Significant Findings from Full-Scale Accelerated Pavement Testing (2012)

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98 IntroductIon This chapter provides detailed information on the impacts and economic analysis of f-sAPT findings from 2000 to 2011. The impacts indicated by respondents to the questionnaire are dis- cussed, followed by information on the economic analyses. Finally, the impacts of f-sAPT on general pavement engineer- ing practice in terms of learning activities are discussed. Impacts Respondents viewed improved structural and material design methods, evaluation of novel materials, improved perfor- mance modeling, and the development of performance-related specifications as the major benefits of f-sAPT (Figure 49). The most significant findings from f-sAPT in the last decade for respondents’ own f-sAPT programs contain a vast collec- tion of specific topics focusing on all aspects of pavement engineering. Issues around materials characterization, pave- ment modeling, pavement behavior and performance, pave- ment design method development and calibration, benefits of specific materials, and technologies and economic impacts of f-sAPT programs provide a small sample of these highlights. Aspects that do stand out is the number of respondents indi- cating that technologies that are viewed as environmentally friendly, such as WMA and the use of RAP, are significant in their programs. Full details of the responses are contained in Appendix C. The most significant international findings of f-sAPT in the last decade can be summarized on a strategic level as the calibration of pavement design methods (specifically MEPDG and CalME), development of databases of infor- mation on pavement performance that are shared between different pavement research programs, cost savings through implementing f-sAPT, and the development of improved instrumentation and analysis methods. In terms of more practical examples, issues such as an improved understand- ing of failure mechanisms of top-down cracking, critical strain limits in HMA, the effect of adequate layer compaction, variability of materials and layer properties, improved under- standing of the links between various materials’ laboratory and field behavior, and the effect of various real environmental conditions and traffic on pavement behavior and performance are seen as major international findings. Specific aspects again focused on respondents’ own cir- cumstances and included issues such as a better understand- ing of top-down cracking of HMA, improved understanding of shear stresses, durability of HMA layers, bituminous binder replacements, evaluation of problematic issues such as ortho- tropic bridge decks, quantitative benefits of geogrids, and HMA aging models. In response to the question on major specific tests con- ducted by facilities and the benefits of their activities, a host of different answers were obtained. As would be expected, most of these answers are not generic as each of the programs has very specific reasons why they conduct their f-sAPT and they need to ensure that the objectives and research ques- tions of their sponsors are addressed sufficiently. It is clear however from the feedback (details in Appendix C) that the various f-sAPT facilities are conducting focused research that addresses questions that affect the quality and perfor- mance of their sponsor’s pavement infrastructure positively through an improved quantification of risks associated with the use of various technologies, as well as improving the gen- eral understanding of material and pavement behavior and performance. EconomIc analysIs General Questionnaire Feedback on Economic Benefits Respondents indicated that the BCR is mostly used to evalu- ate the economic benefit of their programs. However, nine programs are not conducting economic evaluations, and most of the evaluations that are conducted are performed after the research has been completed (eight respondents) and not as an input in the research planning (four respondents). Feed- back from clients and sponsors are in some cases used to evaluate the benefit, albeit not in economical or objectively measured terms. The benefit of cost avoidance or avoidance of implementation of a costly action that is proven to be inef- fective during f-sAPT is also seen as a strong indicator of the success of some f-sAPT programs. Estimates of BCR from respondents (Figure 50) indicated that the majority (six respondents) estimate their BCR at between 1% and 5%. The number of respondents drops for the next two categories (6% to 10% and 11% to 20%) and increases again for the over 31% BCR group. chapter six Impacts and EconomIc analysIs

99 Background The evaluation of economic benefits of f-sAPT has been con- ducted for many years. Metcalf (1996) already mentioned attempts at calculating these benefits, whereas Hugo and Epps Martin (2004) expanded on these issues with the wider reporting of economic benefits during the late 1990s. Ben- efits not translated to economic numbers were also included in the latter. Much work has been conducted during the last decade with the 3rd APT conference using this as a theme, as well as various TRB sessions focusing on economic aspects. It appears that the general international economic conditions force researchers to prove the benefit of their research much more and identify, analyze, and quantify the direct and indi- rect benefits obtained from full-scale APT. Recent studies in the United States suggest that clear justifications of costs and benefits may increase public confidence in decision makers. The COST 347 study suggested that transparency and the 0 10 Im pro ve d s tru ctu ral de sig n m eth od s Im pro ve d m ate ria l d es ign m eth od s Ev alu ati on of no ve l m ate ria ls/s tru ctu res Im pro ve d p erf orm an ce m od elin g Pe rfo rm an ce -re lat ed sp ec ific ati on s Ma ter ial da tab as es Be tte r u nd ers tan din g o f va ria bili ty Im pro ve d p av em en t m an ag em en t Wa rra nty co ntr ac ts 20 30 40 50 60 70 N um be r o f r es po nd en ts FIGURE 49 Major benefits of f-sAPT. 0 1 2 3 4 5 6 7 1 to 5 6 to 10 11 to 20 21 and up N um be r o f r es po nd en ts Benefit Cost Ratio range [%] FIGURE 50 Estimates of BCR for f-sAPT facilities.

100 use of evaluation methods (such as cost-benefit analysis) may help increase funding by enhancing the marketing of research activities and results. Expanding global collabora- tion of transportation research would require establishment of evaluation techniques that are acceptable to all participat- ing agencies (Nokes et al. 2011). Du Plessis et al. (2008a) reported that, although signifi- cant technical breakthroughs have been made in the UCPRC full-scale program, the following questions remain: • What is the potential impact of the research results? • How much implementation has taken place? • What are the practical benefits obtained from the research program? Harvey (2008) stated that f-sAPT has been part of the devel- opment of new pavement technology for more than 60 years, offering unique capabilities to rapidly move pavement tech- nology through the various developmental levels to full-scale use at attractive BCRs. It also offers the ability to attract and focus attention on pavement problems and solutions, and the opportunity to focus thoughts and actions on future pavement requirements and demands (i.e., higher traffic volumes and less available natural materials). Lay (2006) stated that an “impediment in valuing research projects is the difficulty of convincing the researchers to take the valuation process seriously” and that it is “as if the researchers’ livelihoods did not depend on the value of their research output.” Sampson et al. (2008) found a key element associated with decreases in research funding to be the relatively high cost of research and development activities conducted in the road building sector. In addition, the impacts of these activities are often of a highly technical nature with the link between applied funding and the associated benefits not always obvi- ous. The lack of immediate, tangible benefits stemming from road-related research funding is a significant detriment when the motivation for funds has to compete with other budget demands such as those related to health and education, which have more immediate and obvious benefits. In an attempt to investigate and clarify the benefits associated with tech- nology development work in the road sector, the Gauteng Department of Public Transport, Roads and Works initiated a study to develop and execute an appropriate methodology for quantifying the benefits stemming from road-related research and development, with specific emphasis on their HVS tech- nology development program. Economic analysis approaches Various approaches exist for economic analysis of benefits of research investments (Du Plessis et al. 2011). Agencies typically use indicators such as the Net Present Value, Pres- ent Value of Benefits, Present Value of Costs, and BCR. The BCR is the approach primarily used and cited in full-scale APT literature. It is simply the quotient of total discounted benefits divided by total discounted costs, and projects with BCR of greater than one have positive net benefits with higher ratios translating into greater benefits relative to costs. Du Plessis et al. (2011) demonstrated a method initially developed and applied in Australia and later enhanced and applied in South Africa to determine economic benefits of f-sAPT programs. A key part of this process consists of esti- mating the probability of technical advances that would have occurred if the specific APT had not been performed. The process includes evaluation of alternative scenarios of tech- nology development through decision tree analysis taking uncertainty into account. The key elements of this methodol- ogy include the following main steps: • Identify the situation with and without the benefit of f-sAPT; • Accommodate the uncertainty in assumptions and out- comes by assigning a probability to each alternative outcome; • Calculate the life-cycle cost of each alternative outcome; • Calculate the expected value (cost) of each alternative outcome by multiplying its probability by its cost; • Calculate the total expected value for each decision (with f-sAPT and without f-sAPT) as the sum of expected cost for alternative outcomes; • Determine the benefit (in terms of cost savings) of the information provided by the f-sAPT by subtracting the total expected cost without the f-sAPT from the total expected cost with the f-sAPT included; and • Derive the BCR by dividing the benefit by the total costs of the f-sAPT. Nokes et al. (2011) stated that research project life cycles are long, monetary benefits that only accumulate late in the process and lead responsibilities to change in successive phases of the project. The eventual accumulation of benefits requires continuing actions by implementers not associated with the original research. It is accepted that agency cost savings diminish gradually over a time horizon such as 5 to 10 years, and retrospective assessment of benefits of research should wait until most or all cost savings have accumulated. Analysts who evaluate research benefits must decide what is significant to be measured, how and when to measure, and then how to interpret the results. Many impacts are difficult to quantify. F-sAPT researchers and operators might con- sider the following needs and potential ways to pursue them regarding economic evaluation of f-sAPT programs: • Recognize the need for more frequent, formal, and quan- titative assessments of f-sAPT research; • Organize and perform coordinated studies of evaluation techniques for f-sAPT research; • Investigate techniques that may be suitable for both ret- rospective and prospective assessments;

101 1. Conceptual and time-related separation between proj- ect findings and benefit realization, 2. Benefits often resulting from several contributing proj- ects and processes, and 3. Benefit assessment involving a significant subjective component. A survey of the technical impacts of road-related technol- ogy development work, and specifically of those involving f-sAPT, showed that the technical impacts of road-related technology development work can be generalized into the following three categories: 1. Optimized materials and pavement design, which lead to reduced construction costs; 2. More reliable design and maintenance practices that reduce the likelihood of costly early failures; and 3. More cost-effective materials and pavement design that optimizes the time between maintenance interven- tions and reduces pavement life-cycle costs. Direct economic benefits that are typically derived from these impacts can be evaluated in different ways. The approach described by Sampson et al. (2008) compares the life-cycle costs of viable scenarios with and without the benefit of the impacts that stem from technology development work. The approach includes the following steps: 1. The life-cycle cost for constructing and maintaining a typical road segment is calculated for scenarios with and without the benefits of technology development work. 2. A probability of occurrence is assigned to each scenario (an indication of the average long-term, network-wide likelihood of occurrence for each scenario). 3. The two life-cycle costs calculated in Step 1 are mul- tiplied by the probabilities assigned in Step 2 and the difference between the two products calculated. This is the net benefit per road segment. 4. The net benefit per road segment is multiplied by the size of the network on which the technology develop- ment will have an impact. This provides an indication of the overall network-wide savings associated with the impact of the technology development work. 5. The overall savings calculated in Step 4 is the expected long-term benefit assigned to a specific impact stem- ming from technology development work. A key aspect of the process used by Jooste and Samp- son (2004) is that it relies on documented interviews with individuals involved in the implementation and use of the technology. These interviews form the basis for the critical subjective assumptions and lend consistency and credibility to the approach. Examples and applications Gillen et al. (2001) presented the evaluation of the economic costs and benefits of implementation of three recommenda- • Evaluate previous and existing efforts at establishing frameworks to evaluate research benefits; • Pursue and promote systematic and consistent practices for evaluating f-sAPT research results; • Identify conditions and criteria for assessing f-sAPT at various levels of assessment; • Investigate the potential development of a multifac- eted approach that combines many techniques and mea- sures that complement each other and may be suitable for f-sAPT research as well as other pavement and/or transportation research; • Develop standardized and commonly accepted (between f-sAPT programs) techniques and measures for estab- lishing and evaluating costs and benefits of f-sAPT research; and • Identify credible evaluation techniques that potentially are acceptable to international agencies. In a study by Nokes et al. (2011) to determine direct eco- nomic benefits of f-sAPT using HVSs in California, it was found that the Australian/South African technique provides advantages such as quantitative, direct economic benefits (benefit/cost generally under 10:1), analysis of alternative outcome scenarios accounting for uncertainty, and validation interviews with implementers of research findings. Chal- lenges identified in using this methodology include intensive cost, labor, and time requirements, as well as sensitivity to assumptions and subjective input. In general, the quantification of benefits centers around the assumption of new and freely available information that will impact positively on policies, which, in turn, lead to measurable economic benefits (Sampson et al. 2008). This simple linear model fails to adequately take into account the complex relationships between development, innova- tion, and government policy objectives. The failure of a simple benefit quantification to take into account further downstream benefits and the impact of these on the quality of life of the population at large means that the benefits of publicly funded technology development are likely to be greatly underestimated. In an effort to provide a more accurate assessment of the benefits of technology develop- ment work, the use of direct (benefits that rely primarily on the project outcomes) and indirect (benefits that arise because of the development process) benefits should be considered. Although indirect benefits such as the number of employ- ment opportunities created and technical progress are impor- tant, it can be argued that at the strategic level a favorable economic indicator such as a BCR provides a more power- ful motivation for continued technology development fund- ing. Quantified estimates of the direct economic benefits arising from technology development work are difficult to obtain because of the vague and subjective nature of the task. Among the many difficulties associated with such a benefit assessment are the following three aspects:

102 Du Plessis et al. (2008b) concluded that their Austra- lian/South African method is effective in identifying the implementation of results from HVS tests, identifying practical benefits and quantitatively determining impacts of HVS research, proving that Caltrans’ investment in f-sAPT research with the HVS has been rewarding and well worthwhile. Du Plessis et al. (2011) conducted a case study applying the Australian/South African method to HVS tests conducted for Caltrans. The case study evaluated benefits from HVS tests performed to validate innovative pavement mixes and designs proposed for the rehabilitation of a high traffic urban interstate route. Although local conditions differ significantly between these countries the method was successfully applied and showed positive results. In addition, there are a number of other qualitative ben- efits from HVS testing that are difficult to quantify, such as peripheral software development and the generation of new knowledge that can be applied elsewhere (Du Plessis et al. 2008b). ranges of Values Based on the questionnaire feedback and current literature, the ranges of BCRs are shown in Table 38. It is important to ensure that the same factors had been included in analyses compared with each other and that similar analysis proce- dures have been applied. The data in Table 38 indicates that the ranges are broadly between 1.4 and 11.6 (excluding the high Caltrans example where user costs were included in the analysis). This relates well with the 10 respondents who indicated a BCR of between 1 and 10 for their facilities (see Figure 50). Du Plessis et al. (2008a) calculated BCRs ranging from 3.2 to 9.5 in analyses of UCPRC APT projects. These val- ues are deemed very conservative because they do not take into account indirect benefits, savings in user delay costs and accident costs and cost avoidance. Du Plessis et al. (2011) compared various f-sAPT evaluations and BCR values for a discount rate of 4% reported in the Australian, South African, tions for changes in flexible pavement design and construc- tion made by University of California Accelerated Pavement Testing pavement research program to Caltrans. The anal- ysis was performed using a full-cost model developed for transportation projects including direct agency costs, user costs, and safety costs. It was shown that new pavement technologies (primarily consisting of the method of appli- cation of pavement materials) can deliver significant cost savings to Caltrans maintenance and rehabilitation efforts. Caltrans used a life-cycle costing model to minimize the sum of capital and maintenance costs. In calculating future maintenance costs, Caltrans considers the direct costs to the agency through contracts, and attempts to consider the impact on traffic flow, but not safety and the environment. The first two components reflect the conventional life-cycle cost model; however, user costs are not considered by many agen- cies. Once all user costs over the lifetime of the facility are taken into account, the standard to which a facility is built and the frequency of repair and rehabilitation will change. The new pavement technologies reviewed and evaluated in this research provide a means of reducing all costs, including those directly incurred by Caltrans and those incurred by users and the pub- lic. Implementing the recommended increase of the period between overlays by 1.5 years resulted in savings of more than $56 million. If the period between overlays is extended by 5 years, the statewide savings is more than $244 million (these savings exclude user and safety cost savings). King and Morvant (2004) evaluated the Louisiana APT program and the BCR assessment of the implementation strat- egies for the first three experiments conducted since 1993. Results indicated that the BCR over the period (2001–2003) was 5.3. The life-cycle savings for two implemented sections evaluated was 40%. Implementation of the information from this experiment has proven to be very beneficial to the Louisi- ana Department of Transportation and Development. Through the BCR procedure Louisiana has proven that implementing research sections from APT testing on the nation’s highways can save the motoring public both money and time. MnROAD has led to positive economic benefits during its initial research phase (Worel et al. 2008). The Phase I research benefited Minnesota by providing insight into poli- cies resulting in increased pavement life. Some of these areas include seasonal load policies, M-E design methods, HMA binder gradation, low temperature cracking reduction, and improved pavement maintenance operations. These benefits led to an annual savings for MnDOT of at least $33 million for six projects evaluated. Other benefits are equally impor- tant but harder to quantify. Neither national nor local pri- vately owned pavements were included in the cost savings even though they also gain a benefit through the research findings and updated construction specifications. MnROAD Phase I (1994–2006) costs were estimated at $44 million and its benefits at $396 million [$33 million per year for six research findings over a 12-year period (2006–2012)], repre- senting a BCR of 8.9. Origin BCR UCPRC 1 3.2 to 9.5 Australia 1.4 to 11.6 South Africa 2.2 to 10.2 Caltrans I710 5.3 and 32.4 Louisiana 5.3 MnROAD 8.9 TABLE 38 SUMMARy OF BENEFIT COST RATIOS (BCRS) FROM QUESTIONNAIRE AND LITERATURE

103 decade as a combination of contributions to national and local guidelines and specifications, opportunities and fund- ing for academic graduate studies, and subsequent fast-track of knowledge implementation, the validation of analytical design standards, and acceptance by industry of technologies proven through f-sAPT. A highly significant benefit of f-sAPT programs is the opportunity these programs create for staff training and learning. Pavement engineering represents only a small pro- portion of the curriculum at most tertiary engineering edu- cation institutions, and it is widely recognized that there is a current global shortage of skilled pavement engineers. Moffat et al. (2008) described how the Australian operation of ALF has exposed student and graduate engineers to a wide range of learning experiences, including pavement construc- tion, instrumentation, condition measurement, laboratory testing, analysis, and report writing. An f-sAPT facility and associated research program can cre- ate an excellent environment for staff training and increased learning. Rust et al. (1997) described the educational benefit of the long-running and extensive HVS program in South Africa. They noted that pavement engineers who have seen an f-sAPT in operation have an insight not afforded other engineers that may only rarely see badly failed pavements, and then without the benefit of truly knowing the contri b- uting conditions. These assertions are echoed by many pavement engineers, clients, and researchers in South Africa and the United States during discussions on training and education. Engineers exposed to f-sAPT programs are typically exposed to activities such as pavement terminol- ogy and the roles of materials within pavement structures, removal of existing pavements layers, pavement construc- tion and surfacing, construction-related testing, quality control and assessment, laboratory testing, and in situ field testing (i.e., FWD). Although many of these activities are commonly con- ducted throughout the road industry, it is considered uncommon for a recent engineering graduate to be exposed to such a range activities within the first 12 months of a pro- fessional career (Moffat et al. 2008). Engineers also gained experience and skill in specialist areas such as the measure- ment of pavement responses to load using strain gauges, pavement trenching, and related investigations and technical and the Californian cost-benefit studies on their respective APT devices revealed the following: • The Australian ALF program reported a BCR of 4.9 for the overall APT program and BCR values of between 1.4 and 11.6 for individual ALF tests. • The South African HVS study on the G1 base course technology reported BCR values of between 2.2 and 5.6 (low contribution ratio) and 3.6 and 10.2 (high con- tribution ratio). • The California I-710 HVS tests: BCR values of between 5.3 and 7.1 (low contribution ratio) and 22.4 and 32.4 (high contribution ratio). Although the California studies have a larger spread of BCR values, these results are in agreement with the other two f-sAPT programs (road user costs were included in the Californian study as opposed to only agency costs in the Australian and South African studies) (Du Plessis et al. 2011). The credibility of this type of analysis lies in the acceptance of the results by road authorities and practitio- ners. One of the criticisms of BCR is the effect of inputs, assumptions and subjectivity on results as reflected in the sensitivity analysis. A sensitivity analysis is recommended as it enables examination of these effects for interpretation and use of BCR values. EducatIonal BEnEFIts oF accElEratEd paVEmEnt tEstInG Ten respondents indicated that f-sAPT data are used for grad- uate studies on selected projects, whereas five respondents indicated this to be the case for all projects. Table 39 shows that 32 degrees linked to f-sAPT data were completed in the last decade, while an additional 23 degrees of current stu- dents will be linked to f-sAPT data (linked indicates that the studies have at least made use of data from f-sAPT programs, whether or not specific new tests have been conducted for the specific degree). A listing of references to specific masters and doctorate degrees (provided by questionnaire respon- dents) linked to f-sAPT is provided as a separate part of the bibliography. References could not be obtained for all the degrees indicated in Table 39. Respondents evaluated the major influence that their f-sAPT programs had on academia and industry over the past TABLE 39 DEGREES COMPLETED PARTLy OR FULLy BASED ON f-sAPT DATA BETWEEN 2000 AND 2010 Degree Type Completed Current Links to Theses Total Masters 15 8 2 25 Doctorate 15 9 3 27 Other 2 1 0 3

104 chaptEr summary This chapter evaluated the impacts and economic benefits of f-sAPT. Major impacts are viewed as improved understand- ing of pavement materials, structure, and general performance and behavior. The economic benefit of f-sAPT programs can be calculated objectively, and most facilities either calculate or assume BCRs of between 1 and 10. It appears as if BCR evaluations are being done by more f-sAPT owners over the last several years, although it still often happens after the testing and not as part of the planning process. The educa- tional benefits of f-sAPT lie in the opportunity of providing students and young engineers with the funding, topics, and technical support to pursue studies in pavement engineering through detailed analyses of full-scale pavement behavior. At least 55 specific students could be identified as involved with graduate studies linked to f-sAPT in the past decade. photo graphy. It also provides an excellent environment for developing skills in project management, technical writing, and communication. Within the specific research teams engineers are working they are exposed to detailed discus- sions on pavement performance and behavior and learn to evaluate a pavement’s condition from various angles, allowing young engineers to develop a feel for pavement behavior. Tompkins et al. (2008) evaluated various benefits of the MnROAD project and concluded that one of the benefits (among many others) was the opportunity for collabora- tion on the state, local, and federal levels in the study of pavement and pavement technologies with the result of an increase in the general level of technical understanding of pavement engineers in the state based on their exposure to this facility.