in the OTA office clearly emphasized this assessment. The plan also included an aggressive plan for the continued refinement of the Superpave system and its adoption by the states and industry. In short, the plan called for the system to be finalized by 2000 and fully implemented by 2005.

101 5.2.2.1 1992-93 Implementation – FHWA Timeline One key element of managing the program was the establishment of a formal timeline to achieve acceptance of the binder and mix specifications and tests as standard practice. FHWA developed a timeline, shown in Figure 39, to guide implementation efforts. The timeline aimed to make the binder specifications the national practice by 1997 and the mix by 2000, by the majority of states. However, there was a more subtle reason for the timeline; senior managers associated with the Superpave research phase really had very little comprehension as to how long the road to adoption would really be. The FHWA timeline was an attempt to bring that point home. The timeline, for example, outlined the procurement time, prototype and first article testing, manufacturing time, and, of course, time to develop a basic understanding of the binder specification. That alone was a three year process. A similar process existed for the mix equipment and for training at the National Asphalt Training Center as well. This FHWA plan was developed as a result of a meeting between Ted Ferragut, Damian Kulash and John Bukowski (of FHWA). Ferragut and Bukowski showed Kulash the constraints of getting things accomplished at FHWA and around the country. They explained the time it took to buy equipment, to staff trailers, to set up training courses through NHI, etc. It was a good discussion and led to a realization of how long implementation would take and what items of work were necessary to accomplish all the goals. Neither group, however, really had a feel for the journey in the various states and the dynamics taking place within both the asphalt and hot- mix industries.

102 Figure 39 FHWA April 1992 Timeline for Superpave Implementation The implementation plan for Superpave that was eventually developed called for the following activities and organizations:  Pooled-Fund Equipment Purchase  TE19 Technical Assistance Program  National Asphalt Training Center (NATC)  DP90 Mobile Asphalt Lab Program In addition to these activities, other groups and efforts also played a role, as will be discussed in Section 5.4. SHRP POOLED FUND & TRAINING 1 9 9 2 1 9 9 3 1 9 9 4 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D POOLED FUND Binder Equipment Purchase #1 Proc. Strategy Procurement Delivery Purchase #2 Proc. Strategy Procurement Delivery TE 19 (LOAN EQUIP.) Procurement Delivery Workshops/State Evaluations Mixture Equipment SHRP 1st Art Testing Gryatory Compactor CBD REP AWARD Purcahse #1 Proc. Strategy Procurement Proposal Eval 1st Article Delivery Constr & Test Ruggedness Testing Purchase #2 Procurement Delivery SHRP Shear Tester REP AWARD Purcahse #1 1st Article SHRP Spec Development Procurement Proposal Eval Constr & Test Ruggedness Testing Purchase #2 & 3 Procurement Indirect Tensile REP AWARD Purchase #1 1st Article SHRP Spec Development Procurement Proposal Eval Delivery Purchase #2 Procurement Delivery Procurement Course Dev. & Tech Services Pilot Courses(10 ÷) / Tech Services NAT. TRNG. CTR Binder Mixture Pilot Shakedown DP 90 SHRP Gyratory/Volumetric Analysis Full SUPERPAVE MOBILE ASPHALT LAB

103 5.2.2.2 Pooled-Fund Equipment Buy Program (1992-93) One of the first major efforts of the FHWA Implementation Program was the acceptance of a pooled-fund study that would procure sets of binder and mix equipment for each state DOT. If there was a kick-off to implementation, this was probably the key activity. However, there was considerable work and effort behind this effort. The pooled-fund study was originally announced at the TRB Annual Meeting in January 1992. This was followed by a March 1992 meeting in Alexandria, Virginia. One representative from each state was invited to this meeting to discuss the equipment, how it was used, why it was needed, and how it could be procured for those states that wanted to participate. The idea behind the timing of the meeting was to begin rolling out the equipment before the end of the research phase to kick start implementation. This effort received considerable scrutiny. Real concern was voiced about FHWA’s aggressive role in organizing and managing this meeting. However, there were significant accolades as well about something finally happening. “This was a significant undertaking,” noted Haleem Tahir, then with the Maryland State Highway Administration. “It meant that we were serious in undertaking implementation. Having equipment in the hands of the materials engineers was the key to breaking down the barrier from theoretical to practical.” Each state had the option of receiving one set of binder equipment (bending beam, dynamic shear rheometer, the PAV, the direct tension tester, the rotational viscometer), a gyratory compactor, and the SST and IDT performance testers if they so desired. They also had a choice to select the first, second or third buy in the program. The total price for the equipment was $325,000 for a full set of equipment; the binder equipment was estimated to cost $98,000, the mix equipment $227,000 and $10,000 for training. All but one state eventually took advantage of the opportunity to buy the binder equipment (except the direct tension tester) and gyratory through the pooled fund, prior to 1996. The trailer with the binder equipment was on display at the March 1992 meeting, along with the resilient modulus equipment, the Rainhart Texas gyratory and the prototype Superpave gyratory. Also displayed were the Marshall hammer and the rotating base Marshall hammer. The SST and IDT were not initially ready for DOT use and were integrated with the Superpave Centers Program. Because of their complexity and expense, it was deemed appropriate to evaluate them on a smaller scale before outfitting every state with the devices. (The SST was estimated to cost $300,000 and the IDT $150,000 in 1997.) Critical to the success of the equipment buy was the strong desire by FHWA engineers to award dual contracts for each piece of equipment. “We did not want to be stuck with one supplier nationally; we were looking into the future,” noted John Bukowski, FHWA asphalt pavement engineer. “It took some real convincing of FHWA procurement to accomplish that. Coincidently, they had hired a procurement officer from the Department of Defense who was invaluable in getting the multiple awards through the procurement process.” SHRP did not release equipment procurement specifications as part of the research phase. It took considerable time working with the researchers, equipment manufacturers, and key DOT engineers to develop these specifications. “We had to stay away from method specifications and brand names and describe the performance of the equipment. We concentrated on that aspect for all the equipment. We used a two-step concept in the buy, looking for the first article to pass

104 rigorous testing followed by the manufacture and shipment of the approved equipment,” remembered D’Angelo. 5.2.2.3 Superpave Loaner Equipment (1992) Under TE 19, the Superpave Technical Assistance Program, FHWA bought five sets of Superpave equipment to lend to the User-Producer Groups to help make the industry more familiar with the new equipment and procedures. This was a key step prior to the pooled-fund equipment buy. Several of the regions moved them around in trailers (University of Utah, Penn State University, and National Center for Asphalt Technology); others set them up in one place (Arizona DOT, Indiana DOT). Dave Anderson was also hired to conduct binder workshops with this equipment. Anderson and others, including his graduate students, provided assistance with setting up the equipment, provided training, advised on data analysis and performed other activities. FHWA support staff also provided technical support and training in state labs and trained visiting engineers and technicians from private labs in the binder lab at Turner-Fairbank. By 1996, FHWA support staff had visited at least sixteen states to provide hands-on training and support. 5.2.2.4 National Asphalt Training Center (1993) The implementation effort called for the development and initiation of the National Asphalt Training Center (NATC). The Asphalt Institute was awarded that contract in September 1992. A second, five-year contract was awarded to the Institute in September 1995 for NATC II. It called for hands-on training for the first wave of DOT engineers and lab technicians. The concept was to train the technician or engineer in a formal setting, promote dialogue, and break down the anti-change atmosphere that surrounded Superpave implementation. Training slots for one binder technician and one mix technician were allotted to each DOT, with priority given to DOTs buying equipment on the first and second buys of the program. The first course taught was a binder training course in July 1993. Demand for training was high; by the fall of 1996, 18 binder and 18 mix courses had been taught, training over 700 engineers and technicians from agencies, industry, FHWA and universities. Pilot one and two- week courses on the mix analysis system were also developed and presented under NATC II. The Institute continued to offer the binder and mix training after the second contract expired (on a fee basis). Additional activities performed by the Asphalt Institute are described in 5.4.7. 5.2.2.5 The Trailer Program (1991) FHWA had been working with an asphalt trailer from 1986 on under Demonstration Project 90, looking at volumetric controls for hot mix. The concept was to use Marshall volumetrics during construction. This work gave the FHWA staff exceptional experience in understanding hot-mix production variability, including the connection between mix design and quality control. Eventually, this work was recognized by the Association of Asphalt Paving Technologists in 1991 with the W.J. Emmons Award for the best paper. This work was important for several reasons, since it showed that:

105 1) the FHWA could transition to Superpave or AAMAS, and 2) the FHWA could work with the new equipment and provide hands-on expertise to the states. FHWA quietly began the procurement of two additional trailers, anticipating the demand for Superpave evaluation and training. Two trailers would be dedicated to mix design testing and evaluation projects. The third trailer would be dedicated solely to binder equipment testing, including ruggedness and precision/bias testing. The trailers were intended to support the SPS-9 studies and also developed mix designs and assisted in construction quality control (QC) testing at WesTrack. [1996 FHWA Implementation Status Report] A key element of the trailer program was providing hands-on demonstrations of the test equipment to aid implementation efforts in the states. The work at the trailers was performed in two ways. Current mixes used by the states were tested according to the SHRP protocols and compared to the Superpave standards. In addition, true Superpave mixes were designed and analyzed using the available materials. The trailers also included a training component. A one to two-day workshop was offered at each site the trailers visited. 5.3 FOCUSED IMPLEMENTATION BEGINS: THE ISTEA YEARS In 1993, the SHRP research was concluded and the implementation phase began in earnest. The SHRP Program Office had made some efforts at implementation during the research phase, but in essence, the research curtain had fallen and the implementation curtain was raised in 1993. Efforts initiated in 1992 continued while many new efforts were undertaken. While the research phase ended in 1993, the SHRP office on Connecticut Avenue remained open until June 28, 1994. The last year was spent, by an ever-dwindling staff, publishing reports, closing contracts and other close-out activities. Planning for implementation was one of those close-out tasks. The status of Superpave at the time was later summarized by Tom Harman from FHWA (17). The products at the end of the research phase consisted of research grade prototypes of equipment without biddable specifications and few to no manufacturers; test methods that were not yet AASHTO standards; limited test sections (fewer than 1000 tons of mix had been placed); and a small circle of people knowledgeable about the technology. Estimates of the number of knowledgeable people were that there were no more than 30 engineers and scientists, no more than ten executives and no more than two contractors who were truly in the know. 5.3.1 Funding and Managing the Implementation Phase Congress had allocated funds to FHWA for implementation of the SHRP results in the 1991 Intermodal Surface Transportation Efficiency Act (ISTEA). Surprisingly, the funding was provided with no strings attached, meaning FHWA and its implementation partners could use the funds as they saw fit. This opened the door to some new, innovative and aggressive

106 implementation approaches. The key to the entire implementation program was this line item for SHRP implementation at the level of $50M, in addition to FHWA’s normal technology development funds. (An additional $58 million was provided in the same legislation for the continuation of the LTPP program.) The path by which this implementation funding came about at this critical time is not very clear or well-documented. It is also unclear how FHWA eventually got the lead implementation responsibility. All paths appear to have gone through Tom Larson. Larson had moved from the Pennsylvania Department of Transportation to FHWA as the Administrator. He believed that FHWA was well positioned to do technology implementation since it had research and technology application arms in Washington and field offices throughout the country. Immediately, many questions began to surface:  Should FHWA actually lead this State-designed and State-managed research program? If so, who at FHWA was in charge?  Would there be a committee structure?  What were the first two or three activities?  What about the research? Was it really finished?  What was the long-term goal?  Where do we get the needed equipment?  What are the test protocols?  How do we train people?  Who really knows that this works?  What does implementation really mean? After many draft plans were considered, detailed implementation plans were developed for SHRP as a whole (18) and for the Asphalt products in particular (19). The overall purpose of SHRP implementation was to apply those research findings that would improve the quality, efficiency, safety, performance, and productivity of our nation's highway system. For the first time, implementation was defined. The overall plan stated (18): Assuming that implementation means "bringing into practice" or "carrying out the means to bring into practice", there are essentially three levels of first-stage implementation that will be carried out in this program. The three levels are necessary since the SHRP products generally fall into one of the following categories: 1) those that are essentially complete, available for widespread use, and can be deployed with minimal training or field/laboratory evaluation. 2) those that will require local State/industry field and laboratory test and evaluation along with significant training prior to general acceptance and use. 3) those that are incomplete without continuation of the research and/or must be integrated with other ongoing research prior to use. Grouping implementation this way established an important departure from SHRP advertising and outreach efforts. Heretofore, the country was led to believe, rightly or wrongly, that all SHRP products were ready for implementation and adoption. This was reinforced with the issuance of the SHRP Product Catalog with nearly 150 products described as ready-to-go. In point of fact, however, all those products were not ready for widespread implementation; this was certainly true of the asphalt products.

107 In this plan, the goals of the implementation process were defined as well (18):  To fully and professionally communicate final SHRP research findings to the US highway community.  To immediately bring into voluntary practice those SHRP products and techniques that are essentially complete and are implementable with minimal training and/or evaluation.  To promote field and laboratory testing of those SHRP products that require use of local materials and adaptation to regional, State or specific industry practices.  To advance those promising but only partially completed SHRP products/processes through further research, development, test and evaluation, standard setting, and institutional awareness.  To provide early exposure and training on the use of SHRP products and initiate activities that will enhance long-range educational efforts.  To develop and implement both short and long-range marketing strategies for SHRP products by taking full advantage of existing industry delivery systems.  To promote activities by standard setting organizations – AASHTO, the American Concrete Institute (ACI), ASTM, etc. – that enhance the acceptability and credibility of the SHRP products. The Plan also looked at what might happen to implementation should elements outside the control of FHWA come into play. Successful implementation identified the following dependencies (18):  Top executive awareness, understanding, and support of the program - State, Federal, and industry - and continued promotion of the highway program and progressive and technology centered.  Full and continuous Congressional financial support.  Effective use of State apportioned Federal-Aid highway research funds to test and evaluate SHRP products.  Continued voluntary State and industry participation on technical working groups and Expert Task Groups.  Proper integration of research scope and findings from various programs and organizations - FHWA, National Cooperative Highway Research Program (NCHRP), Corps of Engineers (COE), Federal Aviation Administration (FAA), private sector, etc.  5.3.1.1 1993 Organizational Direction - FHWA As noted earlier, Dick McComb had been appointed the Special Assistant for SHRP Implementation in 1990 and had been assigned to OTA. This implied that the research was complete and products were ready for implementation. Since 1990, however, awareness had grown that there was a need for additional research and development efforts before the research results would be ready for implementation. This awareness led to the establishment of a three tiered management structure. The Office of Technology Applications remained the lead office directing the implementation efforts. SHRP Implementation Coordination Group (SICG). The mission of the SICG was to oversee the implementation efforts by the Federal participants and to ensure that that State, industry, and

108 academia are kept informed of implementation efforts and issues. This internal FHWA group coordinated activities as appropriate with other interested groups, including the TRB-SHRP committee. It included just about every major office manager in FHWA but worked behind the scenes and was not very visible to others. Technical Working Groups. Membership in the TWG's included a cross section of FHWA, State Highway Agency, academia, and industry representation. The Asphalt TWG was appointed to deal with technical issues related to Superpave implementation. The general responsibilities of the TWG's included the following:  Receiving and identifying SHRP products.  Assessing and evaluating the technical nature of SHRP products.  Identifying potential technology development, implementation and marketing strategies.  Recommending the establishment of specific Expert Task Groups under the Technical Working Groups.  Reviewing the work of Expert Task Groups that are addressing details of specific technologies.  Coordinating with and involving additional technical partners, technology users and producers, as required.  Identifying resource needs.  Executing implementation programs aggressively and professionally. Expert Task Groups. Expert Task Groups (ETGs) were named to address specific topics for the various SHRP research areas. In the case of Superpave, there were three ETGs: binder, mix, and performance modeling. The composition of the ETG's included a cross section of FHWA, State Highway Agency, academia, and industry representation. The roles of these ETG's were to provide technical oversight of various technical efforts. The Office of Technology Applications addressed several key functions for FHWA. They included:  Tracking and controlling the financial affairs.  Publishing and distributing newsletters, promotional documents, publications and exhibits.  Developing and maintaining a product database One key part of the plan, however, was to assure that all of SHRP implementation was done with coordination, cooperation, and collaboration with the program offices. This led OTA to work very closely with the Offices of Program Development, specifically the Pavements, Construction and Maintenance, and the Structures Divisions, to allow them to take on a more prominent role in the program and to provide technical staff to execute the specific projects. This was easier said than done and caused considerable internal friction at first. OTA had a rather wide latitude to work with DOTs and industry while keeping the field offices informed. The Operating Offices were used to issuing policy, guidance, and regulations – more command and control functions. One final element of the program was to establish regional SHRP implementation technical coordinators. In response to a July 1992 memo from Executive Director Carlson, the nine FHWA regions and the Federal Lands Offices assigned personnel to coordinate activities within a certain

109 technical area. While a significant element of the assignment was to coordinate the flow of information, the need for more technical involvement was paramount in order to make the transfer timely and effective. In hindsight, the Superpave program taxed the OTA staff for the first three years of the program. “We had to understand the technology and train ourselves, develop and implement procurement contracts for equipment, give technical assistance to the DOTs and industry, participate in non-stop conferences and workshops, and prepare articles and news releases,” noted John D’Angelo. “We also had to train and work with the entire FHWA organization to assist in this culture change that was underway. It was very difficult. If we had to do it over again, we would have trained our FHWA people first and set up more, stronger regional technical assistance programs for the DOTs.” Ferragut noted that this was one of the goals with setting up the Superpave Centers. “I did not think at OTA we could ever work with 50 DOTs, the FHWA, and the industry. Nearly all the work was coming through three engineers and a manager at FHWA Headquarters. No one really wanted to hear about the challenges, only when Superpave was going to be adopted.” 5.3.2 Implementation in Full Swing Under ISTEA, then, the Superpave implementation efforts really took off. FHWA had a significant amount of funding and had started many implementation efforts to further develop and refine Superpave and move it into routine practice. Soon the situation was going to change radically with the passage of the Transportation Equity Act for the 21st Century (TEA-21). Before discussing TEA-21 and its impact on Superpave implementation, the next section will discuss some of the other groups and activities that were initiated, often with FHWA support, during the first part of the implementation phase.

110 5.4 KEY GROUPS AND ACTIVITIES FOR IMPLEMENTATION Under FHWA during the first phase of implementation, several groups became active in the Superpave implementation efforts – some were spins offs of existing organizations and others were new entities developed specifically to participate in Superpave implementation. Most of these groups and activities are still in existence though they have adapted to changes in the status of implementation. This section describes these groups, their organization, funding and activities. These groups include the Superpave Centers, AASHTO, the Lead State Team, the User-Producer Groups, the Expert Task Groups, TRB and the Asphalt Institute. Some activities were focused around Washington (at FHWA, TRB and AASHTO) and others took place across the country on a regional or local level. The common thread between all of these groups was FHWA, which was working to coordinate activities across the country. 5.4.1 AASHTO As pointed out earlier, the SHRP Research Program was funded by a take-down from the states’ Federal-Aid funding. The SHRP products were intended to be implemented by the states. Clearly, then, the states needed to be heavily involved in implementation efforts. The main vehicle for involving the states was AASHTO. 5.4.1.1 SHRP Research Implementation Coordinator One of the steps AASHTO took to facilitate implementation of the SHRP products was to hire Haleem Tahir as SHRP Research Implementation Coordinator, using funds provided by FHWA, to coordinate and provide support to the various contributors to SHRP research implementation, particularly the Subcommittee on Materials. The FHWA and the Lead States Team relied extensively on Tahir through the process. Tahir connected the AASHTO Subcommittee on Materials (SOM) with FHWA and the Lead State Team, as well as the FHWA TWG and ETGs. He held the position for over ten years, shepherding the provisional standards through to full standards and keeping the community informed of implementation progress. Tahir had been with the Maryland State Highway Administration, so had a deep appreciation of issues the states would face as implementation proceeded. He also had familiarity with the SHRP Research Program and with his former colleagues from other states, whom he would continue working with in his new role. 5.4.1.2 Provisional Standards Recognizing that the SHRP Program would create an unprecedented need for the rapid development of new standards, AASHTO, through Tahir’s leadership, created a new class of standards, known as provisional standards. These were intended as “dynamic” standards for immediate use by the states, with the understanding they would be revised or updated more frequently than mature standards. This change has been credited with being extremely important for the eventual implementation of Superpave. Provisional standards got the methods out there for people to use while still making it clear that refinements would be likely. Past experience has shown that rolling a product out before it is really ready for implementation and then finding

111 problems can be the death knell for the product. Those early users get a bad taste in their mouths and may not be willing to try a second time. Ron Sines, then with the New York State DOT, was deeply involved in revisions to the provisional standards. Following a Lead State Team meeting in Baltimore in 1997, Sines began assembling information to guide the somewhat extensive revisions. Members of the Lead State Team met after the Mix ETG meeting in Orlando in March 1998 and reviewed the proposed changes. The revisions included increasing the density at Ninitial from 89.0% to 91.5% for lower volume roads to allow the use of finer mixes and lower fine aggregate angularities. Another major change was the simplification of the aggregate property tables. Since many of the people who voted on the AASHTO ballots had little to no experience with Superpave, Sines wrote white papers explaining why changes were needed and how the proposed changes would address the problems. These were instrumental in getting the changes approved through AASHTO. 5.4.1.3 Task Force on SHRP Implementation The Task Force on SHRP Implementation was created by AASHTO in 1991 to develop plans to further the implementation of the SHRP research products. The task force collaborated with a number of other entities, including the SHRP Program Office in its early years and FHWA, TRB, the AASHTO states and the private sector throughout its life. The task force sunset in 2000, with its mission largely accomplished. The task force was chaired by B. F. Templeton from the Texas DOT. Templeton was succeeded by John Conrad from Washington State in about 1998. See Table 12 for the members of the task force. This task force would prove instrumental in securing funding to support implementation efforts when TEA-21 severely limited FHWA’s funding. In addition, the task force created the Lead State Team concept described in 5.4.3. Other key recommendations from the task force included supporting the establishment of the pooled-fund equipment purchase, the creation of the SHRP Research Implementation Coordinator position at AASHTO, and a number of resolutions passed by AASHTO committees. The task force’s major initiative was the Lead States Team. The task force was also involved in supporting the Superpave Centers, the LTPP program and the SHRP assessment project. (The Superpave Centers are discussed in detail in 5.4.2.) The task force supported the LTPP program by encouraging states to construct test sections and planned to oversee implementation of products from LTPP as they became available.

112 Table 12 Members of AASHTO Task Force on SHRP Implementation Member Representing Joe Mickes (1996-97) Missouri DOT Bob Templeton (1996-97) Texas DOT Ken Shiatte* (1996-97) New York State DOT Joe Deneault (1996-2000) West Virginia DOT John Conrad (1996-2000) Washington State DOT Haleem Tahir (1996-99) AASHTO Staff Amy Steiner (19960 AASHTO Staff Dwight Bower (1997-98) Idaho DOT Don Lucas* (1997-2000) Indiana DOT Linda Thelke (1997-99) Wisconsin DOT Eugene E. Ofstead (1997) Minnesota DOT Larry R. Goode (1997-98) North Carolina DOT Gary L. Hoffman (1997-2000) Pennsylvania DOT Gary Carver (1998-99) Wyoming DOT David Ekern (1998-2000) Minnesota DOT A. R. Giancola (1998-99) National Assn of County Engineers Douglas Rose* (1998-2000) Maryland DOT Don Goins (1999-2000) North Carolina DOT Jim Ross (1999-2000) Idaho DOT Mike Halladay FHWA *Primarily working with Superpave Lead State Team. The SHRP assessment project was a communication effort to share the “practical successes of implementing SHRP technology” through a series of flyers called Road Savers. One of the most significant Road Savers issues was the 1998 report “Assessing the Results of the Strategic Highway Research Program.” This benefit-cost study of SHRP (not just Superpave) was conducted in 1996-97 by the University of Nevada – Reno (UNR). Through case studies, the report showed that Superpave projects were “holding up well to heavy traffic and extremes of climate.” They predicted that adopting the binder specifications alone could increase service life of an overlay by 25% (from 8 to 10 years) and that if all agencies adopted the performance grade specification within five years, the increase in service life, based on a nationwide average, could save $637 million per year. Fewer maintenance related delays (user costs) and less vehicle maintenance could save motorists $1.7 billion per year over 20 years if the binder specifications were implemented within five years. This report was the first to put hard dollars to the benefits of implementing Superpave (20). 5.4.1.4 SCOH, SOM and SCOR The AASHTO Standing Committee on Highways (SCOH) is the parent committee that oversees the activities of its subcommittees. The representatives are usually the chief engineers or other technical members of the state DOTs. It is a highly influential group responsible for the development of policies, standards and guidelines. Resolutions approved by SCOH carry much weight, as they reflect the backing of the high ranking members of the state DOTs.

113 Subcommittees under SCOH include Design, Construction, Materials, the Technology Implementation Group (TIG) and more. (The TIG is essentially modeled after the SHRP Product Implementation Task Force and is charged with championing research products that are ready for implementation.) SCOH authored or endorsed several crucial resolutions in support of Superpave or various implementation strategies. These resolutions included a 1997 resolution urging all states to implement the Superpave products uniformly (21); this resolution was ultimately unsuccessful but was a valiant effort. SCOH also passed a resolution in 1997 in support of the Superpave Centers that encouraged states to participate in and help fund the Centers’ activities (22). The resolution had been initiated by the AASHTO Task Force on SHRP Implementation. That Task Force also formulated a 1998 resolution supporting SHRP implementation activities and the LTPP program that help to fill the funding gap created by TEA-21, which was supported by SCOH (23). The Subcommittee on Materials (SOM) has the authority to publish and keep current specifications for materials used in the construction and maintenance of all transportation facilities, and specifications for standard methods of sampling and testing such materials. Therefore the SOM assumed the responsibility for publishing and updating all the Superpave- related standards, including the important provisional standards. The Standing Committee on Research (SCOR) is focused on ensuring that high quality research is conducted to meet the needs of the state departments of transportation. SCOR also looks ahead to implementation of the research findings. SCOR has been essential in securing the needed follow-up research—on the order of $20 million between 1993 and 2005—that helped to enhance, refine, and close gaps in Superpave. 5.4.2 Lead States Team (1996-2000) In 1996, a new entity emerged in the implementation arena. The AASHTO Task Force on SHRP Implementation had been discussing the status of implementation across the country. As is typical with implementation of most new technologies, particularly in the highway industry, some states were much further along with implementation than others. The task force surmised that the learning curve for other states could be shortened if those states with more experience would share their practical, real-world expertise. Thus, the idea of the AASHTO Lead States was born. While the actual source is hard to trace, credit for the concept probably goes to a host of people including Bill Burnett and B. F. (Bob) Templeton of TxDOT; Joe Toole and Byron Lord of FHWA; Joe Mickes, Missouri DOT; Don Lucas, Indiana DOT; Haleem Tahir of AASHTO and others. “I think the concept of Lead States probably popped up in the midst of some negativity about SHRP,” recalled Bob Templeton. “Quite a few DOTs were floundering; lots of negativity had surfaced. Superpave was part of the negativity. It was recognized, however, that a few states were doing just fine with Superpave. From that kernel came the idea that maybe those that were [successful] with the technology could help those that were struggling.” The task force felt a cooperative effort to adopt new technology would be a benefit. They cited the following advantages (24):  Economic benefits from sharing resources,  Reduced duplication of efforts,  Teamwork,  Reduced burden on any one state,

114  Faster implementation, giving states the benefit of earlier cost savings, and  Better understanding of the technology and end results. In June 1996, Task Force Chairman Templeton wrote to six states inviting them to assume the role of Lead States for Superpave implementation. The six selected Superpave states – Florida, Indiana, Maryland, New York, Texas and Utah – accepted and agreed to share their experiences, both good and bad, with other states to promote more rapid implementation of the technology. As a Lead State, the participating agencies expressed their commitment to implementing the technology and helping other states do the same. The concept of a Lead State was that those states would share their “proficiency and knowledge … with others in order to advise new users of potential benefits and shorten their learning period” (25). Lead States were expected to:  with other states using a variety of means. In August 1996, Templeton wrote again to the six Superpave Lead States asking them to identify their representatives, champion(s) and industry representatives to be included as members of the team. (The resulting Superpave Lead State Team membership is shown in Table 13.) The involvement of industry in the process was seen as a critical element, since individual contractors or material suppliers typically did not share their expertise readily with other contractors, who are their competitors (25). The first meeting of the Lead State team was held September 18-19, 1996, in St. Louis, Missouri. At that meeting, the members of the team developed a mission statement and action plan. They also identified key milestones, available resources, challenges and communication between the members. The Superpave Lead State Team developed the following mission statement (24): The Lead State will assist in the uniform implementation of the Superpave system (Superior Performing Asphalt Pavements) by documenting and sharing experiences, furthering development and providing guidance related to the practical application of the technology. The individual goals and strategies they planned to achieve the mission are detailed in Table 13. Table 13 Members of the Lead State Team for Superpave (24) Member State Representing Paul Mack, Team Leader New York DOT Kenneth W. Shiate (later D. Rose, MD, and J. Deneault, WV New York AASHTO Task Force Liaison Gary Owens New York FHWA Jim Musselman Florida DOT Larry Smith Florida DOT Gale Page (1999) Florida DOT Cynthia Lorenzo (1996) Florida DOT (Public Information)

115 Jim Warren Florida Industry Rick Smutzer (later David Andrewski) Indiana DOT Gerald Huber Indiana Industry Rebecca McDaniel Indiana Superpave Center Lee Gallivan Indiana FHWA, IN Division Larry Michael Maryland DOT Jim Dunne Maryland FHWA, Region 3 Jitesh Parikh Maryland FHWA Maghsoud Tahmoressi Texas DOT Erv Dukatz Texas Industry Gary White Texas FHWA, TX Division Wade Betenson Utah AASHTO SCOH Liaison Cameron Peterson Utah DOT Gerald Barrett Utah DOT Mike Worischeck Utah Industry Tim O’Connell Utah Industry Tom Harman FHWA HQ Technical Resource Gary Henderson FHWA HQ Superpave Delivery Team Jeanne Fuchs Missouri Facilitator Martin Delaney (1999) Nova Scotia Transportation and Public Works

116 Table 14 Superpave Lead State Team Goals and Strategies Goal Strategies 1. Develop local state pool of technically experienced people to assist with pilot projects in design, construction, and trouble shooting by January 1997 a. Identify key people in each Lead State: i. Key contact and technical experts ii. List association, position and area of expertise iii. Action steps 1) Collect names 2) Publish and distribute b. Resources: Use FHWA to compile and make initial distribution. Suggested routes to distribute names: i. User-Producer newsletters ii. FOCUS publication iii. Roads and Bridges, Better Road, etc. iv. AASHTO Journal v. World Wide web (www) 2. Provide channel of communication for Superpave users and implementation partners a. Utilize internet as a clearing house for Superpave issues b. Utilize print media to provide current Lead State activities and update on Superpave issues 3. Set up data collection system by June 1997 a. Quarterly surveys b. Develop procedure to capture information from Goal 1 c. Develop a “system” for disseminating results of collected data and information d. Develop procedure to capture info from other sources 4. Get each state and agency to develop a realistic plan for Superpave implementation by October 1997 a. Provide “template” of typical implementation plan (ex. New York State) b. Work through User-Producer Groups (UPGs) c. Identify management level person to champion Superpave (agencies) i. Get management commitment ii. Set up communications between technical level positions iii. Offer assistance of Lead State iv. Encourage participation in U-P G d. Encourage partnering between users and producers at program and project levels 5. Identify training needs and available resources a. Provide list of potential training needs for Superpave implementation b. Provide list of available resources for meeting Superpave implementation training needs 6. Ensure Superpave Regional Centers actively support Superpave implementation a. Manage data collection system b. Coordinate with regional Superpave Centers on technical activities, construction, training and trouble shooting c. Representation on Regional Superpave Centers’ Steering Committee by Lead States d. Promote Regional Superpave Centers to provide referee PG

117 Binder testing services. The Lead State Team continued meeting in St. Louis annually through September 2000. (See Table 15.) At the meetings, the team reported on activities during the year, reviewed and refined goals, brainstormed new goals, and more. Table 15 Lead State Team Workshops Year Conference/Workshop Title 1996 Lead States Take the Lead in SHRP Technology Implementation 1997 Leading the Technology into the 21st Century 1998 Leading the Technology into the 21st Century: Sustaining the Momentum 1999 Leading the Technology into the 21st Century: Preparing for the Future 2000 Sunset to Sunrise The Lead States Team worked very closely with the AASHTO Subcommittee on Materials (SOM). The Lead States’ plans for implementing the Superpave system included a strong linkage to the appropriate Technical Sections. The Superpave Lead States Team also worked as a go-between for follow-up NCHRP Superpave research projects and the AASHTO SOM. They recommended significant advancements to four mix standards based on this research, as well as their own guidelines. SOM adopted the recommended improvements, publishing them in the May 1999 interim edition of the AASHTO Provisional Standards. One interesting issue the Lead State Team had to deal with was the lack of access of DOT personnel had to the internet (and industry was typically even further behind). In 1997, for example, the task force noted that use of internet to communicate between team members “has more than doubled in a year” but that there were still some DOTs without internet access. This seems hard to believe today, when most people carry internet access with them everywhere through their cell phone. The facilitator, Jeanne Fuchs, was provided for the Lead State Team meetings by the Missouri DOT and was invaluable in keeping the team focused on the task at hand. Since all the meetings were held in St. Louis, the facilitator was able to continue to work with the team through the duration of the program, establishing a strong rapport. The following are among the activities that the Superpave Lead State Team accomplished (26): • Completed a survey in February 1997 to assess the level of training that would likely be required in the areas of binder testing, mix design, and QA. A total of 39 states responded to the survey and indicated that over 1,000 people would need binder training and nearly 4,000 people would need mix design and QA training. Training needs for FHWA, executive staff and management, field personnel and others were also identified. • Produced a marketing video entitled Superpave … Tomorrow’s Pavements Today to promote Superpave to upper level staff in agencies and industry. (This was produced by the New York State DOT and the FHWA Division Office.) • Provided guidance to the AASHTO Subcommittee on Materials concerning recommended changes to the Superpave specifications in 1997.

118 • Recommended high-priority research topics to FHWA and the Mixture Expert Task Group including reevaluating Ndesign, investigating the need for different VMA values for fine and coarse aggregates, and addressing field construction concerns. • Established a Lead State website for dissemination of information. • Developed guidance statements (on Ndesign, fine aggregate angularity, coarse aggregate angularity, reclaimed asphalt pavement, field construction concerns and the use of modified binders) that could be applied within the Superpave system to encourage uniform implementation. This guidance was distributed to all states. • Completed influential annual implementation surveys in 1997 through 2000, charting the progress of implementation nationwide. These surveys were distributed to all members of SCOH, SOM, the Lead States, FHWA, the User-Producer Groups, Superpave Centers and industry. They served as the basis for countless presentations and publications. This benchmarking effort did much to encourage states to adopt the system and to convince various industry partners of the national commitment to its adoption. • Published a list of experts willing to be contacted to provide a variety of technical advice through the FOCUS magazine and other publications (Superpave center websites, trade publications and others). • Developed an example implementation plan to illustrate the issues states should address in their own plans. This guide was also distributed to all the states. Champions to lead Superpave implementation were identified in some twenty states by mid-1997. • Defined the “unchangeable core” of Superpave that must be maintained to implement a uniform plan. Recognized that some elements of the original Superpave system would be changed at a state or regional level, but attempted to identify those elements that could not be changed without irreparable damage to the overall system. • Provided a list of Superpave training resources and providers to the LTAP Centers and via the internet. • Issued 1998 Lead State guidance on the practical application of Superpave. This report was distributed to all states in 1998 and was reported on in FOCUS, FHWA Superpave Update, the Asphalt Contractor and via the internet. • Established liaisons from the Lead State Team with all the Superpave Centers. • Encouraged the passing of a resolution by the AASHTO SOM and Subcommittee on Construction urging uniform implementation of the Superpave system. • Sponsored a number of conferences and workshops on Superpave implementation in conjunction with the FHWA.

119 5.4.2.1 Lead State Guidance The Lead States periodically released guidance, formally and informally, to assist states and industry. One of the main documents was released in June 1998 following a March meeting in Orlando with FHWA and a number of states. The group met to discuss a variety of technical issues. The discussions suggested that there were steps states could take to ensure successful implementation, which were then outlined in the document. The Lead States were still striving to achieve uniform adoption of the Superpave system, so the recommendations in the guidance document were also referred to AASHTO as proposed revisions to the standards. The 1998 guidance dealt with the following issues (27): • Determination of the appropriate Ndesign level for a project. • Use of a 20 year design life for estimating traffic regardless of the actual expected service life of the pavement. • Lowering the Ndesign level by one increment for mixtures located more than 100 mm below the pavement surface. • Using previous state specifications for aggregate properties if those standards are more stringent than the Superpave standards. • Adopting the Superpave Mixture Expert Task Group’s recommendations for using reclaimed asphalt pavement in Superpave mixes. • Increasing the upper end of the allowable dust to binder ratio for coarse-graded Superpave mixes. • Using the aggregate bulk specific gravity to calculate VMA or accounting for the use of the aggregate effective specific gravity by either increasing the VMA criteria or determining a correction factor to adjust the VMA. • Clarifying that short-term oven aging should not be applied to plant-produced mixtures, since they have already been aged during production. • Changing the Ninitial criteria for low-volume roads. • Widening the acceptable range of VMA values (through modification of the voids filled with asphalt (VFA) criteria) for 9.5 mm mixes. • Issuing guidance regarding the use of Stone Matrix Asphalt (SMA) mixes under the Superpave system. 5.4.2.2 Superpave National Implementation Surveys One of the most frequently cited accomplishments of the Superpave Lead State Team was the collection and dissemination of nationwide implementation information through annual surveys. The first of these was completed in May 1997 to document the status of implementation through 1996. As an indication of the level of interest, 48 of 50 states, plus the District of Columbus and Puerto Rico responded to the survey. While the amount of Superpave mix placed varied by state, the overall average amounted to only 1% of total projects and 2% of total HMA tonnage nationwide. A total of 47 states had implementation plans by 1996, but only 19 of these were in writing. Figure 40 summarizes the results of the annual surveys and demonstrates the generally rapid growth of the technology through the increase in the number projects. By the year 2000, when the Lead States Team sunset, the survey showed that performance-graded binders had been fully implemented by 48 states (including DC); one additional state and Puerto Rico had plans for implementing the binder specifications. The last survey also showed that Superpave mixture

120 specifications had been fully implemented by 25 states and 15 additional states had implementation plans in place. Figure 40 Superpave Projects Awarded and Planned (in 2000) (28) In each survey, respondents were asked to identify what they perceived to be the barriers to implementation. From the beginning, industry acceptance, state budget restrictions and facility limitations were cited as primary barriers. Institutional issues were less frequently cited. Other potential barriers included limited knowledge about and experience with the system, as well as training for agency and industry personnel. Facility limitations declined steadily from 1997 on, presumably as states implemented their plans and obtained the needed equipment. Other implementation issues that were noted in 1999-2000 included lack of validation, high turnover of experienced personnel, QA implementation, and others. Training and lack of knowledge continued to be issues for some states, but were not as frequently cited as in previous years. 5.4.2.3 Transition Plan The Lead State teams were programmed to “sunset” in 2000. A fixed duration was set for the groups to provide time for their work to be accomplished without establishing a continual entity. The thinking was that at some point in the not-too-distant future, the work of the teams would be complete and the implementation would be fully mature, though there might still be some remaining issues. Accordingly, the Lead States developed a transition plan to describe those steps necessary to continue to advance Superpave technology in the absence of the Lead State Team. Although Superpave implementation had grown dramatically, in 2000 it was still not fully accomplished and there were remaining research needs. The team recognized the following elements that it deemed critical to the further development of Superpave technology (26):  Leadership 0 500 1000 1500 2000 2500 3000 3500 4000 2000 1999 1998 1997 1996 Projects Awarded and Planned

121  Expert advice  Expert user support  Long-range plan for research  Standards adoption  Visibility  Communication  Coordination  State-of-the-art implementation  Technology transfer and training  Universal implementation Recommendations were made in each of the areas above for what needed to be done and what organization should assume responsibility for ensuring completion. The details are probably not important here, but the fact that plans were made to continue the effort is. In implementing a substantial program, the work to move the advancements into routine practice can take significantly longer than the research itself. Unless plans are made – and followed – to continue the efforts over a long period of time, the eventual implementation is in jeopardy. While not all of the Lead State Team’s recommendations were followed to the letter, the issues were documented so that they could not be overlooked. Part of the development of the transition plan also included developing white papers describing the perceived future role of various groups, including the Superpave Centers and universities, in future implementation efforts. These white papers helped to lay the groundwork for the final transition plan and helped to show how existing groups could play an increasing role in the refinement and dissemination of the technology. (Some of the recommendations are addressed elsewhere in this report.) 5.4.2.4 Bottom Line So, were the Lead States effective and beneficial? The overall consensus seems to be yes. They did focus attention on Superpave and some of the issues with implementing it. Not all states/industry took advantage of the opportunities offered by the Lead States. Some felt they were not having problems and were leaders in their own right. Perhaps others were not aware of what the Lead States could do for them despite the attempts at publicizing the program. However, many states did make use of the resources provided by the Lead States. AASHTO and the Expert Task Groups listened to what the Lead States Team had to say and incorporated many of their recommendations into specifications and activities. The implementation surveys were widely distributed and referenced. Anecdotally, it was reported that non-technical agency administrators would sometimes see the surveys and question why their state was not implementing Superpave as rapidly as other states. Information from the Lead States Team was incorporated into many other groups’ communications (such as the Superpave Center newsletters, training materials, FOCUS, and other articles, etc.).

122 5.4.3 Superpave Centers One might think that the concept of Superpave Centers was driven in large part by the idea of implementing FHWA’s organizational ideas of regional and local management of SHRP and Superpave efforts. That was in the background, but one of the keys was the troublesome process of procuring SSTs and IDTs. “They were expensive, bulky, and required excessive training and knowledge in fundamental asphalt properties,” noted Ted Ferragut. “We had no manufacturers, no specifications, no test standards, and, really, no idea on tolerances for any of the equipment.” The concept as implemented was for FHWA to select manufacturers that could produce a limited number of SST and IDT devices, then deliver and install one at each Center. Ruggedness testing would be performed on the operation and output data of all the SST and IDT units. Under this phase, each of the Centers receiving delivery of the SST and IDT would conduct tests on a group of similar asphalt mixture specimens. The similarity of produced data on each SST and IDT was to be examined, the data produced imported into the Superpave software system and the similarity of output results examined. A team of experts, provided by the FHWA through the equipment manufacturer, would monitor the testing sequences, review the appropriateness of the data output of individual tests, aid each participant in the collection of data and incorporation of the data into the Superpave software, and analyze the results. After this initial evaluation phase, a more detailed equipment and procedural precision and bias analysis would be performed jointly with the Centers and the TFHRC. Finally, as needed, the Centers would be utilized to assist states in initial SPS-9 design. The FHWA team discussed this concept with the various committees, pointing out that was much more prudent to evaluate the devices first rather than to buy them for the DOTs. The idea was to establish a pyramid of acceptance: from one laboratory during the research phase to five laboratories during the evaluation phase. The risk of having a general buy of this equipment then finding it was not working as envisioned, plus the time it would have taken for a major buy, convinced all concerned that the one-to-five concept was prudent. This left the team with having to develop the regional concept and identify laboratories willing and able to set up programs to both evaluate this equipment and to become training grounds for DOTs and industry, going beyond the National Asphalt Training Center. It should also be mentioned that a catalyst behind the concept was Administrator Larson’s desire to promote Centers of Excellence around the country, including one at Penn State for Superpave. These ideas were eventually coupled into the Superpave Center concept. 5.4.3.1 Superpave Center Selection and Roles The first step was to divide the country into five regions, identify at least one good laboratory or university in each, and identify a champion who would make the Center concept work. In some regions the selection of a center location was fairly obvious and in others there was more competition. The Centers eventually selected included the Pennsylvania State University, Auburn University, Purdue University, the University of Texas at Austin and the University of Nevada at Reno. It was also agreed to help the University of California at Berkeley (UCB) to upgrade the equipment they used during the research phase, but not to call it a Center. (UCB did partner with the Center at Reno and worked with the other Centers as well.) The rationale behind selection of these particular centers in 1995 included:

123 1) PennDOT. Penn State was selected at the suggestion of Administrator Larson and with Dr. Dave Anderson still at the University. This Center was to serve the northeast states and work with the Northeast Asphalt User-Producer Group. 2) Indiana DOT. Purdue University was selected with Don Lucas, INDOT, in mind. He had championed the Superpave concept and was willing to make it happen at Purdue. This Center was to work with the North Central Asphalt User-Producer Group. 3) Auburn University was tied to the National Center for Asphalt Technology, under the guidance of NAPA. Their involvement was intended to give the industry a voice. This Center served the southeast U.S. and worked with the Southeast Asphalt User-Producer Group. 4) The University of Texas was selected with Tom Kennedy in mind as well as Bob McGennis. Kennedy managed the research team that developed Superpave and McGennis had substantial early Superpave experience. Principal funding of this Center was provided by the Texas DOT and for the period from 1995 to 1998, this Center played a significant role in the implementation of Superpave. This Center was to serve the southwestern states and Rocky Mountain User-Producer Groups. 5) University of Nevada – Reno was chosen with Jon Epps in mind. It was intended to serve the Pacific Coast and Rocky Mountain States User-Producer Groups. University policies made it difficult for Epps and his team to participate in outreach activities such as teaching NHI courses. In addition, the West Coast states were generally not very enthusiastic about Superpave, so they did not call on UNR for much assistance. All these factors contributed to a difficult road for the Western Superpave Center to fully materialize as a regional Center. Ultimately, the overall mission of the Superpave Centers was to assist the states and industry in each region with Superpave implementation. The common goals included providing technical leadership on Superpave, evaluating the Superpave equipment and test protocols, assisting with testing materials, and providing training. The specific goals of each Center included other tasks or different emphases to best serve their regions. Flexibility was built into the Center concept to allow the Centers to best serve the needs of their regions. FHWA provided test equipment and start-up funding for each Center beginning in 1995. The long-term plan for the Centers was for them to become self-supporting. FHWA would pay for specific project work, but each Center was expected to come up with operating and administrative plans and funds. Three of the Centers – in the Northeast, Southeast, and North Central regions – were funded through pooled-fund arrangements. The other Centers were never able to formulate a business plan with buy-in from the surrounding states. The Texas DOT generously funded the Center in Austin and encouraged the participation of the surrounding states. The high level of TxDOT funding, however, seemed to “brand” the Southeastern Superpave Center as a “Texas Center.” So although the Center staff provided training and other services to the surrounding states, those states did not feel compelled to join in as strong financial partners. The Western Superpave Center in Nevada struggled in part because of the initial reluctance of the states in the West to fully embrace Superpave. Administrative hassles with the university also hampered some of their activities. In short, the Centers that involved the surrounding states fully from the beginning were generally more successful in the long run. This

124 is not to say the other Centers were not successful – they all were in their own ways – but the Centers that had strong regional support also had greater longevity and visibility. Each Center developed its own strengths in response to the needs of its region. The Southeast Superpave Center, for example, developed a strong regional research program where two or three high-priority projects of regional interest were completed each year. The Northeast Center of Excellence for Pavement Technology, as the Northeastern Center is named, was (and remains) heavily involved in training and certification for PennDOT and developed a binder technician certification program. The North Central Superpave Center was (and is) active in training, technology transfer and research on state, regional and national levels. The Western Center was active in national research, particularly at WesTrack. The South Central Superpave Center was heavily involved in training and technical services, including evaluating new models of Superpave Gyratory Compactors, conducting Superpave mix designs for various state DOTs, and managing evaluations of Superpave mix test equipment. Even among the Centers that established pooled-fund arrangements, however, there were differences in how the funds were allocated. The Southeast Center, for example, essentially set up individual state accounts and a price list; states could choose what tasks to fund. The North Central Center, on the other hand, put all the state funds together to fund certain general activities considered essential for the long-term operation of the Center (so-called base funding). While each Center was eventually operated differently, there were commonalities. All were involved, in one way or another, with training. All the Centers also had an advisory group consisting of representatives of the various states and, usually, industry. Each Center was also involved in ruggedness testing, research and communication. Training was a major activity for the Superpave Centers in the early years. Eventually thousands of people received training from the Centers. Courses ranged from two-hour management overviews of Superpave through half-day sessions on the gyratory compactor to intensive, week to two-week long, hands-on binder testing and mix design courses. Participants in the courses included agency and industry personnel. While most of the agency personnel were from state highway agencies, other agencies were represented as well, including cities and counties, the FHWA, the Federal Aviation Administration and others. Industry trainees included hot-mix contractors, material suppliers, equipment manufacturers, consultants, industry association staff and others. All of the Centers (except for the Western Center) taught the National Highway Institute Superpave courses. Initially, the Centers coordinated their activities quite extensively. Meetings among the Center staffs occurred roughly every six months at one of the Centers (including the University of California at Berkeley). (Figure 41 shows the primary representatives of the five Superpave Centers at a meeting at the Asphalt Institute in about 1996.) Through these meetings, the Centers developed a rapport and shared their growing pains. Since these labs were among the very first to use some of the new, complicated equipment, there were numerous equipment and testing issues to resolve. These meetings also gave staff members a chance to see how each Center was set up, share experiences with the equipment and test protocols, and make plans for future collaborative work. Representatives from the Asphalt Institute (NATC) and FHWA also participated in these meetings. Occasionally others, such as the equipment manufacturers, attended as well. The Centers worked together in 1998 to develop a joint proposal to FHWA to develop a uniform, national hot-mix asphalt training and certification program and another to document and communicate Superpave information. FHWA funding constraints eventually precluded further development of those concepts.

125 Figure 41 Principals of the Five Superpave Centers meeting at the Asphalt Institute, circa 1996. (L to R, David Anderson, Northeastern; Jon Epps, Western; Rebecca McDaniel, North Central; Ray Brown, Southeastern; Bob McGennis, South Central) The Centers began cooperating in the summer of 1998 on the publication of joint newsletters as one means to ensure communication to a wide audience, some 6000 strong, about the evolution of the technology. The inside pages of these newsletters contained articles on issues of national interest and the outer pages were customized for each region. The design template for each region was the same with different colors reflecting the different parts of the country. The North Central Superpave Center took the lead on editing, designing and printing the newsletters while all the Centers shared in writing the articles. Eventually most Centers dropped out of the newsletter as funding became less certain or the Centers became less active. As of 2011, only two Centers are still collaborating on a joint newsletter, which is distributed to about three thousand people. Printed newsletters are being phased out and an electronic version is gaining in popularity. The internet was also used extensively for communication from the Superpave Centers. All of the Centers developed a website to highlight the particular features and activities of their Center. In addition, the South Central Superpave Center set up a newsgroup to facilitate the sharing of information between the subscribers. Established in December 1996, the newsgroup had over 250 subscribers by December 1998. One of the key missions of the Superpave Centers from their inception was to evaluate new pieces of equipment and associated test protocols. The Centers participated early on in the ruggedness evaluation of the Superpave gyratory, Superpave Shear Tester and Indirect Tensile Tester. Equipment and test protocol evaluations continue to this day as the Centers work on dynamic modulus testing, binder direct tension testing, the Asphalt Binder Cracking Device (ABCD) and more.

126 A 1997 AASHTO resolution (22) aimed to strengthen the support for the regional Centers. Citing the need for regional ownership of the Centers, the resolution encouraged financial participation by the states in their regional Center as well as state participation in the steering committees and supplying loaned staff to work at the Centers. The resolution also noted that FHWA had authorized the states to use 100% State Planning and Research SP&R) funds for their contribution. The level of funding support required was to be established by the individual regional steering committees. 5.4.4 TRB/NCHRP Despite the fact that FHWA took the lead role in the implementation phase of Superpave, TRB was not out of the picture, by any means. TRB was deeply involved in the research needed to complete and refine the system through its National Cooperative Highway Research Program (NCHRP). TRB played a vital role later in the implementation phase when the severe budget cuts of TEA-21 curtailed much of the FHWA-funded work. One of the key steps taken to deal with the impacts of TEA-21 was TRB’s co-sponsorship of the TRB Superpave Committee, along with FHWA and AASHTO, which was tasked with overseeing the implementation efforts. The TRB Superpave Committee will be discussed in Section 5.5.2. This section further outlines the key research activities at TRB/NCHRP. 5.4.4.1 Post-SHRP Asphalt Studies As with any major research initiative, along with accomplishments, new needs and opportunities emerged as SHRP neared completion. Recognizing the potential benefit of supplementing the completed research, AAHTO’s Standing Committee on Research (SCOR) recommended and approved NCHRP Project 20-35, Plan for SHRP Follow-Up Studies (29), as part of the NCHRP FY 1994 program. The project objective was to identify and prioritize research and development activities that should be pursued following the completion of SHRP, to build on completed research and help facilitate the use of SHRP findings. Jon Epps and Peter Sebaaly of the University of Nevada Reno led the effort for the asphalt component of this project. They reviewed SHRP publications and communicated directly with individuals involved in the conduct, surveillance, management and implementation of its findings. Epps and Sebaaly identified 32 potential projects and provided detailed problem statements and research objectives. The next step involved the participation of 20 individuals representing various sectors of the highway community in the review and evaluation of the 32 prospective problem statements. As a result of a two-day workshop held in June 1994, the group reached a consensus on six high-priority research projects. The following, in descending order of priority, is a ranking of the projects (29): 1) Refinement of SHRP Gyratory Compaction Technique 2) Applicability of SHRP Binder Tests and Superpave to Mixes Containing Modified Asphalt Binders 3) Adaption of SHRP Binder Tests and Specifications to Recycled Mix Design 4) Aging of Asphalt Binders and Mixes 5) Validation of Superpave Pavement Temperature Models 6) Evaluation of Water Sensitivity Tests

127 For each of the high-priority research projects, the group provided details of the problem, proposed research, potential benefit to highway agencies, as well as estimates of funding and time required to conduct the research. In addition to the high-priority research needs, the group identified and classified as highly important an additional research project entitled Refinement of Binder and Mix Tests, Specifications and Models, with funding to be provided by the FHWA. Finally, the group expressed support for other FHWA and NCHRP work underway or proposed, i.e., Superpave mix models and NCHRP Project 9-7, Field Procedures and Equipment to Implement SHRP Asphalt Specifications. Since 1993, 45 NCHRP projects have been funded in the bituminous area, 25 of which directly addressed some “follow-up” element of Superpave. Total NCHRP project funding in the bituminous area between 1993 and 2010 was $26.8 million, 60 percent of which (~ $16.1 million) was directed to Superpave follow-up studies. As is evident from the preceding, considerable funding has been directed toward the enhancement of Superpave. This does not include the considerable individual SHA efforts, i.e., work undertaken through the SPR (State Planning and Research) program. The significant post- SHRP research funding on Superpave is instructive. It is indicative of the broad scope and overly ambitious objective – conducting product-oriented research to facilitate the development of a readily-implementable solution to complex material behavior within a rigid time frame. The follow-up research was intended to address:  the topics ignored or inadequately addressed (e.g., physical/mechanical properties of aggregates, construction practices);  interesting/promising paths not taken (e.g., computerized tomography, acoustic emission)  refinement, procurement and manufacture of equipment prototypes (e.g., BBR, gyratory) 5.4.5 User-Producer Groups As implementation grew in importance towards the end of the research phase, thoughts were turning towards possible mechanisms to facilitate implementation. Tom Kennedy is widely credited with coming up with the idea of regional User-Producer Groups. Kennedy was very familiar with the Pacific Coast Conference on Asphalt Specifications (PCCAS), which had been formed in 1956 to standardize asphalt grades in states in the far West (Alaska, Arizona, California, Hawaii, Nevada, Oregon and Washington). Through committee and regular meetings, the group had encouraged the adoption of standardized specifications for various asphalt products across the region. Kennedy used the PCCAS model to encourage the formation of four similar groups across the country. The concept was to provide a forum where representatives of agencies and industry could work together to ease the growing pains associated with implementing a new technology. The North Central Asphalt User-Producer Group will be used as an example to illustrate how these groups came to be. Each region is a little different, but, like the regional Superpave Centers, have some commonalities. In the summer of 1991, Tom Kennedy travelled to West Lafayette, Indiana, and met with a core group of people to discuss the formation and possible activities of a regional user-

128 producer group in the Midwest. The invitees included representatives of the Indiana, Iowa and Minnesota DOTs and asphalt paving associations plus Dick Ingberg, the SHRP Regional contractor. (An earlier meeting between Kennedy, Ingberg, Gerry Huber, and Dave Holt and Richard Wolters from the Minnesota Asphalt Pavement Association in Minneapolis led up to this meeting.) Kennedy updated the group on the current status of the mix design and analysis system and the binder specification. He also outlined his vision of proposed activities:  Catalog asphalts and aggregates used in the region along with performance;  Identify problems experienced in specific areas and relate them to environmental conditions and/or the material properties identified in #1;  Evaluate the mix design procedure and aggregate requirements;  Evaluate the binder tests and specification limits (when available);  Evaluate the mixture tests and specification limits (when available, interestingly, Kennedy noted this activity “may have to be delayed”);  Sample test sections and monitor performance; and  Build test sections to evaluate specific variables (in consultation with A-001). Following this pre-planning meeting, the participants continued to discuss the potential for a regional group. By the end of 1991, they had formulated a plan and held an initial meeting in Chicago in September 1991. The group embraced the concept of forging a closer working relationship between the agencies and industry in the region. The group aimed to create a climate for change throughout the region. The overall mission of the North Central Asphalt User- Producer Group was to “improve the quality and cost-effectiveness of asphalt pavement.” In order to accomplish that one of their most immediate roles was to discuss, evaluate and implement the results of the SHRP Asphalt Research Program. In fact, SHRP implementation was the major focus of the group for many years. Later QA and other issues were added to the plate. Now that Superpave is the design procedure for hot-mix asphalt in the region, the group continues meeting annually to share information on other asphalt-related issues such as the MEPDG, pavement warranties, warm mix, performance-related specifications, intelligent compaction and more. States and provinces in the Midwest and Canada were invited to join. After some jockeying around, the states corresponding mainly to the AASHTO region joined forces. These included Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, Ohio and Wisconsin with limited participation from the Dakotas, Manitoba and Saskatchewan. The group was and is managed by a Management Committee consisting of one state and one industry representative from each state in the region. A subset of Management Committee members comprises the Executive Committee. In the early years, task forces addressed binder, aggregate and mixture issues. Regional meetings were held once or twice a year, often in conjunction with a workshop on binder, mixture or other issues. Meeting attendees included chief engineers and upper management, asphalt engineers and middle management, and technicians and mix designers. One valuable feature of the NCAUPG meetings in the formative years was a one-day meeting for technicians. Though sometimes portrayed as “gripe sessions” in the early years, the meetings gave the folks who were down in the trenches working with the new equipment and test protocols a chance to share experiences, successes and failures. These meetings were instrumental in getting the technicians up to speed.

129 To this day, the meetings are generally structured to provide information about what is happening in the asphalt arena on the national, regional and state levels. These meetings are one of a very few opportunities to learn about regional issues and solutions. Travel restrictions and the state of the economy are hindering broad participation in the UPGs in many cases, however, the efforts to bring the regions together are continuing and the use of technology (webcasting, virtual meetings, etc.) is being explored to facilitate continued communication. This group was definitely a key in obtaining the upper level management support that was necessary for implementation (though the AASHTO chief engineers meetings were also instrumental). The NCAUPG also worked between meetings to further implementation efforts. Binder round robins were performed to examine testing variability, which was quite high when technicians were on the steep part of the learning curve. A group of binder suppliers and DOT personnel put together an asphalt supplier certification plan that eventually formed the basis for AASHTO PP 26 (now R 26), the “Standard Practice for Certifying Suppliers of Performance- Graded Asphalt Binder.” A subset of states from the region began meeting in conjunction with the regional meeting to form the Combined State Binder Group (CSBG). This group of five (originally six) states cooperatively shares responsibilities for binder acceptance testing. While the group had a number of successes and has continued in existence because of its intrinsic value, not every attempt met with success. For example, the group talked for years about standardizing mixture test procedures to facilitate reciprocity of certifications across state lines. Recommendations for reducing the number of variants of AASHTO test methods were developed and forwarded to the AASHTO Subcommittee on Materials for consideration. Despite many efforts in this regard, the standardization has not yet been realized on a regional basis, though there is some cooperation between individual states. The North Central Asphalt User-Producer Group formation and activity was presented here as one example of what the UPGs accomplished. Each regional group was set up a little differently and tackled somewhat different issues, but all remain successful to this day, in different ways. It is, perhaps, a little ironic that the PCCAS was the model for the formation of the other regional UPGs but may have been the least successful in facilitating implementation of the Superpave asphalt products (though they have certainly been successful in other ways and states in the region are now coming on board). 5.4.5.1 Benefits and Expansion of the UPG Concept The User-Producer Groups were, for the most part, very effective at establishing partnerships between agencies and industry within the regions, providing a forum for the exchange of information and facilitating the implementation of the new test procedures and specifications from the SHRP Asphalt Research Program. The fact that all of these groups are still meeting regularly, despite the current economy and difficulties in obtaining out of state travel approval for agency personnel, is evidence of their perceived value. In the early days of the UPGs, travel for state and industry personnel, though not a foregone conclusion, was not as difficult as it is today. Nonetheless, for many people travel to a meeting within their region was easier to arrange than travel to a national meeting. The regional meetings gave these people who could not attend national meetings a place to meet and share information. They were (and are) an excellent venue for presenting information from a national level and making it relevant to the region.

130 A National Asphalt User-Producer Group was also active for several years. Its first meeting was held in Minneapolis in August 1993. Eventually the national group was superseded by the Expert Task Groups and was essentially, though perhaps not officially, disbanded. Many states also formed their own individual User-Producer Groups. This brought the concept down to an even lower level and allowed more people to participate in the partnerships and information exchange. These are generally no longer active as PG binders have become the routine and issues are generally few and far between. FHWA was instrumental in supporting the User-Producer Groups and helping them to be, in general, very successful. FHWA was very accommodating about sending speakers to the UPGs and providing whatever support they could for the groups. 5.4.6 Technical Working Group and Expert Task Groups Expert Task Groups were used during the SHRP Program to provide technical review and guidance of the SHRP research. There were a number of ETGs formed; generally they were aligned with specific research contracts or were formed for a specific purpose. At the end of SHRP, FHWA took on the responsibility for Superpave implementation. FHWA had used ETGs in the past as a method of including industry input to FHWA activities. For example, the FHWA sponsored a Volumetric Properties ETG chaired by John D’Angelo during the SHRP Program to gather information from the asphalt community regarding volumetric properties. This information was provided to the A001 contract and became a significant input into the Delphi process that was used to determine volumetric properties in Superpave. A year before SHRP was scheduled to end, a meeting was held at the Old Colony Inn in Alexandria, Virginia, to make plans for completion of the research phase and ramping up of the implementation effort. All, or nearly all, of the states were represented at the meeting. Ted Ferragut of the FHWA remembers the atmosphere being somewhat tense in that state DOTs were concerned that FHWA would mandate use of Superpave. At the meeting, plans were made for test method standardization through AASHTO, and a pooled fund was organized for the purchase of new asphalt binder and mixture equipment. Also at that meeting, an Asphalt Technical Working Group (TWG) was formed. The TWG provided guidance for implementation of the SHRP Asphalt products. The first meeting of the TWG occurred in 1993, and at that meeting Expert Task Groups were formed to provide more detailed technical guidance for adoption of Superpave. Initially two ETGs were formed, Asphalt Binder and Asphalt Mixture. These ETGs would be the responsibility of FHWA and would have representation from FHWA, state DOTs and industry. The ETGs were to provide advice on implementation of including test methods, equipment, specifications, etc. At the first meeting in Alexandria and at the first TWG meeting that followed, Ted Ferragut remembers industry reluctance about adoption of the new specifications. The asphalt binder industry was relatively accepting of the new technology. The hot-mix asphalt industry was somewhat more reluctant. It was clear then that the hot-mix industry was not on board. The reaction to the need for new equipment was strongly negative. Generally those contractors from states that were working in QA specifications and had responsibility for their own mix designs were more upset than those who came from traditional states, where the DOT did the designs and quality control.

131 Many of these QA contractors had recently built laboratories and now were being asked to discard their Marshall hammers, which cost $1200, and replace them with a gyratory compactor, estimated to cost $16,000. And since there was generally one laboratory at each hot-mix plant, the cost of implementation just for Level 1 mix design was considered excessive. The mantra of the industry became “One size does not fit all”. The position being that Superpave was not ready for implementation. Extensive additional research was needed before Level 1 (volumetric mix design) could be implemented. Over the course of several meetings there was in-depth discussion of equipment cost, the test protocols and the time to prepare samples. The asphalt binder industry did not react as strongly against the new specifications as the hot-mix asphalt industry. One of the historic issues that face asphalt binder suppliers was the proliferation of specifications. Generally asphalt binder suppliers dealt with a larger market area than a hot-mix asphalt contractor, and having different specifications for different agencies caused additional costs. The Superpave binder specifications offered the possibility of a standard specification for all agencies, something the asphalt binder industry had been working toward for some years. As a result, although there were issues with the test equipment and test methods, as well as longer testing times, the asphalt binder industry worked toward resolution of the issues. On the other hand, the hot-mix asphalt industry consisted of a large number of smaller companies that generally worked within a smaller geographic area. As the Superpave binder specification had issues, the Superpave asphalt mixture specifications also had issues with test equipment and test methods. In addition, the specifications had more restrictive requirements for aggregate properties than had generally been used. This was particularly true in areas that were dependent on gravel as the main source of aggregates. Depending on the primary source of aggregates and the current mix design specifications in a given area, the net effect of adopting Superpave mixture specifications was that industry would at best be not severely impacted by the new specification. In many areas there would be an impact on the cost of producing HMA because of changes to aggregates or asphalt binder content. As a result, many HMA contractors argued that the new specifications were not needed. Current practice was producing good performing pavements, and there was no need for change. The Asphalt Mixture ETG provided a forum for dialogue. Over the course of ten to fifteen years, many issues were aired and changes implemented. Table 16 lists meetings of the Asphalt Mixture ETG that have occurred to date. The Asphalt Mixture ETG provided input that led to research products and provided guidance regarding Superpave specification changes. Such input lead to the following NCHRP research topics:  QC/QA with Superpave gyratory compactor  Refinement of design gyrations  Incorporation of reclaimed asphalt pavement  Investigation of the restricted zone  Investigation of VMA as a mix design parameter and setting of limits.  Precision statements on gyratory compactor  Simple performance test  Investigation of laboratory aging method Table 16 Asphalt Mixture Expert Task Group Meetings

132 Place Date 1 Atlanta, GA Jun 24 & 25, 1993 2 St Paul, MN May 26 & 27, 1994 3 Lexington, KY (Asphalt Institute) Aug 24 & 25, 1994 4 Austin, TX Feb 7 & 8, 1995 5 Reno, NV May 16 & 17, 1995 6 Baltimore, MD Sep 19 & 20, 1995 7 Phoenix, AZ Mar 4 & 5, 1996 8 Seattle, WA Sep 10 & 11, 1996 9 San Antonio, TX Mar 4 & 5, 1997 10 Colorado Springs, CO Sep 22 & 23, 1997 11 Orlando, FL Mar 10 & 11, 1998 12 Baltimore, MD Sep 22 & 23, 1998 13 Phoenix, AZ Mar 18 & 19, 1999 14 Washington, DC Sep 21 & 22, 1999 15 Washington, DC Mar 28 & 29, 2000 16 Indianapolis, IN Sep 11 & 12, 2000 17 Phoenix, AZ Apr 3 & 4, 2001 18 Washington, DC Aug 28 & 29, 2001 19 Denver, CO Feb 20 & 21, 2002 20 Minneapolis, MN Aug 28 & 29, 2002 21 Las Vegas, NV Sep 16, 17 & 18, 2003 22 Washington, DC Feb 11, 12 & 13, 2004 23 Washington, DC Sep 27 & 28, 2004 24 Madison, WI Jul 20 & 21, 2005 25 Denver, CO May 11 & 12, 2006 26 Crystal City, VA Sep 25 & 26, 2006 27 Denver, CO Jul 24 & 25, 2007 28 Tampa, FL Feb 25 & 26, 2008 29 Irvine, CA (Beckman Center) Feb 26 & 27, 2009 30 San Antonio, TX Sep 14 & 15, 2009 31 Irvine, CA (Beckman Center) Feb 22 & 23, 2010 32 Madison, WI Sep 21 & 22, 2010 33 Phoenix, AZ Mar 17 & 18, 2011 An example of the role of the ETG is illustrated by the deliberations on design gyrations that occurred at the meeting held in September 1998 at Baltimore. NCHRP Project 9-9, being done by the National Center for Asphalt Pavements, was to investigate current design gyration values and make recommendations for change. The Asphalt Institute, working under the National Asphalt Training Center, reported the results of a study done for FHWA on the effect of design gyrations on mixture properties. Results of the two research projects were presented to the ETG. After discussion, the ETG recommended that Ray Brown and Mike Anderson, as principal investigators of the two projects, should have dinner together and return the next day with a joint recommendation, which they did. The ETG agreed with the recommendation, and it was forwarded to the AASHTO Subcommittee on Materials for balloting. It passed on the first ballot.

133 Similarly, the Asphalt Binder ETG dealt with issues regarding the asphalt binder specification. For example, the original SHRP research recommended the use of direct tension testing for the grading of modified asphalt binders. The SHRP researchers delivered a test method and proposed specification criteria. The ETG wrestled with testing issues and after several years decided that test variability could not be reduced sufficiently. A new test method, Multiple Stress Creep Recovery (MSCR) was devised and proposed to the ETG. Ultimately the Binder ETG concurred with the research and forwarded a recommendation to the AASHTO Subcommittee on Materials The role and purpose of the Asphalt Mixture and Asphalt Binder ETGs remain as valid today as in 1993 when they were first formed. These two ETGs continue to meet and review information and provide guidance for research needed and specification changes for HMA to the AASHTO Subcommittee on Materials 5.4.7 Asphalt Institute As implementation plans developed in 1992 it became apparent that the implementation would exceed the personnel resources of FHWA, and a decision was made to develop a National Asphalt Training Center, as discussed in Section 5.2.2.4. The role of this Center would be to develop training courses and manuals necessary to disseminate information about the new specifications and provide state DOTs with sufficient information to implement Superpave within their state. Also, as the SHRP Program was drawing to a close, it became apparent that many implementation questions required additional investigation. These issues included:  What is the correct laboratory compaction effort?  Can mix be designed with a gyratory and controlled with a Marshall hammer?  Can crumb rubber modified asphalt binders be tested for PG grade?  Are flat and elongated specifications too restrictive? Too permissive?  What about fine aggregate angularity? There were a host of questions coming from state DOTs, the asphalt binder industry and the hot- mix contractor industry. A mechanism was needed to address such questions if implementation had a hope of succeeding. This mechanism was addressed, in part, through the contracts with the Asphalt Institute. In September 1992, FHWA had awarded a three- year contract for the NATC to the Asphalt Institute. A follow-up five-year contract, NATC II, was awarded in September 1995. Training was a large portion of their work. The first task was to develop training materials and manuals. Hands-on training was required for the first wave of DOT engineers and lab technicians. Courses in binder testing and mix design were taught beginning in July 1993 at the Asphalt Institute laboratories in Lexington, Kentucky. By the fall of 1996, 18 binder and 18 mix courses had been taught, training over 700 engineers and technicians from agencies, industry, FHWA and universities. Pilot one- and two-week courses on the mix analysis system were also developed and presented under NATC II. The Institute continued to offer the binder and mix training after the second contract expired (on a fee basis). In the early days of Superpave implementation, there were numerous wildfires of opinion that ran through the industry. Such controversies included:

134 • Tender zone – mix could not be compacted because it is tender. • VMA – Superpave mixtures could not be designed with our aggregates to meet VMA requirements. • Gyratory Compactors – different compactors produce different air void results for the same mix. • Binder Contents – some people felt mixes did not have enough asphalt binder in them. • Compaction – difficulties in achieving field compaction were thought to result in high permeability with these mixes. The Asphalt Institute helped develop information that defused many of these controversies or provided information for making changes to the specifications. Such areas included: • Reducing the number of traffic levels from seven to five. • Removing the summer temperature provision of the Ndesign table. • Changing the Ndesign table to the current levels. • Compacting specimens to Ndesign instead of N-max. • Changing short-term oven aging from 4 hours to 2 hours. • Vacuum degassing asphalt after PAV (Pressure Air Vessel) conditioning. • Refining the Rolling Thin Film Oven protocol regarding scraping of the bottles. • Developing protocols for Direct Tension testing of asphalt binders. • Refining the Bending Beam Rheometer protocols to establishing time zero. These and other issues required investigation, recommendation for change, and modification of manuals and training material. The Asphalt Institute was involved in Superpave-related activities from other sources as well as the NATC. They were involved in NCHRP Project 9-7, Field Procedures and Equipment to Implement SHRP Asphalt Specifications. This project had the combined goals of demonstrating how asphalt binder and hot-mix asphalt could be designed and produced under the new Superpave specification. By the end of the second NATC contract in September 2000, the implementation of Superpave was quite mature. Most states had adopted the Superpave binder specifications. Many had adopted the Superpave mixture specifications. The FHWA and the NATC worked in cooperation with AASHTO (especially the Subcommittee on Materials) and the AASHTO Lead State implementation effort. Together the stage was set for adoption of the results of Strategic Highway Research Program. 5.4.8 NAPA and the Construction Industry It is widely felt that the material suppliers and highway contractors did not play a large enough role during the research phase of Superpave. While there were various industry representatives on committees, industry was largely missing in the defining stages of the research. Those industry representatives who were involved were generally at the highest levels. The technical people from industry were brought in fairly late in the game when the products had largely been framed. Earlier and deeper industry involvement in the research phase, in retrospect, would probably have facilitated implementation later. Many felt that industry was going to have to implement a system that they had little hand in shaping. This, plus the general resistance humans have to change, created some serious

135 apprehension in the industry. There were inevitable cost impacts associated with implementing Superpave that industry would have to bear – and pass along to their customers. Thousands of people needed training, new equipment would have to be purchased and some long-standing procedures would likely need to be changed as well. It is easy to understand how those who had not been involved in the process would be reluctant to fully embrace the changes that were coming. On the other hand, there were many in the industry that recognized that change was necessary. The performance problems that had prompted the SHRP Asphalt Research in the first place had not been resolved on a national level. (There were some individual states that had investigated issues like premature rutting and had instituted their own changes in factors like crushed faces and gradations.) Left unchecked, these problems could seriously erode asphalt’s market share. While Superpave might not be perfect, it was seen as an improvement over what had been done in the past. In fact, industry did play a large role in the later stages of the research phase in forcing the shift from binder chemistry to mixture properties. Gerry Triplett, President of the Asphalt Institute had reportedly tried to point out to the SHRP Executive Committee the shortcomings of a binder chemistry approach. This was perceived by some in the states that the binder suppliers were defensive and trying to protect their interests. People like Charlie Potts, Roger Yarbrough and Campbell Crawford eventually helped bring about the change in emphasis by focusing on the importance of mix properties. The fragmentation of the asphalt industry also probably played a role in the attitudes towards SHRP. There was no single entity looking over and involved in the research. There was no coordinated industry involvement. Industry involvement was (and is to this day) usually voluntary and unfunded, so there must be a benefit to being involved to justify the time and expense required for participation. Today industry plays a larger role in the research process through the National Center for Asphalt Technology, participation in TRB committees and NCHRP projects panels, and other means. Industry was dealing with a number of other momentous changes around the same time SHRP implementation was building steam. Many states were moving towards quality control/quality assurance (QC/QA) type specifications. In fact, Superpave and QC/QA specifications were implemented simultaneously in several states. Industry representatives frankly state that the industry was not very technical at the time SHRP was initiated. They had been using “cookbooks” provided by the state specifications. The implementation of Superpave forced them to develop a deeper understanding of their products. Around the same time, states’ budgets began shrinking and experienced personnel were retiring. All these factors together led to industry becoming much more technically proficient than they had been before and in many cases more knowledgeable than the DOTs. When implementation became a real feature on the horizon, many in industry saw things that did not make sense to them. They had not been validated in the field. The pooled-fund equipment buy may have been helpful for the states, but industry as a whole did not have the equipment. When equipment became commercially available, it raised the awareness of the industry. Awareness was also raised through meetings like the TRB Annual Meeting, the Association of Asphalt Paving Technologists meeting and the user-producers groups. Those contractors whose personnel were able to participate in such meetings were better prepared to implement Superpave because they had gained some insights into what was coming. Companies

136 with a corporate vision to be leaders and innovators also had a leg up. Good relationships – partnerships – between agencies and industry also helped overcome the reluctance to change. There were also inevitable personality conflicts surrounding implementation. Many in industry saw FHWA as being heavy-handed, even dictatorial. Use of Superpave had not been officially mandated by FHWA, but sometimes it felt as if it was. More flexibility and an acknowledgement that there were problems that still needed to be addressed would also likely have helped facilitate implementation. Eventually FHWA seemed to loosen up and partner more with the end users to make adjustments in the system through the ETGs, working with the UPGs and other collaborative efforts. Another facet of the industry, besides material suppliers and contractors, was heavily involved in implementation – the equipment manufacturers. Without their efforts to produce the needed equipment, implementation would not have been possible. The first article procurement was challenging for some of the equipment manufacturers, especially the gyratory manufacturers. The equipment specification was put out for bid, then withdrawn when it was realized that the actual angle of the prototype gyratory used at the Asphalt Institute was not 1° as planned but was in fact 1.27°. Other changes in the equipment came along later in the implementation phase. The binder direct tension device had to be completely redesigned after the initial version had severe limitations; to this day direct tension is rarely used. Manufacturers had to seriously investigate the potential market for equipment before deciding to pursue manufacture. The volume of the market was very uncertain, especially since changes were being made in the system up to and beyond the end of the research phase. Construction equipment manufacturers also had to gear up since higher traffic level Superpave mixes required heavier pavers and higher efficiency rollers to compact and lay these mixes. They met the challenge and were a key element in contractors being able to produce Superpave pavements. Eventually industry in most states embraced Superpave technology. In fact, in some places, industry encouraged wider use of the technologies by the states as well as local agencies. Once they had invested in training and equipment, they preferred to use it and maintain one system, rather than a combination of old and new. Industry also participated in various efforts, like the development of the Approved Asphalt Supplier Certification procedure, in partnership with DOTs. 5.4.9 SPS-9 Projects As mentioned earlier (5.4.1.3), the AASHTO Task Force on SHRP Implementation supported the ongoing research under the Long-Term Pavement Performance program and was instrumental in urging AASHTO to step in to fund continued efforts when the FHWA discretionary funds that had supported LTPP (among other activities) were virtually eliminated under TEA-21. For Superpave, the main LTPP activity was the so-called SPS-9 experiment. The Specific Pavement Studies experiments within LTPP involved the construction of test sections with controlled variables designed to evaluate specific pavement features. This was in contrast to the General Pavement Studies (GPS) sections, which were existing pavements. The SPS-9 program was intended to monitor the performance of pavements constructed using the newly developed Superpave specifications. The first pilot SPS-9 sections were constructed in 1992 in Indiana, Wisconsin and Maryland before the research phase had officially ended. Additional pilot projects were constructed in Minnesota and Kansas in 1993. (Wisconsin

137 constructed a total of three pilot SPS-9 projects.) Each site consisted of multiple test sections to allow comparison of the existing state practice to Superpave. Additional sections could be added at the state’s request. The sites were monitored for rutting and other pavement distress and traffic levels. Later, additional SPS-9A sections were constructed to compare various binder grades and SPS-9B sites were constructed to evaluate various mix design parameters. The Asphalt Institute and some Superpave Centers assisted with mix design for many of these projects. Unfortunately, the budget cuts imposed by TEA-21 severely curtailed the monitoring of these sites under LTPP and few SPS-9A or 9B sites were constructed. The sites that were built, however, proved to be extremely beneficial in a number of ways. These experiments were closely watched in the early years. They showed that states could implement the new specifications and contractors could construct pavements using the new designs. They also provided data that was used to encourage further implementation. For example, one of the Wisconsin test sites provided mix design data that was used in the training materials prepared by the National Asphalt Training Center (5.4.7). These training resources were used not only by the Asphalt Institute but also by the Superpave Centers, state training organizations, universities and others. A 1995 paper presented at the Association of Asphalt Paving Technologists meeting in Portland, Oregon, reported on the design, construction and early performance of six of the seven pilot SPS-9 projects. There was great interest expressed by the AAPT audience in seeing factual data from the projects. Although the thorough, long-term performance evaluation initially envisioned through LTPP did not happen, the SPS-9 sites did show other states that the new Superpave material specifications and mix design requirements could be successfully implemented. States constructing these sites typically did internal follow-up to supplement the LTPP monitoring activities. (For example, as of 2011 Indiana is still following its SPS-9A project constructed in 1997.) The opportunity for focused nationwide evaluation of the field performance of Superpave mixes, however, was lost due to a lack of resources. 5.4.10 Universities A limited number of universities were involved in the SHRP Asphalt Research program and even fewer were selected to be Superpave Centers. While these universities were able to offer their students, especially graduate students, a chance to get involved in Superpave on the ground floor, the majority of engineering schools around the country had had little exposure to the program. If Superpave were to become the accepted method for selection of materials and design of mixes, the engineers of the future would need to develop familiarity with the technology. As the training grounds for these budding engineers, the faculties at the more than 200 engineering schools in the US (and beyond) needed to understand and teach Superpave technology. FHWA recognized the need to train undergraduate engineering students and sponsored the development of training materials for undergraduate and graduate level materials courses. These course materials were developed by NCAT and were distributed to Technology Transfer Centers in the states, state materials engineers, FHWA division offices, industry and the Superpave Centers on CDs. From there, the CDs have been widely distributed nationally and internationally. Superpave technology is now incorporated routinely in engineering and technical curricula.

138 Availability of Superpave testing equipment has also increased greatly since the implementation phase began. In some cases, this equipment has been provided by industry to ensure that engineers graduating from those schools have the opportunity to become familiar with the technology they will be expected to use in practice. Auburn University also started a popular professors training course at NCAT in 1994. It has been taught every year since. A less intensive course was provided by the North Central Superpave Center for Indiana universities with funding support from FHWA. Universities in most states have become increasingly involved in using Superpave technology in their teaching and research, as well as helping state DOTs provide training and certification for their employees and industry. So, from a limited number of schools involved in the SHRP asphalt research, the number of universities providing Superpave training and experience has increased dramatically over the last 18 years. Any reputable school with a curriculum involving asphalt is now instructing students in Superpave technology and, usually, providing lab experience with the tests and equipment. 5.4.11 Conferences and Workshops The number of conferences and workshops dedicated to various aspects of Superpave technology is indisputably large, but impossible to determine. Conferences have been held at all levels from international to national, regional, state-wide and local. They have been sponsored by individual agencies, industry groups (state paving associations, NAPA, the Asphalt Institute, International Center for Aggregates Research and many more), the Association of Asphalt Paving Technologists, the Superpave Centers, the User-Producer Groups, regions, FHWA, TRB and many others. Early on in the implementation process, however, a few national conferences were held that deserve particular mention for helping to spread the word about the status of Superpave implementation and its challenges. In particular a major conference was held in Reno, Nevada, from October 24 to 28, 1994, to hear the results of the SHRP research as well as implementation efforts. (A transcript is available as an electronic appendix (Appendix E) to this report.) By late 1993 and early 1994 final reports from the different asphalt research contracts were printed and became available to the asphalt community. Their sheer volume was overwhelming. The reports consumed about three feet of shelf space. It was clear that very few in the community could or would devote the time to digest them and extract the important information. This major conference was initiated by the Asphalt Technical Working Group and was funded by FHWA. The conference was sponsored by the FHWA, the Nevada Department of Transportation, AASHTO, TRB, the Asphalt Institute, NAPA and the International Society of Asphalt Pavements. Total attendance was 460 representing a broad cross section of the U.S. asphalt community and about 20 foreign countries. Sessions went from 8:00 am to 6:15 pm. On Wednesday evening four parallel tracks of supplementary sessions were held from 7:30 pm to 10:00 pm. From Monday noon until the end of Wednesday the researchers presented results of their research program. Thursday was devoted to implementation issues from the point of view of FHWA, state DOTs, asphalt binder suppliers, contractors and AASHTO (specifications). Friday morning was devoted to two case studies from the points of view of the mix designer and the state DOT.

139 Continuing in 1996 until 2000 biannual workshops were sponsored by FHWA, with various co-sponsors including the Asphalt Institute, TRB, state DOTs, the Superpave Centers and other industry groups. The themes and locations of the workshops are shown below. • Open House on Superpave 2000, August 21-22, 1996, Indianapolis • Superpave: Today and Tomorrow, April 21-23, 1998, St Louis • Superpave: Building Roads for the 21st Century, April 10-12, 2000, Denver The objective of the Superpave 2000 Open House was to demonstrate how states were implementing Superpave in order to share experiences and encourage other states to adopt the new technology by the year 2000. Indiana was the host state for the conference because of its aggressive and largely successful implementation program. (INDOT credited part of its success to the fact that it had members on the Binder ETG and Asphalt TWG, in addition to Chief Engineer Don Lucas being involved in the SHRP Executive Committee.) The workshop included site visits to paving projects (on county roads, showing that Superpave was not just for high volume roads only) and the North Central Superpave Center. Presentations described the current national status of binder and mix implementation, WesTrack performance, the industry perspective on implementation, warranties and more. Representatives from Florida, Maryland, Arizona and Indiana also reported on the progress of implementation in their states. Superpave: Today and Tomorrow was intended to develop better understanding of the Superpave system, research and implementation efforts ongoing in 1998, and changes being made to the system. The conference was held in St. Louis, Missouri, in part because of the important role Joe Mickes, MoDOT’s Chief Engineer, played as chairman of the TRB-SHRP Committee and the involvement of MoDOT in the Lead State Teams. One important element of this conference was the presence of information booths and vendors who displayed the newest equipment. In the opening session, Don Steinke, chief of the Highway Operations Division of FHWA, gave a presentation where he openly acknowledged some of the problems that had been encountered by states implementing the new technology and approaches to resolving those problems. First he cited a number of successes with implementation, such as the fact that most states had implemented the binder specification and that local agencies (including Albuquerque, NM; Los Angeles County, CA; St. Louis County, MO; and Maricopa County, AZ) were using Superpave. Then he addressed the problems – permeability in Florida, flushing in Indiana and rutting at WesTrack. Steinke noted that the Florida DOT had worked with FHWA to solve the problem of increased permeability in Superpave mixtures by increasing the lift thickness to four times the nominal maximum aggregate size to allow room for the additional compaction necessary. The flushing of several miles of newly paved interstate in Indiana had generated a lot of talk about the failure of Superpave. Investigation into the cause, though, revealed a number of factors not related to Superpave – most importantly several days of rain and inadequate drying of the aggregates during mix production. Steinke commented that both Florida and Indiana remained fully committed to implementing Superpave despite the problems they had encountered. Lastly, Steinke acknowledged that coarse-graded Superpave mixes at WesTrack had shown early rutting and he reported on the preliminary findings and recommendations of the forensics team (summarized in 5.6.4.3). Much of the rest of the conference focused on contractors and industry and the issues they were facing. Problems and concerns were raised and, when possible, resolutions were

140 offered. Sessions dealt with mix design, material selection, construction, and performance testing and modeling. Notably, Ron Sines from the New York State DOT and Chuck Deahl of Compaction America offered suggestions for dealing with compaction problems in the field. Dale Decker reported on a survey of twenty contractors who had experience working with Superpave mixtures. He noted that while the performance had been good to date, there had been some problems with production and placement. NAPA had produced a document offering Superpave Construction Guidelines to help deal with these issues. The survey showed that existing binder and aggregate suppliers were able to provide materials meeting the new requirements. At the mix design stage, achieving the VMA was challenging for about half those surveyed. For most contractors, production of the mixes was “business as usual,” but field compaction was more difficult, especially with higher compaction requirements for some mixes to eliminate permeability issues. Speakers from both the asphalt refining and aggregate industry expressed general support for the implementation of Superpave technology but noted the large investment that would be required in some cases to produce the materials. Refiners had challenges to face in producing different grades of binder at the same terminal and were finding they needed more tanks to store the different grades separately. Gene E. Chew, from American International Refinery, stated that the Asphalt Institute and its member companies were “absolutely committed” to the implementation. Mark Towe of the National Stone Association also expressed support “provided that current concerns and issues can be resolved satisfactorily.” He commented on the large investments some aggregate producers would potentially need to purchase different crushers and other equipment to meet the shape and gradation requirements. The last of these biennial conferences was held in Denver, Colorado, in April 2000. Superpave: Building Roads for the 21st Century highlighted the changes that had been made in the AASHTO specifications for Superpave. It also included discussions of ongoing industry issues. Kim Snyder, then chairman of the National Stone Association, reported on research that was sponsored by the NSA through the International Center for Aggregates Research (ICAR) to address some of the issues of concern that Mark Towe had mentioned at the previous conference. Projects focused on the requirements for flat and elongated particles, fine aggregate angularity, the restricted zone and VMA. Sessions at this conference were centered on selecting materials, design and production, construction, and performance and the future. Materials suppliers, contractors, DOT personnel and researchers shared their experiences with QC/QA, mix design, laydown and compaction and more. Some of the changes that had been implemented by this point in time included reduction in the number of design and temperature levels, establishment of a 20-year design life, reduction in the design compaction level for mixtures deeper in the pavement, and changes in the binder and mixture conditioning protocols. The conference showed that there were still items that needed attention and refinement, but that Superpave mixtures could be produced and were performing well. The message was that work was underway to continue the refinement of the system in the future but that the framework was sound and workable. Countless other conferences, workshops and open houses at all levels and for a wide range of audiences helped to spread the word that implementing a new system would take work but that it could be done. Experiences were shared amongst the agencies, industry and researchers to help the process along.

141 5.5 IMPLEMENTATION AT RISK – THE TEA-21 YEARS In 1999, the Superpave world was about to change and very few people saw it coming. It started with the Transportation Equity Act for the 21st Century (TEA-21). That legislation clearly restructured highway research funding in a way that nobody had anticipated. TEA-21 abruptly stopped discretionary funding for the SHRP Implementation Program. Why? Many reasons surfaced, but most would attribute it to the stakeholders possibly getting too complacent about the funding and failing to show Congress the benefits that had already accrued. AASHTO and FHWA partnered immediately after passage of the bill to develop a “Save SHRP” program. Everyone agreed that the SHRP products, especially from Superpave and LTPP, were nowhere near complete. Without support, Superpave implementation could grind to a halt immediately just as many of the states were coming to grips with the binder and mix specifications and making changes to their practices. 5.5.1 Background The Federal-aid Highway Program has historically included discretionary funding for research and technology transfer by the FHWA to support innovation among state and municipal departments of transportation and the private sector of the highway community. The passage of the Transportation Equity Act significantly changed the discretionary funding levels and shifted responsibilities for program definition and management. With the dramatic reduction in FHWA discretionary funds, many continuing research programs of national importance – Superpave among them – were threatened with delay or cancellation (30). Recognizing the seriousness of the situation, AASHTO committees and task forces developed contingency plans for continuing research and implementation, especially for those SHRP research findings currently being implemented. The AASHTO Board of Directors, after carefully considering these contingency plans, passed resolution AR-5-98, on November 8, 1998 (23). Key provisions of the resolution pertaining to Superpave called for:  The allocation of National Cooperative Highway Research Program funds to support high- priority aspects of a program of Superpave development and deployment;  The establishment at TRB of an “oversight” committee to advise AASHTO and FHWA on the content, conduct and financial needs of this program; and  Development of a long-range plan for the Superpave program. In 1999 the state DOTs were expected to award approximately 3,000 asphalt paving projects that would employ the new Superpave tests and specifications. This represented about 46% of the hot-mix tonnage placed by the states. By 2000, nearly all states were expected to adopt the binder specifications and most would be using the mix design procedures. While much had been accomplished, there are still some gaps in knowledge and key elements of Superpave that needed refinement. For example, more work was required to:  Relate asphalt binder specifications to field performance, especially for modified binders;

142  Sort through complex Superpave performance-related tests and prediction methods to identify a “simple” procedure that could be used to confirm design values, and guide quality control and quality assurance;  Validate the Superpave procedures and specifications by looking back at some Superpave mixes that had up to five years of field service;  Assure that specification parameters and tolerances are set so that cost-effectiveness and product quality are maintained at an appropriate balance. In this far-reaching resolution (23), the AASHTO Board of Directors stated that $5.6 M in support of Superpave and other hot-mix asphalt research would be required as follows: FHWA – Superpave Projects Continuation $2.200 M NCHRP Project 9-19 $1.700 M NCHRP Project 9-20 $1.500 M SHRP Lead State Program (includes Superpave among others) $0.050 M TRB Program Support $0.150 M NCHRP Projects 9-19 and 9-20 enabled completion of research begun by FHWA to develop simple performance tests for Superpave-designed mixes (9-19) and an HMA performance-related specification through the WesTrack experiment (9-20). The dollar amount and the speed of processing new contractual arrangements kept the Superpave program going with no stoppages or delays. 5.5.2 TRB Superpave Committee Heretofore, Superpave implementation had been steered through the FHWA Technical Working Group and the Expert Task Groups. On December 8, 1998, as stipulated in AR5-98, TRB, FHWAA and AASHTO formed the Superpave Committee (E1006) at TRB. The Committee membership is shown in Table 17. This Committee was different in that it had no control of funds and only had the power of recommendations. It did, however, hold the purse strings on the Expert Task Groups. The AASHTO Subcommittee on Materials had become very dependent on the recommendations from the ETG to support the development of standards and continuation of the ETGs was considered essential to future progress. The first meeting of the TRB Superpave Committee was held in March 1999. At that meeting, the Committee fully endorsed the need for national coordination and oversight at this critical stage of Superpave implementation. The Committee reviewed the program of Superpave research then under consideration by AASHTO for inclusion in the FY 2000 work program of NCHRP and recommended 11 projects with a total cost of $3,275,000. The Committee also initiated discussion of a long-range plan for Superpave development and deployment (discussed in Section 5.5.5) and the reconstitution of the Superpave Mix and Binder Expert Task Groups, formerly supported by FHWA.

143 Table 17 Members of the TRB Superpave Committee Name Organization Joseph A. Mickes, Chair Missouri DOT David Anderson Pennsylvania State University Martin F. Barker City of Albuquerque, NM Wade Betenson Utah DOT Frank Danchetz Georgia DOT Fred M. Fehsenfeld, Sr. The Heritage Group John Haddock Purdue University Eric E. Harm Illinois DOT Dallas N. Little Texas A&M University Donald W. Lucas Indiana DOT Paul Mack New York State DOT Joe P. Mahoney University of Washington Charles R. Marek Vulcan Materials Company John B. Metcalf Louisiana State University Gale C. Page Florida DOT Charles F. Potts APAC, Inc. Douglas R. Rose Maryland DOT Byron Ruth University of Florida Dean C. Weitzel Nevada DOT Y. T. Yarnell Wilbur Smith Associates Mike Acott (Liaison) National Asphalt Pavement Association Ken Kobetsky (Liaison) AASHTO Bernard M. McCarthy (Liaison) The Asphalt Institute Vincent F. Schimmoller (Liaison) FHWA Sarah Wells (Liaison) Transportation Association of Canada Greg Smith (Liaison) American Road and Transportation Builders Association Ted Ferragut (Consultant) TDC Partners Neil F. Hawks (Staff Rep.) TRB Since meetings of the Superpave Committee were only planned for every six months, TRB asked staff from FHWA and AASHTO to meet much more frequently to support the work of the Superpave Committee. Termed the TRB Superpave Support Group, the members from all three organizations had experience in Superpave technology and program management. They proved invaluable as a continuing resource to the Committee. The Support Group immediately pulled together a comprehensive list of projects for consideration by the Committee, prior to evaluation by AASHTO’s Standing Committee on Research and ultimately by NCHRP. The Committee, however, was not a rubber stamp to the Support Group recommendations. The Committee recommended deferral of four projects that they believed did not need to be pursued immediately. The Committee also deferred the Support Group’s request for additional research on moisture sensitivity of Superpave mixes, pending results from other NCHRP work.

144 AASHTO’s Standing Committee on Research (SCOR) reviewed in detail the Committee’s slate of projects and recommended funding. They clearly saw the need for Superpave continuation and approved 13 projects outright and one project for contingent funds. The only project not approved was a $1.0 M request to support a second FHWA Superpave mobile laboratory. SCOR recognized the contribution the mobile laboratories had made to Superpave implementation and suggested that the TRB Superpave Committee explore other possible funding techniques, including direct industry and state support. In April of 1999, the AASHTO Board of Directors adopted the SCOR recommendations. After reviewing the SCOR and Board of Directors’ decisions for FY 1999 and FY 2000, the Committee immediately worked on a preliminary slate of eight new and five continuation projects for the NCHRP FY 2001 program, including the development of project statements. To address the unresolved issue of moisture damage sensitivity of asphalt mixtures, the Committee sponsored a national focus group to consider the issue and suggest a course of action. In July 1999, nearly 30 national experts explored the issue of moisture damage in asphalt pavements. They collectively reviewed past and current work, and then broke into two smaller focus groups. Both groups independently agreed that moisture damage was a national issue and recommended the continuation of research. A problem statement was drafted for consideration by the Committee in upcoming meetings. Of critical significance at the second meeting of the TRB Superpave Committee in June 1999, the Committee approved the formation of two Expert Task Groups under TRB auspices. The Mix ETG would focus on mix and aggregate issues, the Binder ETG would focus on binder issues. The Committee also reviewed and discussed additional concepts for the long-range Superpave plan, looking at potential projects, budgets, and a timeline. The committee was operational between 1998 a nd 2004, hol ding 11 meetings. Each meeting was followed by a letter report from the chair to the Executive Director of AASHTO and Administrator of the FHWA. 5.5.3 The ETGs Under TEA-21 The newly constituted Mix ETG met in September 1999 and reviewed a full slate of outstanding technical issues, including key aggregate issues. The ETG established task forces that would monitor the conduct of FHWA research being supported with NCHRP funds. The ETG also provided recommendations on the draft long-range plan prepared by the Superpave Support Group and the FY2001 project statements. Finally, the ETG established a communication procedure among the members of the Superpave Committee, the Binder ETG, the Superpave Lead State Team and the AASHTO SOM. The ETGs continued to meet and advance the technology through the TEA-21 years with the support of TRB. 5.5.4 Survival So, with the support of AASHTO and the states and the cooperation of FHWA and TRB, the work on Superpave implementation was able to proceed. Significant NCHRP funding supported additional research to refine the system and pick up what would otherwise have been lost because of FHWA’s reduced funding. In a sense, the states were again taking charge of their research products. The TRB Superpave Committee was addressing the key elements of AR 5-98 (23):

145  The Superpave development and deployment program was moving forward with the support and participation of AASHTO, FHWA, the individual state DOTs, and the hot-mix paving industry;  Mechanisms to monitor and coordinate Superpave and related hot-mix asphalt research had been established; and  An effective long-range financial and technical plan for completion of Superpave implementation and deployment was under development. In many respects, 1999 was a landmark year. Superpave implementation had survived – not entirely intact, but beyond the ‘doomsday’ vision that many had when TEA-21 was passed. It had funds, it had projects, it had steering and technical committees. For 2000 and beyond, the TRB Superpave Committee believed it was important to focus on four key issues and continue the push to:  Assure that the remaining Superpave technical issues were properly identified and addressed;  Assure that the financial estimates required to complete Superpave were justified;  Integrate this information into a long-range plan that would become the blueprint for completion of Superpave; and  Assure that sufficient emphasis was placed on a communications, publications, training, and outreach program that would effectively deliver Superpave to the ultimate users. The Committee foresaw no immediate remedy to the severe reduction of discretionary resources within FHWA. In the absence of a remedy, the Committee continued to provide recommendations to AASHTO and FHWA on the content and conduct of a financially constrained program. 5.5.5 Superpave 2005 So in 1999, with leadership from AASHTO, FHWA, and NCHRP, the Transportation Research Board had established the TRB Superpave Committee to review work plans of AASHTO and FHWA research, advise on objectives and tasks, identify missing components, and suggest coordination of activities. Expert task groups (ETGs) for binders, mix/aggregate, and communications/training were formed to assist the committee. “We had everything but a final goal. We needed to focus on when we would be done,” noted Superpave Committee chairman Joe Mickes. “We had been at this now since the early 1980s. We were not going to keep going forever. That led us to develop a longer-range plan – Superpave 2005.” The TRB Superpave Committee also decided that it would sunset by 2005 to enforce its timeline (31). Four major goals were identified that would round out the implementation phase of the program. They would define completion of the program. Goal 1. Superpave will recommend binder type (including modified binders) and mixture proportions based on environmental and loading conditions and pavement design Goal 2. Superpave will predict the ability of a mix to withstand rutting, fatigue, thermal cracking and moisture damage.

146 Goal 3. Superpave will integrate the binder and mix requirements into a performance- based construction quality control specification system Goal 4. Superpave will be clearly understood by public and private-sector engineers, technicians, and contractors through initial and continuing training and outreach programs. Goal 1 focused on ensuring that the binder specifications would be blind to modification. The key to Superpave performance-based binder specification is that the physical properties required for the binders are the same for all grades but the temperature at which those properties must be attained should fit the specific climatic conditions at the paving location. This was always a goal of the research phase of the program. The Superpave binder specification at the time accommodated virtually all unmodified binders, but not all modified binders. In 2002, the Binder ETG continued to review NCHRP and FHWA-managed research on laboratory test methods to better characterize modified binders. To investigate the relationship of these laboratory measured characteristics to performance, 17 states and 20 industry groups agreed to join in an FHWA-administered pooled-fund study using the FHWA’s Accelerated Loading Facility (ALF) to test twelve lanes of Superpave mixtures made with various modified binders. While some of the research is now complete and standards have been developed for revised tests and specification tables, the revised test methods are still not widely used. Recent research at FHWA to develop the Multi-Stress Creep and Recovery (MSCR) test with application for modified and unmodified binders seems to be generating more attention than previous test protocols and may eventually be widely implemented. Goal 2 focused on performance predictions. A major objective of the Superpave system was the prediction of the field performance of specific HMA mixtures based upon laboratory tests. Researchers developing the Mechanistic-Empirical Pavement Design Guide (MEPDG), under NCHRP 1–37A, incorporated a refined Superpave indirect tensile test and a recalibrated Superpave model for thermal cracking into their work. This helped link pavement design and performance prediction to actual laboratory derived mix design values for low-temperature cracking properties. Many states are now in the process of or have already implemented the new pavement design procedures. Also in 2002, three candidate simple performance tests for the Superpave volumetric mix design methods were identified under NCHRP Project 9-19. Test equipment manufactured by the private sector was evaluated under NCHRP Project 9-29. The Asphalt Mix Performance Tester (AMPT) is now being purchased by many states through a pooled fund and looks like it will be widely implemented, in support of both mix design and MEPDG implementation by the states. It remains to be seen how many industry labs purchase the equipment; that will no doubt be a longer process. With committee support, research on the fundamental mechanisms of moisture sensitivity (stripping) is continuing through FHWA-managed research at the Western Research Institute in Laramie, Wyoming. NCHRP continues to tackle this difficult issue through a variety of projects looking at the moisture susceptibility of both HMA and WMA. Work is ongoing on Goal 3, which focused on the relating binder selection and mix design to construction and performance. Performance -related specifications link key HMA parameters under the control of the contractor to laboratory determined test values, which can be used to predict the life of the as-built pavement to the as-designed pavement. A recently

147 completed NCHRP project (9-22, Beta Testing and Validation of HMA Performance-Related Specifications) developed software derived from the MEPDG to allow these comparisons and develop pay factors based on the anticipated pavement life compared to the design life. The final goal, the Communications goal, focused on getting the word out through communications. Everyone had agreed that communications during the first phase of implementation had been key to informing the broad based community as well as the technical community. The Communications and Training ETG was formed in 2001 to promote understanding of the Superpave system. The ETG was fully operational in 2002. It supported the development of a history of Superpave, an integrated mix design manual, a Superpave electronic newsletter, and support of national conferences. The ETG worked with the Transportation Curriculum Coordinating Committee (TCCC, a pooled-fund effort of DOTs supporting efficiencies in training) to assist in the development of Superpave-related training programs. The TCCC released two revised Superpave training modules in early 2011. In support of this goal, NCHRP funds were approved for NCHRP Project 9-33 to develop the final Superpave communication and training product – a compendium of revised mix analysis methods, software, and manual.. The manual was published in 2011 as NCHRP Report 673, “A Manual for Design of Hot-Mix Asphalt with Commentary.” While the Committee recognized that Superpave was perceived as a product for use by state DOTs, in reality the Superpave system was equally applicable to city, county and local road and street networks. In 2002, the committee asked the Superpave Support Team to develop a Superpave workshop for attendees at the 8th International Conference on Low-Volume Roads in June 2003, in Reno, NV. Many states have now embraced Superpave fully and have removed Marshall, Hveem or other mixes from their specifications; local agencies have increasingly used Superpave mix designs as well. In many places, industry has helped to encourage local agencies to adopt Superpave. The Superpave Centers have also assisted in this effort through training and technology transfer. The Center at Penn State hosted a workshop in the northeast in 2001 that led to a white paper on use of Superpave for low-volume roads (32). Slowly but surely, use of the technology is becoming pervasive. Funding uncertainties brought about by the failure of the national legislature to agree on a budget led to a long gap between meetings of the TRB Superpave Committee in 2003-2004. The TRB Superpave Committee held its eleventh and final meeting on December 6, 2004. The committee had earlier agreed to sunset in 2005. Future enhancements would fall under the banner of improved asphalt technology rather than fulfillment of the Superpave system. 5.6 TECHNOLOGY ADVANCEMENTS AND CHALLENGES DURING IMPLEMENTATION It has been noted earlier that many of the SHRP products related to Superpave were not fully ready for wide-scale implementation. This section will summarize some of the technological challenges and advancements that were made during the implementation phase. It will also start to give a picture of the state of the practice today.

148 5.6.1 Binder Testing and Specifications There had been approximately 15 versions of the PG binder specifications prepared and modified during the research phase. Eventually, the framework and guiding concepts were set, and they are still in use today, for the most part, though there have been refinements in some of the testing procedures, application of the specifications, proposed new test methods, etc. The pooled-fund equipment buy was instrumental in getting the technology into the hands of the state DOTs but not industry. The real push to get industry outfitted to perform the testing came when it became obvious that the states were going to specify PG grades. As the number of pieces of equipment in use increased, issues began to crop up. For example, early round robin testing showed that the variability in testing results between labs was quite high – the acceptable range of test results between multiple labs could be over 50% in some cases. There was concern over this variability, but increased training and experience, plus greater attention to calibration, brought the variability down significantly. There were also some differences between different brands of equipment that came to light. For instance, there were differences in how time zero was defined and the shape of the beam supports between different brands of BBR. Once these differences were discovered, they could be resolved, so they were really minor glitches in implementation. More significant problems were discovered very early on with the direct tension test device. The initial device used an air-cooled test chamber, vertical specimen mounting and a laser to detect breakage of the specimen. Obtaining reliable and repeatable test results with this configuration proved to be extremely difficult; so difficult, in fact, that the device was not included in the pooled-fund equipment buy. The test was pulled from the specifications and the equipment was completely redesigned. A fluid bath, horizontal specimen mounting, and detecting breakage by the drop in resistance to pulling made the test much easier to perform and more repeatable. The test was added back into the specifications but is optional and rarely used. One concept behind the PG specifications that was somewhat less successful than planned was the concept that the specifications would be blind to binder modification; that is, that modified and unmodified binders could be tested the same way and held to the same standards. This was an attractive concept to many DOTs, which had been struggling with how to specify modified binders generically in a low-bid culture. It was soon recognized, however, that the originally proposed test protocols did not adequately characterize the enhanced performance generally provided by modified binders. Several research projects were conducted to address this issue, most notably NCHRP 9-10, Characterization of Modified Asphalt Binders in Superpave Mix Design. The research team, led by Hussain Bahia of the University of Wisconsin, Doug Hanson of NCAT and Mike Anderson of the Asphalt Institute, offered several test protocols that would better characterize modified binders. The research team recommended replacing the DSR rutting parameter G*/sin δ by the viscous component of creep stiffness, Gv; replacing the DSR fatigue parameter G*sin δ by a fatigue life parameter, Np, measured in a repeated cyclic loading test in the DSR; and evaluating the glass transition temperature for low-temperature cracking. The research also developed a Particulate Additive Test (PAT) to determine if the modified binder contains more than 2% particulate material, in which case mixture testing is required to evaluate the modifier. A storage stability test was also developed. Despite the fact that most of the proposed tests used existing equipment, with modifications, the protocols were not adopted nor are they widely used today.

149 FHWA has continued working with a Multi-Stress Creep and Recovery (MSCR) test to better account for the effects of modified binders. This test protocol also uses the DSR, with modifications to the software, and does seem to be gaining greater acceptance. There have been other efforts to develop improved binder testing protocols, but to date they have not been widely accepted. For example, research efforts have investigated the binder aging protocols in an attempt to address some perceived shortcomings with the current RTFO and PAV protocols. The Binder ETG remains on the forefront of the continuing efforts to refine the system. In addition to equipment and testing issues, there have been issues with interpretation of the meaning of the test results and selection of the proper binder grade. For example, early versions of the LTPPBind software frequently recommended -34 grade binders for wide swathes of the northern United States. Producing such soft binder grades was challenging for refiners and often the binders were much softer than had been used in those areas previously. Research at instrumented pavement sections in Canada and elsewhere helped to demonstrate that the original recommendations were overly conservative. Eventually, LTPPBind was modified with new low- temperature algorithms that yielded more reasonable estimates of the required low-temperature grade. Earlier FHWA guidance had advised to carefully consider whether use of such a low temperature was appropriate. As another example of the interpretation of the data, some colorful maps were prepared to show the binder grades recommended for different areas of the country. In short order, it was determined that such maps were not detailed enough to be used to select project-specific binders. They could be used as rough guides for marketing purposes only. In some cases, state agencies made “liberal” interpretation of the binder selection criteria to reduce the number of PG grades in the state. 5.6.2 Mixture Testing and Specifications One of the earliest sticking points on the mixture side of Superpave implementation was the restricted zone. This area of the gradation specification had been included as a warning that gradations passing through that zone could exhibit tenderness problems during construction. The recommendation to avoid gradations passing through that region was based on previous experience with Marshall mixes. There were states, however, that had good experience with some mixes that passed through the so-called restricted zone. Resistance to implementing this zone was high, especially in states like Georgia that had those mixes they felt performed well. Some states never did institute the restricted zone. Eventually the warning was removed from the specifications entirely. Another contentious issue was the range of fine aggregate angularity (FAA) values recommended for different traffic levels. Because natural aggregates were frequently not able to meet the FAA requirements, states were facing increased use of manufactured sands. In some states, aggregate suppliers and industry associations warned that they might not be able to produce enough material with high enough angularity. Vast shortages were predicted for some areas of the country. There was also concern in the industry that the often higher angularity requirements on both the fine and coarse fractions could lead to increase equipment and processing costs and increased waste of non-spec material (particularly excess fines). Despite the cries of doom, great shortages did not materialize. Existing material suppliers were able to adjust, for the most part, and produce the required materials. There were – and in some cases still

150 are – issues with excess fine aggregates being generated, so industry and agencies are working on identifying beneficial uses for these materials. Finer mixes and small nominal maximum aggregate sized mixes (4.75 mm) are being used more widely, which is lessening the problem to some extent. Early Superpave mixes for high volume roadways were typically designed as coarse mixes; the need to avoid the restricted zone, which tended to favor fine mixes, contributed to this trend. Coarse mixes were uncommon in many states prior to Superpave, so their use represented a great departure from standard practice. Results from WesTrack and other research, however, demonstrated that fine-graded Superpave mixes could perform well – in some cases better than coarse mixes. (See Section 5.6.4.3.) Consequently, many states have started using more fine- graded mixes, even for high traffic volumes. Large quantities of reclaimed asphalt pavement (RAP) were accumulated (and are still accumulating) in some parts of the country, particularly in urban areas. The original Superpave mixture specifications did not disallow the use of RAP but there was no guidance on how to incorporate RAP. Besides, contractors and agencies were trying to come to grips with a new set of material and mix design requirements; they were reluctant at first to introduce another variable. The FHWA Mixture ETG issued some interim guidance on the use of RAP in 1997, based on previous experience with Marshall mixes. The use of RAP in Superpave slowly began to increase. In early 2001, the findings of NCHRP 9-12, Incorporation of Reclaimed Asphalt Pavement in the Superpave System, were released and revised AASHTO specifications were adopted. Within a few years, the use of RAP had generally increased back up to pre-Superpave levels in most parts of the country. The use of higher percentages (25-50%) of RAP is still an issue in 2011 and another FHWA ETG has been established to investigate and promote the use of higher RAP contents. The Superpave Gyratory Compactor is standard laboratory equipment now. There have, however, been changes in that equipment as well. Differences were noted between the densities produced by different brands or models of gyratory compactors. As these were investigated, it was discovered that the actual angle of gyration applied to the mix inside the gyratory mold could vary, especially as mix stiffness varied and affected the machine compliance. This led, eventually, to specifying the angle of gyration based on measuring the angle inside the mold rather than on the outside. Devices that could simulate the presence of a mix and allow measuring the internal angle have been developed and are now required in the AASHTO specifications for calibrating the internal angle. 5.6.3 Performance Testing As discussed previously, the ultimate vision for Superpave was to base all mix designs on volumetric principles, then do testing for higher traffic volume roadway designs to ensure that the designed mixtures would perform as needed. The testing was to facilitate the prediction of the distresses that would be likely to occur for those mixes under the traffic and environmental conditions at the project location. A three-tier design system was described with increasing levels of testing for higher traffic volumes. This vision has not yet been fully realized. The proposed testing was to be conducted in the Superpave Shear Tester (SST) for high and intermediate temperature properties (rutting and fatigue) and Indirect Tensile Tester (IDT) for low-temperature properties (thermal cracking). (The FHWA, Superpave Centers and a handful of labs around the country were outfitted with the SST and IDT.) The data obtained from

151 these tests was then input into software that would predict the rutting and cracking likely to develop. While the low-temperature prediction models were generally acknowledged to correlate fairly well to thermal cracking, the rutting models in particular appeared to have problems. In part this may be credited to the fact that the projects developing the models and the project developing the tests were not as well integrated as they should have been. In addition, the equipment was expensive and fairly complicated to run. The end result was that the tests and the models were never widely used. Both the SST and IDT have been used successfully for research purposes, such as in NCHRP 9-10 and 9-12. In addition, the tests and the software have been used for the design of a few high profile warranty projects. It is safe to say, however, that the higher level design methods have not been widely implemented. In addition, other research efforts since SHRP have moved in another direction. The MEPDG for flexible pavements incorporates the dynamic modulus of the mixture. Other NCHRP projects have led to commercially available equipment – the Asphalt Mixture Performance Tester (AMPT) – to conduct the dynamic modulus and other test methods. States are now in the process of purchasing the AMPT and implementing the MEPDG. The Models ETG is still in existence and is overseeing the implementation and eventual refinement of models to predict pavement distress and performance. 5.6.4 Construction As the use of Superpave mixtures increased, reports began to surface of construction issues in the field. In most cases, these issues were related to the changes in the gradations, stiffness and production temperatures of the mixtures. Many of these could be resolved by relatively minor adjustments in procedures. In other cases, the problems pointed to issues that required greater adjustments. For example, in areas where Superpave aggregates were coarser or harder than the previously used materials, contractors reported some increased wear in some equipment – such as flights in drums, paddles in batch plants, paver augers and screed plates. Other production issues included changes in the drying time and efficiency, greater aggregate breakdown and VMA collapse with coarser mixtures, higher production temperatures for modified mixes in particular, the need for more cold feed bins to accommodate the large percentages of coarse aggregate, etc. At the paving site, increased segregation was observed with some coarser mixes. Handwork was often reported to be more difficult, especially with modified binders. Modified binders also tended to stick more to truck beds. The biggest construction issues, however, were definitely related to compaction. Coarser, stiffer, modified mixes were harder to compact in the field. In most cases, compaction could be improved by changing some production parameters and construction techniques. Keeping the mixes hot was found to improve compactability markedly, so higher production temperatures, the use of tarps and insulated truck beds, and keeping rollers up close to the paver to achieve compaction while the mix was hot were all found to be effective techniques to improve density. Changes in rolling patterns and the types of compactors used were also successful in many cases. But not in all. 5.6.4.1 Changes in Compaction

152 There were many reports from the field of increased mix tenderness. This tenderness interfered with compaction of the mixes. The tenderness seemed to differ from traditional mix tenderness that seemed to be related to the aggregate gradation (and was the raison d’être for the restricted zone). The particular tenderness reported with Superpave mixes seemed to be related more to the mix temperature; typically there was a range of temperatures, which varied between projects and mixes, where compaction could be more difficult and sometimes additional roller passes actually decreased the density. Research eventually showed a relation to the total fluids content in the mixes. Contractors often learned how to work around the tender zone by doing most of the rolling immediately behind the paver, then staying off the mat until the mix cooled below the tender zone. Once the mat cooled sufficiently, finish rolling would be applied. Sometimes changing the types of compactors also helped; often pneumatic rollers could be used through the tender zone. The tender zone was not reported on all projects. Estimates at the time suggested that fewer than 25% of Superpave projects exhibited the tender zone. Today the tender zone is almost never discussed. Contractors have learned to avoid it or deal with it as needed. 5.6.4.2 Florida Permeability Issues The Florida DOT set a pretty aggressive schedule for implementation of Superpave mixtures. They had been experiencing problems with premature rutting and other distresses, so welcomed the potential to improve performance with Superpave. Ten Superpave projects were constructed in 1996 in the state. Achieving the required density was challenging in many cases. Shortly after construction, several of the projects began to exhibit permeability problems (33). Specifically, water could be observed seeping into or out of the pavement. This raised concerns that there could eventually be stripping problems on these pavements. FDOT immediately began investigating the case of the permeability, how to measure it and how to prevent its occurrence on future projects. This eventually led to recommendations to increase the lift thickness to allow room for the coarser aggregate particles to reorient under the rollers, thus improving the density and reducing permeability. In keeping with their role as a Lead State, FDOT was willing to “go public” with the problems and their solution, so the greater community could learn from their experience. The recommendation to increase the lift thickness to four times the nominal maximum aggregate size for coarse mixes was adopted by many other states as well as Florida. 5.6.4.3 WesTrack In 1995, under a contract awarded by the FHWA, 26 test sections were placed on a 3 kilometer test track in the Nevada desert. WesTrack, as it was known, was primarily established to develop performance-related specifications for hot-mix asphalt. The test sections were designed to evaluate the effects of varying binder contents, gradations and in-place air voids on mixture performance. Since these mixes were designed according to the Superpave mix design requirements, a secondary objective of the contract was to provide early verification of the performance of Superpave mixes. Automated (i.e., driverless) triple trailer trucks were used to apply accelerated traffic loading to the test sections. In two years, 4.5 million ESALs were applied to the pavement, which is a very high rate of loading. Early failure of some of the test sections, including the coarse-graded mixes that were expected to perform well, raised concerns among the highway community about the mix design system. After the application of some 2.7 million ESALs (Spring 1997), nearly every section had rutted, some severely. Fatigue cracking had also appeared in many of the test sections, although

153 conventional wisdom would say fatigue and rutting typically do not happen in the same mixtures because of their conflicting mechanisms. The mix design procedure favored coarse mixes, but WesTrack suggested that these mixes, in particular, would be prone to performance problems. Because of the severe rutting and fatigue cracking, ten sections were replaced in May-June 1997; eight using the original coarse-graded design but with a more angular coarse aggregate and two using standard Nevada DOT mixes with polymer modified binder. Surprisingly, most of the replacement sections failed even faster than the original sections had failed. Significant rutting began to occur in as few as five days. This increased the concerns that there might be something wrong with the Superpave mix design system. The asphalt community was abuzz with rumors and speculation. Prompt action needed to be taken to dispel the rumors before the whole Superpave system was derailed. To examine the results at WesTrack and determine the likely cause(s) of the problems in the coarse-graded mixes, FHWA assembled a forensics team consisting of academicians, state highway engineers, consultants and industry personnel. Two FHWA representatives also participated in the deliberations. (The forensics team membership is shown in Table 18.) Table 18 WesTrack Forensic Team Members Name Organization Ray Brown NCAT Erv Dukatz Mathy Construction Co. Gerald Huber Heritage Research Group Larry Michael Maryland State Highway Administration Jim Scherocman Consulting Engineer Ron Sines New York State DOT John D’Angelo FHWA (Liaison) Chris Williams FHWA (Liaison) The mixes had been designed for 10 million design ESALs. Because of the accelerated rate of loading, however, the loadings were very concentrated. Had the traffic continued at that rate for a full 20 year design life, the total loading would have exceeded 75 million ESALs (34). The forensics team developed a plan of laboratory testing to evaluate the properties of the in-place mixtures. Testing included determining the gradations and volumetrics of field samples, conducting SST and loaded wheel tests, evaluating extracted binder and more. These results were compared to results of tests during production. After extensive analysis and debate, the forensics team issued a final report (35). The majority opinion expressed in the report was that the premature rutting observed was primarily due to a relatively high binder content. This high binder content was caused by high VMA in the aggregate structure which in turn required a high design binder content to fill the voids. This was exacerbated by over-asphalting during production. Mixes with higher dust to binder ratios performed better than those with lower dust to binder ratios, likely because of the greater effect the higher dust content had on the mastic stiffness. The final report conceded that mixture volumetrics alone might not be enough to guarantee the performance of asphalt mixes under high traffic volumes. A subset of the forensic team members (Gerry Huber, Jim Scherocman and Erv Dukatz) offered another explanation (35). They felt the thickness of the pavement structure played a role in the observed distresses. The tangential sections were designed with thinner cross sections than

154 in the curves and the mixes in the curves did not rut as much as in the tangents. Their theory was that coarse-graded mixes experience more strain in the mastic than fine-graded mixes because there are fewer points of contact between the aggregates. In thin pavement sections, these mixes will experience high strain that can explain both the rutting and fatigue cracking observed. Recommendations were made to improve Superpave mix design based on the lessons learned at WesTrack. Many of these were eventually codified in the AASHTO mix design standards. Key among the recommendations:  The dust to binder ratio was increased for coarse-graded mixes (from 0.6-1.2 to 0.8-1.6).  A maximum VMA should be established to reduce the likelihood of high design binder contents – for coarse-graded mixes the maximum VMA was recommended to be no more than 2% above the minimum value.  Volumetric properties, including VMA, should be measured on plant-produced mixes.  The Ndesign should be based on a 20 year design life, regardless of how long the pavement is expected to perform. In other words, the rate of traffic loading, not just the total traffic, has a great effect on pavement performance. By basing all designs on a 20 year design life, the rate of loading can be taken into account.  A performance test should be performed on mixes for high volume roadways after the volumetric mix design is completed. Although the loaded wheel testers and SST “showed some merit,” the search for a reliable rutting performance test continues. With the issuance of the final report, plus mix design guidelines based on the WesTrack experience, some of the furor and concern about WesTrack abated. Case studies of good performing Superpave mixes also helped to defray the concerns and show that the results at WesTrack were not representative of what was happening under normal traffic conditions. 5.6.4.4 Asphalt Institute Field Survey In response to widespread rumors about Superpave construction projects in about 1996, the Asphalt Institute reviewed 86 of the estimated 93 Superpave projects constructed in 1996. The projects ranged in size from small test sections to large-scale construction projects. The review was conducted by a variety of means from phone calls to in-person interviews. The review attempted to identify how many field projects exhibited some kind of construction problem, what those problems were, what factors might have contributed to the problem and how they were addressed. The survey concluded that roughly one-third of the projects constructed in 1996 exhibited some construction issue. This was not felt to be unreasonable when implementing a new system. The issues were mainly in terms of: • Meeting density requirements (compaction); • Meeting VMA requirements; • Segregation; • Shoving under the intermediate roller; • Mixes with modified binders sticking to pneumatic tires on rollers (“pick up”); • Mixes sticking to truck beds. The report also noted that many of these issues were resolved in the field during construction by changing the practices (changing roller patterns, using different rollers in different positions, watching mix and mat temperatures, etc.). Other remedies were also offered, such as increasing

155 lift thicknesses to allow for better compaction, changing the design gradation or increasing the crushed content to increase VMA, changing release agents and more. The real significance of this document (36) was that it showed two-thirds of the Superpave projects had no issues during construction, even though these mixes were still relatively unfamiliar to most states and contractors. The responses from the states showed several instances where contractors expressed a preference for Superpave over Marshall mixes. This helped to dispel some of the doom and gloom that had been accumulating in light of some widely publicized (or rumored) problems. The report also offered practical suggestions for dealing with similar problems, if they occurred, giving practitioners some guidance they could rely on. 5.7 WHERE ARE WE TODAY? The preceding discussion has highlighted some of the changes that have occurred in Superpave as implementation has progressed and has given some hints of where we stand today, nearly 18 years after Superpave implementation began in earnest. To summarize the current situation, the following is offered. 5.7.1 Binders The PG binder specifications and tests are almost universally used around the country. They have been incorporated in state specifications and are now widely used by local agencies and in private work as well. In large measure, this widespread implementation has been driven by industry and their reasonable reluctance to maintain two systems. The goal of adopting a uniform binder specification across the country was not realized in total. A large number of states – more than half – have adopted what are known as “PG+” specifications, particularly to accommodate modified binders, where they start with the “pure” PG specifications and add additional tests or requirements. Force ductility is a commonly used plus, but there are many differing ways to run that test. Phase angle requirements are also frequently specified. Many states require particular forms of binder modification (such as SBR) or disallow some types (such as polyphosphoric acid). Several states in the southeast have adopted a PG67-22 binder grade to match more closely to the AC-30 binders they used pre- Superpave. The Binder ETG and other groups continue to work on refinement of the binder tests and specifications but the original framework and concept is still largely in force. Many hope that implementation of the new MSCR test will remove the need for the PG+ tests used in many states and promote a more uniform system. 5.7.2 Mixtures and Construction The Superpave mix design system is now widely used but not in every state. California has recently moved to implement Superpave but Tennessee and Nevada are among the few states that do not. In many of the states that did adopt Superpave mixes, the use has now become routine and often the mixes are no longer called Superpave – they are simply hot-mix asphalt, or sometimes are known as gyratory mixes.

156 As use of Superpave has become routine in individual states, the use by local agencies and in private work has also increased. In some cases, owners may not realize that they are getting Superpave mixes, but that is what contractors provide. The use of RAP has increased and continues to increase. Other recycled materials, such as shingles, are also being used. Issues related to aggregate do not appear to be as numerous or troublesome as they were initially anticipated, by some, to be. Construction issues related to Superpave mixtures in particular have largely been resolved (though of course there are still issues, as, of course, there were before implementation of the Superpave system). The Mixture and Aggregate ETG is also continuing to look to improve asphalt pavement performance. The use of Warm Mix Asphalt is coming on very strong and is the focus of a great deal of research and field implementation. 5.7.3 Models Work continues on evaluating models to predict pavement performance based on measuring fundamental engineering properties. The focus has shifted away from the models pursued during SHRP, however, to those recommended in the MEPDG. The Models ETG continues their oversight role in this regard. The MEPDG models have been incorporated into mix design and performance-related HMA specifications (through, for example, NCHRP Projects 9-19, 9-22, 9-30A, and 9-33A). The final report for NCHRP Project 9-22 (NCHRP Report 704, “A Performance-Related Specification for Hot-Mix Asphalt”) and its associated software allow states to compare the as- built to the as-designed materials to assess the impacts of construction QA on the performance life of the pavement. Additionally, work continues to define develop models for top down cracking and reflective cracking for future integration in DARWin ME, the AASHTOWare program developed from the MEPDG. 5.7.4 Construction Superpave has become business as usual for contractors across the country. While construction issues continue – and will likely continue as long as we continue to construct asphalt concrete pavements– those issues are typically not attributed to Superpave mixes. They are simply a fact of life. The improvements that are widely recognized as resulting from the implementation of Superpave, such as greatly reduced rutting and improved resistance to thermal cracking, have allowed us to see other problems that probably existed before but were overshadowed by more pressing, more visible problems. Work continues to resolve issues like longitudinal joint construction, segregation, etc.