Performance Specifications for Rapid Highway Renewal (2014)

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19 C h a p t e r 3 This chapter presents the general findings from the R07 research effort to develop and implement performance speci- fications. The discussions primarily focus on addressing the following points: • How the performance specification framework introduced in Chapter 2 was applied to each of the research areas; • What benefits and risks are associated with performance specifying; and • What conditions or characteristics tend to make a project an ideal candidate for using performance specifications. performance Specifications The performance specification framework introduced in Chapter 2 was applied to each of the research areas to pro- duce guide performance specifications capable of promoting rapid renewal. For each research area, the team summarized the current state of performance specifying on the basis of a review of the literature as well as expert opinions obtained through workshops with representatives from agencies and industry. The summaries address how the guide specifica- tions attempt to advance the state of the practice and what additional developments would be necessary for the specifi- cations to evolve further. As applicable, the team addressed demonstration projects in the context of identifying lessons learned and opportunities for further advancement of the current guide specifications. Notably, both the state of the practice and opportunities for further advancement are highly dependent on the subject matter. For example, application of performance specifica- tions is more evolved and prevalent for pavements than for the other discipline areas considered in the research, such as bridges and geotechnical features. Concrete Pavement State of the Practice in Performance Specifications Much of the research and debate related to performance speci- fying for concrete pavement has focused on the application of quality- or performance-related pay adjustment systems. As summarized here, two general approaches have emerged. One, as promoted in current quality assurance (QA) specifications, involves statistically based sampling and testing plans that consider the measured variability of the product to determine pay factors. The other entails the use of predictive models to assign more rational pay adjustments on the basis of the dif- ference between the as-designed and as-constructed life-cycle cost (LCC) of the pavement. StatiStically BaSed SpecificationS. Statistically based accep- tance plans and pay adjustment systems have been widely applied to concrete pavement construction. However, many of the properties emphasized in current specifications do not necessarily reflect performance. Properties related to concrete durability (e.g., air quality, permeability, unit weight, steel placement, thickness, and mix uniformity) can be more criti- cal to pavement performance than strength, yet they are often excluded from acceptance plans. Commonly used acceptance quality characteristics (AQC) include compressive strength, thickness, and smoothness. (Agencies concerned with freeze–thaw resistance also often use air content as a screening test before concrete placement but not as a pay factor.) Agencies differ on the methods and weights used to com- bine pay factors, with most relying on experience and engi- neering judgment to establish a composite pay factor (CPF) equation. The following equation from NCHRP 10-79 syn- thesizes the various pay equations reportedly being used by Findings

20 departments of transportation across the country (Hughes et al. 2011): CPF 0.25 PF 0.35 PF 0.40 PFstrength thickness smoothness( ) ( ) ( )= + + performance-related SpecificationS. Much of the more performance-oriented research in the concrete pavement area has focused on the development of performance-related speci- fications (PRS) that use mathematical models to predict future performance on the basis of select quality characteristics mea- sured at the end of construction. PRS are often referred to as the next generation of QA specifications, because they attempt to use predictive models to assign rational pay adjustments on the basis of the difference between the as-designed and as-constructed life-cycle cost of the pavement. The basic premise behind PRS methodology is that lower or more variable quality levels will result in reduced pave- ment performance, requiring an agency to incur maintenance and rehabilitation expenditures sooner and more frequently than would otherwise be the case. By using bonuses or penal- ties to pass the expected consequences of particularly good or bad construction quality onto the contractor, a more rational acceptance and payment methodology can be achieved (Hoerner and Darter 1999a). PRS have been fully implemented on select projects in Indi- ana, Florida, California, Tennessee, and Wisconsin (Hoerner and Darter 1999b; Evans et al. 2005; Rao et al. 2007; Evans et al. 2008). Other states, including Iowa, New Mexico, and Kansas, have demonstrated PRS as a “shadow” specification (that is, results did not affect contractor pay). The PRS for these projects were developed using PaveSpec 3.0 software, which supports pay adjustments for the follow- ing AQCs (Hoerner et al. 2000a, 2000b): • Concrete strength (either compressive or flexural, depend- ing on normal agency practice); • Slab thickness; • Initial smoothness; and • Entrained air content. The software also allows use of Percent Consolidation Around Dowels as an acceptance parameter. However, it has not been used in any portland cement concrete (PCC) pavement PRS to date, presumably because of the difficulty of measuring that property in the field. One important feature of the PaveSpec software is that it allows users to adjust calibration factors and coefficients to reflect the agency’s actual experience. While this methodology and software provide a sound process for developing PRS, the software does have some limitations, including the following: • The software considers only jointed plain concrete pave- ment (JPCP) and not continuously reinforced concrete pavement (CRCP) or jointed reinforced concrete pave- ment (JRCP). • Performance prediction models consider only transverse joint faulting, transverse fatigue cracking, transverse spall- ing, and roughness progression/international roughness index (IRI). Work is under way to finalize and pilot PaveSpec version 4.0 software, which will incorporate the latest Mechanistic– Empirical Pavement Design Guide (MEPDG) JPCP models and support a more comprehensive set of AQCs. However, some of the limitations seen with the current software will still remain: • Pay factors are independent (i.e., interaction between AQCs is not explicitly considered in the simulation). • Models do not address durability, longitudinal cracking, and other long-term distresses. Ideally, PRS will evolve to incorporate all of the important AQCs of PCC pavement that not only affect performance but are also under the contractor’s control. Incorporation of more robust mechanistic-empirical models, such as those developed for and used in mechanistic-empirical design pro- cedures, may enhance the current PRS methodology. But it will not eliminate the challenge of how to tie design assump- tions to actual field data and acceptance tests. Achieving the ideal PRS will require advances in non- destructive sampling and testing and improved understand- ing of long-term material behavior. FHWA-RD-98-155 defines the various stages of PRS implementation as follows (Hoerner and Darter 1999a): • Level 1 or “Simplified” PRS use standard agency monitor- ing and testing practices as much as possible. Independent pay factors are developed for each AQC and then com- bined manually through a composite pay factor equation. The PRS that have been implemented to date are consid- ered Level 1 PRS. • Level 2 or “Transitional” PRS seek to better quantify future performance by comparing as-designed and as-constructed LCCs. The Level 2 PRS encourage use of more in situ and nondestructive sampling and testing. The pay schedules developed under a Level 2 PRS consider the interaction of the various AQCs to directly compute a pay factor through computer simulation. • Level 3 or “Ideal” PRS will consider as many AQCs as pos- sible in the LCC evaluation and will use only nondestruc- tive, in situ testing to measure those AQCs. Many issues need to be addressed before Level 3 PRS can be achieved, such as development of new test methods and identifica- tion of all critical AQCs.

21 Warranty proviSionS. Moving beyond QA and PRS specifica- tions, warranty provisions have also been applied to PCC pavements to address actual performance over time. One of the advantages of a warranty specification is the ability to cover certain types of distresses and functional characteristics that would be difficult to address using predictive models. For example, corner cracking, deterioration cracking or material- related distress, popouts, texture loss, scaling, and sealant damage or loss are some of the distresses commonly found in warranty provisions for PCC pavement. Warranties can also address certain functional characteristics that would be diffi- cult to predict using mathematical models, such as texture or texture loss and skid resistance. Warranties have not been as widely applied to PCC pavement as they have to hot-mix asphalt (HMA). Warranties can be suc- cessful in protecting against premature failure (i.e., ensuring that distresses resulting from materials and workmanship— such as plastic shrinkage cracking and surface deterioration or scaling—are corrected). But they do not serve as effective guar- antees of long-term performance. Concrete pavements tend to fail in a nonlinear fashion, with deterioration occurring rapidly after some threshold point in the pavement life, which generally occurs well beyond the 5-year duration of most short-term warranties. To successfully ensure long-term performance, the warranty period would have to be long enough to allow indica- tors of long-term performance issues to appear within the war- ranty period such that future problems could be averted through corrective action. Unfortunately, difficulties in obtain- ing bonds have generally precluded long-term warranties. Higher-level performance parameters directly addressing user needs (e.g., comfort, safety, accessibility, and so on) have primarily been implemented for pavements only under longer- term design-build-operate-maintain (DBOM) contracts. The more progressive of these specifications attempt to view the pavement and underlying soil layers as an integrated system, more akin to how the traveling public views a roadway. Such specifications promote a paradigm shift in how pavements are designed and constructed (e.g., by allowing developers to adjust their pavement design based on the as-constructed sub- grade conditions). Guide Specifications caSt-in-place concrete pavement. The R07 research team drafted a family of guide performance specifications for PCC pavement. The specifications were drafted with a specific delivery approach in mind; that is, the recommended perfor- mance parameters and materials and construction require- ments included in each specification are tied to the roles and responsibilities and risk allocation deemed appropriate for a design-bid-build (DBB), design-build (DB), warranty, or design-build-operate-maintain (DBOM) project. To advance the state of practice under the DBB and DB cases, the guide specifications attempt to incorporate quality management and acceptance criteria that more closely corre- late to durability. The overall objective of these specifications is generally consistent with the statistically based acceptance procedures and pay factor adjustments found in current QA and PRS specifications. The specifications have therefore been structured to both complement existing practice when possi- ble and highlight (through provided commentary) when a different approach may be necessary or beneficial to advance the goals of rapid renewal. To promote rapid renewal, the guide specifications • Emphasize properties known to affect durability, such as air quality, permeability, unit weight, steel placement, joint conditions, thickness uniformity, and mix uniformity; • Recommend test methods that are more conducive to rapid renewal, such as maturity meters and thickness probes; • Encourage contractors to use tools, such as HIPERPAV (HIgh PERformance concrete PAVing) software, stringless paving, and real-time smoothness devices, to improve workmanship process control; • Promote the use of NDT devices, such as ground penetrat- ing radar and magnetic imaging tomography, which reduce the need for destructive core samples; and • Incorporate financial incentives/disincentives to promote enhanced quality or durability. Even with recent advancements in mechanistic-empirical design procedures and nondestructive evaluation (NDE) meth- ods, current gaps in knowledge and modeling and testing tech- niques suggest that, in the near term, performance specifications implemented under DBB or DB will likely retain some prescrip- tive elements or surrogate properties to ensure equitable risk allocation between the agency and the contractor. More freedom can be extended to the contractor under warranty and maintenance provisions containing functional performance parameters that monitor and evaluate the actual performance of the pavement over time. However, organiza- tional and industry-related issues may make it difficult for an agency to immediately assign postconstruction responsibili- ties to industry. Additional training, guidance, and mentor- ing will likely be needed before responsibility and control of performance can be shifted from agency to industry staff. On the one hand, this may involve retraining agency staff to “step back,” not prescribe how to perform the work, and adopt more of an oversight role to ensure that performance targets are met. On the other hand, industry may need to invest in the tools and training to take on greater responsibility for the entire project life cycle, including design, construction, and long-term performance. The executive guide addresses orga- nizational and industry considerations related to implement- ing performance specifications.

22 Recognizing such technological and business-related chal- lenges to the advancement of performance specifications, the guide specifications incorporate a tiered implementation approach. This approach balances a project’s needs and goals against available technology and resources, the capabilities of local industry (including materials suppliers and testing firms), associated costs, and industry’s appetite for assuming perfor- mance risk. The tiers generally represent a progression from minimal departure from current practice to a substantial shift in practice and organizational culture. The latter would require technological advancement, improved understanding of long- term material behavior, and possibly a new business model. • Tier 1 requirements do not require a substantial departure from current practice, yet they place more emphasis on prop- erties known to affect performance (e.g., air content) and encourage the use of NDT techniques (e.g., maturity meters and thickness probes) as a rapid renewal consideration. • Tier 2 requirements incorporate more performance-oriented parameters (e.g., permeability and air quality), for which test methods may be currently available but which would require further advancement or refinement to provide the repeat- ability and accuracy needed for acceptance purposes. To implement other Tier 2 requirements, contractors may need to make some investment to acquire the neces- sary knowledge, skills, and equipment to fulfill their obliga- tions under a performance specification without passing on excessive risk pricing to the agency. For example, if noise reduction is an agency goal, a functional parameter could be developed based on the noise generated from pavement- tire interaction, as measured using onboard sound intensity (OBSI) techniques. However, until industry gains sufficient understanding of how to modify its standard means and methods to meet a certain decibel level, simply using a pre- scriptive texturing specification to accomplish the same objective may be more cost-effective. • Tier 3 requirements assume improved understanding of long-term material behavior as well as advances in tech- nology, particularly in the area of NDT technology. Such advances could permit the inclusion of acceptance param- eters that better reflect the future performance and design life of the pavement. Figure 3.1 summarizes the three tiers and the motivations for implementing each. Although the figure suggests a time frame for implementation, to some extent, this will be agency specific. For example, warranty provisions and long-term DBOM agreements may fall into the Tier 2 and Tier 3 catego- ries, respectively, among agencies that first have to foster the necessary internal and external support for assigning such postconstruction requirements to industry. Some agencies, however, have already implemented such specifications and can provide a roadmap for agencies interested in pursuing a similar program. Tables 3.1 through 3.3 summarize the suggested perfor- mance specification strategy for each of the tiers. To help deter- mine the appropriate tier, users should consider what would best fit the needs of their particular project or program, bear- ing in mind that possible barriers or gaps may preclude the immediate implementation of all of the proposed parameters and test methods. For example, some agencies may have diffi- culty implementing even an “immediately implementable” Tier 1 parameter if they lack the historical data needed to assign reasonable thresholds and targets. An effort to document or showcase the experience of agencies that are already using Tier 1 parameters would further promote implementation. precaSt concrete pavement. Modular pavement technology is a relatively new method for pavement construction. How- ever, with the implementation of precast concrete pavements (PCP) in dozens of states and for hundreds of lane-miles of pavement, it is now recognized as a mature and no-longer- experimental technology. Although typically more costly than cast-in-place pavement, precast systems offer a viable solution for rapid renewal that can be deployed during short lane closures, minimizing disruption to the traveling public. To help increase the comfort level with modular pavement technology, the R07 team prepared a guide performance specification focusing on PCP. It highlights the requirements that have been determined to be most critical for the success- ful use of this technology. Much of the specification content was developed under the SHRP 2 R05 project, which specifi- cally focused on development of modular pavement guid- ance and specifications for rapid renewal (Tayabji et al. 2012). Although the guide specification focuses on precast systems, it can also serve as a template for specifying other modular systems addressed by the R05 project, such as rollable asphalt. The R07 team tailored the R05 recommendations to a per- formance specification framework. The result was a specifi- cation that promotes competition among different precast systems and incorporates many of the functional perfor- mance parameters, such as ride quality, that are important to road users and are commonly applied to conventional con- crete pavements. A key component of the guide specification, described in greater detail in the R05 effort, is the system approval and trial installation process (Tayabji et al. 2012). A number of proprietary PCP systems are currently available and proven for PCP construction. These systems typically use patent- protected components and details for fabrication and instal- lation of the precast panels. While such systems should not be precluded from use, agencies are typically unable to specify a sole-source proprietary product for use on a project unless no other comparable alternatives are available. Similar to a

23 Figure 3.1. Implementation tiers for PCC pavement. Table 3.1. PCC Pavement, Tier 1 Summary Motivation Contractor Quality Management Acceptance Implementation Issues Differences from Current Practice Tier 1 Existing Specs and Practices • Place more emphasis on properties known to affect durability. • Use test meth- ods that are more conducive to rapid renewal. Quality Control Fresh Concrete: • Unit weight • Slump • Air content (by pressure test) • Placement temperature • Evaporation rate • Thickness (by probing) Hardened Concrete: • Strength (by maturity) Construction Acceptance • Surface distress • Thickness (by probing) • Strength (by maturity method) • Hardened air content • Ride quality • Joint deficiencies (visual) If using the existing PRS model as a basis for rational payment adjustments, PaveSpec 3.0 simulation software supports pay adjustments for the fol- lowing quality characteristics: • Strength • Thickness • Initial smoothness • Entrained air content • Percent consolidation around dowels • Some additional funds for testing will be needed. If using the existing PRS model as a basis for ratio- nal payment adjustments, additional issues may include the following: • DOT and industry accep- tance of predictive model will be needed. • A database of local mea- surement values needs to be developed. • Not all factors that could affect performance are considered in the existing PRS simulation software (PaveSpec 3.0). • Measure unit weight as part of process control. (This will help ensure that the mix that is poured meets the mix design.) • Reduce impor- tance of strength as an acceptance parameter. • As a rapid renewal consideration, use maturity method to estimate in-place concrete strength.

24 Table 3.2. PCC Pavement, Tier 2 Summary Motivation Contractor Quality Management Acceptance Implementation Issues Differences from Current Practice Tier 2A Performance- Oriented Testing • Place more emphasis on properties known to affect pavement performance. Quality Control Fresh Concrete: • Unit weight • Slump • Air quality (by AVA) • Placement temperature • Evaporation rate • Thickness (by probing) Hardened Concrete: • Strength (by maturity) • Permeability Workmanship Process Control • HIPERPAV software • Stringless paving Construction Acceptance • Surface distress • Thickness (by MIT Scan T2) • Strength (by maturity method) • Air quality (by AVA) • Ride quality • Permeability testing (by chloride ion penetration resistance) • Joint deficiencies • Load transfer efficiency (by FWD) • Tire-pavement noise (OBSI) • Additional funds for testing will be needed. • Training and more advanced skills will be required. • The chloride ion permeability test is more representative of bridge decks than pavements. • Measure addi- tional properties that are more performance- oriented (e.g., permeability, tire- pavement noise). • Measure proper- ties using tech- niques that are more indicative of performance (e.g., AVA). • Incorporate use of nondestructive evaluation techniques. Tier 2B Short-Term Warranty • Protect against early failure. • Open up require- ments affecting short-term design life or materials close to the surface. Quality Control Fresh Concrete: • Unit weight • Slump • Air quality (by AVA) • Placement temperature • Evaporation rate • Thickness (by probing) Hardened Concrete: • Strength (by maturity) • Permeability Workmanship Process Control • HIPERPAV software • Stringless paving Construction Acceptance • Surface distress • Thickness (by probing) • Strength (by maturity method) • Air quality (by AVA) • Ride quality • Joint deficiencies • Load transfer efficiency (by FWD) • Permeability (by chloride ion penetration resistance) • Tire-pavement noise • Skid resistance Postconstruction Acceptance • Ride quality (IRI) • Skid resistance • Cracking • Surface defects • Potential institu- tional, legal, and organizational barri- ers will need to be overcome. • Additional agency monitoring and test- ing post construction will be needed. • Reasonable thres- holds based on the duration of pave- ment warranty and maintenance agree- ments will need to be set. • Provide less agency oversight and testing dur- ing construction. • Make no payment adjustments at the end of construction. • Emphasize post- construction monitoring. Note: FWD = falling weight deflectometer; AVA = air void analyzer; MIT = magnetic imaging technology; OBSI = onboard sound intensity; IRI = international roughness index. list of preapproved products that an agency may create for a particular material to be used during construction, the sys- tem approval and trial installation process provides a method for vetting and approving the use of PCP systems, whether proprietary or not. Contractors will be able to submit virtu- ally any PCP system for use so long as it meets the require- ments of the system approval and trial installation process. Asphalt Pavement State of the Practice in Performance Specifications Similar to PCC, asphalt performance has been the subject of numerous research studies over the years. That research has supported the progression of asphalt pavement specifications from predominantly method statements to the end-result and statistically based QA requirements prevalent in current standard pavement specifications. Warranties have also been commonly applied to HMA pavement. A methodology for creating PRS for HMA has been developed, but it remains in the validation stage. StatiStically BaSed SpecificationS. Statistically based accep- tance plans—following a percent within limits (PWL) approach—and pay adjustment systems have been widely applied to asphalt pavement construction. AQCs for HMA are often separated into materials and construction categories. Acceptance of materials is normally based on plant-tested sam- ples, while acceptance of construction is based on field samples.

25 Table 3.3. PCC Pavement, Tier 3 Summary Motivation Contractor Quality Management Acceptance Implementation Issues Differences from Current Practice Tier 3A Performance-Oriented Testing • Incorporate parame- ters and test methods that are more indica- tive of pavement performance. Quality Control Fresh Concrete: • Unit weight • Slump • Air quality (by AVA) • Placement temperature • Evaporation rate • Thickness (by probing) Hardened Concrete: • Strength (by maturity) • Permeability Workmanship Process Control • HIPERPAV software • Stringless paving • Real-time smoothness Construction Acceptance • Surface distress • Thickness (by MIT Scan T2) • Strength (by maturity method) • Air quality (by AVA) • Ride quality • Permeability (oxygen permeability index) • Joint deficiencies • Load transfer effi- ciency (by FWD) • Tire-pavement noise • Skid resistance • Dowel bar alignment (MIT Scan or GPR) • Steel location (GPR or MIT Scan) • Additional agency funds for testing will be needed. • Training and more advanced skills will be required. • Measure addi- tional properties that are more performance ori- ented (skid resistance). • Measure proper- ties using tech- niques that are more indicative of performance (e.g., oxygen per- meability index). Tier 3B Performance Warranty or DBOM • Reduce oversight during construction. • Open up design and material requirements affecting design life. Quality Control • Submit QMP Construction Acceptance • Conformance with design, QMP, and per- formance requirements Postconstruction Acceptance • Ride quality (IRI) • Cracking • Surface defects • Skid resistance • Structural integrity • Only P3s or long-term concession agree- ments will work. • Potential institutional, legal, and organiza- tional barriers will have to be overcome. • Pay adjustment sys- tems will have to be administered, and contractor perfor- mance self-reporting will have to be monitored. • Reasonable thresholds will have to be set. • Appropriate handback criteria will have to be identified. • Adaptation to changes in technology will be necessary over time. • Shift complete performance risk to the contractor. • Monitor actual performance over time. • Emphasize post- construction performance monitoring, with less over- sight during construction. Tier 3C Measurement of Mechanistic Properties • Improve understand- ing of performance (measuring design input values). Quality Control Fresh Concrete: • Unit weight • Slump • Air quality • Placement temperature • Evaporation rate • Thickness (by probing) Hardened Concrete: • Strength (by maturity) • Permeability Construction Acceptance • As-built conditions meet as-designed • A database of mecha- nistic properties will have to be built for inclusion in and refine- ment of MEPDG. • DOT and industry acceptance of predic- tive models will be needed. • Incorporate as- built materials properties and construction conditions into mechanistic design models to predict perfor- mance and adjust pay. Note: AVA = air void analyzer; GPR = ground-penetrating radar; QMP = quality management plan; P3 = public-private partnership; MEPDG = Mechanistic–Empirical Pavement Design Guide.

26 Commonly used materials AQCs include asphalt content, lab compacted air voids, and voids in mineral aggregate (VMA). Commonly used construction AQCs include density, thickness, and ride quality. Agencies differ on the methods and weights they use to combine pay factors; most rely on experience and engineer- ing judgment to establish a composite pay factor equation. AASHTO R 42, Standard Practice for Developing a Quality Assurance Plan for Hot-Mix Asphalt, suggests the following pay factor equation: CPF 0.35 PF 0.20 PF 0.35 PF 0.10 PF density asphalt content air void VMA ( ) ( ) ( ) ( ) = + + + performance related SpecificationS. In the mid to late 1990s, a major effort was undertaken to develop PRS for HMA pave- ments through the full-scale accelerated load testing at the WesTrack project in Nevada (Epps et al. 2002). The intent of WesTrack was to examine how deviations in materials and con- struction properties (e.g., asphalt content and degree of com- paction) affect long-term pavement performance, so that true PRS and PRS software could be developed for HMA construc- tion. The project was also intended to provide early validation of the Superpave volumetric mixture design procedure devel- oped through the original SHRP program. The AQCs consid- ered in the WesTrack experiment were HMA surface layer thickness, initial smoothness, asphalt content, air void content, and an aggregate gradation parameter (percentage passing the No. 200 sieve). The primary distresses monitored during the experiment were permanent deformation (rutting), fatigue cracking, and friction loss. The pavement sections constructed at WesTrack per- formed as expected in terms of the response of the different sections to changes in asphalt content and in-place density. But some unexpected results were also encountered: coarse mixtures, contrary to experience, were the most sensitive to asphalt content and in-place density. Forensic investigations of this phenomenon led the team to hypothesize that the use of thinner pavement sections (to induce distresses more quickly) had unintentional effects on the experiment, making the data from this experiment less useful for the development of PRS (Huber and Scherocman 1999). In 2000 an attempt was made under NCHRP Project 9-22 to advance the HMA PRS software (HMA Spec) developed in the WesTrack project. However, the capabilities of the WesTrack PRS software proved too limited for general use across the United States. An attempt to directly adapt the MEPDG software to use as an HMA PRS was then aban- doned; instead, the team used the spreadsheet solutions of the MEPDG originally developed in NCHRP Project 9-19 as specification criteria for the simple performance tests for permanent deformation and fatigue cracking. This final version of the HMA PRS was named the quality-related specification software (QRSS). The QRSS is a stand-alone program that calculates the pre- dicted performance of an HMA pavement from the volumet- ric and materials properties of the as-designed HMA and compares it with the properties of the as-built pavement cal- culated from the contractor’s lot or sublot quality control data. It computes a predicted life difference (PLD) on the basis of fatigue, rutting, and thermal cracking; and the PLD can be used to reward and/or penalize contractors for their product (Moulthrop and Witczak 2011). WarrantieS. In contrast to PCC pavements, materials and workmanship issues capable of affecting long-term asphalt pavement performance can generally be observed within a few years of construction. For this reason, asphalt pavement warranties have been more readily adopted than those devel- oped for PCC. The most benefit can be gained from using HMA performance warranties to protect the agency from early failure of the pavement (Gallivan 2011). The perfor- mance parameters typically monitored during the warranty period include the following: • Ride quality—typically measured with laser-based inertial profilers and calculated as IRI; • Rutting and permanent deformation—commonly mea- sured with laser-based or ultrasonic-based inertial profil- ers and reported as average rut depth; • Friction—typically measured with a skid trailer and reported as a friction number; and • Cracking—typically mapped using visual condition sur- veys and reported in terms of severity and extent (length or area). Longer-term DBOM contracts in the United States (e.g., 20 years to 99 years) have also been applied to asphalt pavement and other roadway features. Examples of projects involving public-private partnership, long-term warranty, or operation and maintenance agreements for HMA and other features include New Mexico DOT US-550/NM SR-44 (20 years), Flor- ida DOT I-595 P3 corridor roadway improvements (35 years), and the Capital Beltway 495 Express Lanes P3 Project (80 years). The operation and maintenance specifications provide for monitoring postconstruction performance parameters similar to those found in a warranty provision. They also address the condition of the roadway at “handback” (i.e., when responsibil- ity for the asset reverts to the agency), using parameters such as structural capacity expressed in terms of a modulus value, deflection, or residual life [e.g., in years or remaining equivalent single axle loads (ESAL)].

27 Guide Specifications A set of guide performance specifications for asphalt pave- ment was prepared under the R07 research project. Each spec- ification was drafted with a specific delivery approach in mind. The recommended performance parameters and materials and construction requirements included in each specification are therefore tied to the roles and responsibilities and the risk allocation deemed appropriate for a DBB, DB, warranty, or DBOM project. To promote rapid renewal, the guide specifications attempt to • Incorporate quality management and acceptance criteria that more closely correlate to performance (mechanistic structural and mix design properties); • Promote use of NDT techniques, such as ground-penetrating radar, which provide continuous in situ measurements and reduce the need for taking core samples; • Encourage contractors to use tools such as compaction roll- ers enabled with a global positioning system (GPS) device to ensure adequate roller pass coverage and improve uni- formity; and • Incorporate financial incentives and disincentives that promote enhanced quality. One of the biggest challenges to implementing perfor- mance specifications, particularly under the DBB and DB sce- narios, relates to the use of end-result properties that act more as surrogates than as direct indicators of future performance. Ideally, as more agencies move toward using mechanistic- empirical design procedures, measurement strategies may evolve to incorporate parameters that better correlate field data to design assumptions. However, even as testing methods and predictive models mature, certain materials and work- manship issues that cannot be measured or modeled effec- tively may still affect pavement performance. For this reason, warranties and long-term DBOM contracts will likely remain viable options for certain projects. The guide specifications provide a comprehensive example of the possible performance requirements that could be used to promote the construction of long-lasting pavements. From this menu of requirements, users should select those that best fit the needs of their particular project or program, bearing in mind that certain barriers or gaps may preclude the immedi- ate implementation of all of the proposed parameters and test methods. For example, a performance measure may be technically valid but difficult to implement. Obstacles may include a need for specialized equipment or expertise, a lack of standardized test methods, absence of historical data for calibration of design or predictive models, and so on. Each agency will have to identify and address possible gaps (particularly those related to historical data and specialized training) on the basis of their own unique experience and needs. However, current technology and business practices generally point to three tiers of performance specifications for asphalt pavement; they range from minimal departure from current practice to a substantial shift in practice and organiza- tional culture that will require technological advancement, improved understanding of long-term material behavior, and possibly a new business model. • Tier 1 requirements do not require a substantial departure from current practice, yet they place more emphasis on properties known to affect the performance of asphalt pave- ments, including volumetric properties such as air voids, asphalt content, and VMA, and as-constructed properties such as in-place density, joint compaction, and thickness. • Tier 2 requirements encourage agencies to use for accep- tance purposes more rapid and continuous nondestructive evaluation methods, such as ground penetrating radar, which, although currently available, would require capital investment and/or further advancement to incorporate into a specification. As an option under Tier 2 (specifically, Tier 2B), agen- cies may wish to prequalify or screen the contractor’s mix design using mechanistic, performance-based properties such as dynamic modulus, rutting resistance, and fatigue performance. • Tier 3 requirements assume improved understanding of long-term material behavior as well as advances in tech- nology, particularly in the area of NDT technology, which may allow for the inclusion of acceptance parameters, such as stiffness, which better reflect the future performance and design life of the pavement. Figure 3.2 summarizes these different tiers and the motiva- tions for implementing each. Although the figure suggests a time frame for implementation, to some extent, this will be agency-specific. For example, warranty provisions and long- term DBOM agreements may fall into the Tier 2 and Tier 3 categories, respectively, for agencies that would first have to foster the necessary internal and external support for assign- ing such postconstruction requirements to industry. Several agencies, however, have already implemented such specifica- tions and can provide a roadmap for agencies interested in pursuing a similar program. In general, the three tiers represent a progression toward parameters and test methods that are more indicative of in- place pavement performance. Tables 3.4 through 3.6 summa- rize the suggested performance specification strategy for each of these tiers. To help determine the appropriate tier, users should consider what would best fit the needs of their particular project or program. For example, if the goal is simply to reduce con- struction oversight, a short-term warranty may be a better option than investing in new mechanistic or NDT equipment.

28 Figure 3.2. Implementation tiers for HMA pavement. Table 3.4. HMA Pavement, Tier 1 Summary Motivation Contractor Quality Management Acceptance Implementation Issues Differences from Current Practice Tier 1 Existing Specifications and Practices • For rapid renewal, improve durability. • Reduce likelihood of poor performance. Quality Control • Asphalt content • Air voids • VMA • Compaction • Smoothness • Thickness • Moisture damage • Mix temperature • Gradation Workmanship Process Control • Temperature bar • GPS-enabled roller pattern mapping (coverage) Construction Acceptance • Asphalt content • Air voids • VMA • Compaction • Joint compaction • Surface defects • Smoothness (IRI or straightedge) • Thickness • Payment by the square yard will change the business model (e.g., lump sum versus unit- priced contracts). • Additional funds for testing will be needed. • Existing DOT man- power and skill level is acceptable. • Additional contractor equipment will be needed. • Eliminate gradation as an acceptance parameter. • Measure VMA, thickness, and joint compaction for acceptance purposes. • If measuring thickness, consider paying by the square yard. • Encourage contractors to improve process control by using a temperature bar and GPS-enabled rollers. Note: VMA = voids in mineral aggregate; GPS = global positioning system; IRI = international roughness index.

29 Table 3.5. HMA Pavement, Tier 2 Summary Motivation Contractor Quality Management Acceptance Implementation Issues Differences from Current Practice Tier 2A NDE of Tier 1 Properties • Implement rapid, continuous sampling and testing. • Improve perfor- mance (reduce risk of errors). • Reduce oversight (coring/testing). Quality Control • Asphalt content • Air voids • VMA • Compaction • Smoothness • Thickness • Moisture damage • Mix temperature • Gradation Workmanship Process Control • GPS-enabled roller pattern mapping (coverage) Construction Acceptance • Asphalt content • Air voids • VMA • Compaction (GPR correlated to cores) • Joint compaction (GPR correlated to cores) • Surface defects • Smoothness (IRI) • Thickness (GPR) • Additional agency funds for testing will be needed. • Training and more advanced skills will be required (to interpret GPR results). • Testing methods need to be monitored to ensure accuracy of results. • Measure the same properties but use different measure- ment techniques. • Sample continuously. • Reduce destructive testing (i.e., cores). Tier 2B Mechanistic Mix Design • Improve under- standing of perfor- mance (measuring design input values). • Build database of mechanistic proper- ties for inclusion in, or refinement of, MEPDG. Performance-Based Mix Design • E* (dynamic modulus) • Rutting resistance • Fatigue (beam fatigue or S-VECD) Quality Control • Asphalt content • Air voids • VMA • Compaction • Smoothness • Thickness • Moisture damage • Mix temperature • Gradation • GPS-enabled roller pattern mapping (coverage) Construction Acceptance • Asphalt content • Air voids • VMA • Compaction (GPR correlated to cores) • Joint compaction (GPR correlated to cores) • Surface defects • Smoothness (IRI) • Thickness (GPR) • Use predictive models for collecting data on mech- anistic properties; until predictive models become standard prac- tice, traditional parame- ters for payment adjustment should be used. • Postconstruction moni- toring will be needed to validate expected performance. • Additional agency funds for testing will be needed. • Training and more advanced skills will be required. • Prequalify the mix on the basis of mecha- nistic properties. • Measure design- based properties. • Use advanced test- ing methods and devices. • Reduce destructive testing. Tier 2C Short-Term Warranty • Reduce oversight during construction. • Open up require- ments affecting short-term design life or materials close to the surface. Quality Control • Asphalt content • Air voids • VMA • Compaction • Smoothness • Thickness • Moisture damage • Mix temperature • Gradation Construction Acceptance • Compaction (cores or GPR) • Joint compaction (cores or GPR) • Thickness Postconstruction Acceptance • Ride quality (IRI) • Rutting • Cracking • Surface defects • Skid resistance • Potential institutional, legal, and organizational barriers will need to be overcome. • Additional agency moni- toring and testing post- construction will be necessary. • Training will be needed because of changes in roles and responsibilities. • Reasonable thresholds based on duration of pavement warranty and maintenance agreements will have to be set. • Reduce agency oversight and testing during construction. • Make no payment adjustments at the end of construction. • Perform post- construction monitoring. Note: NDE = nondestructive evaluation; VMA = voids in mineral aggregate; GPS = global positioning system; GPR = ground-penetrating radar; IRI = international roughness index.

30 Table 3.6. HMA Pavement, Tier 3 Summary Motivation Contractor Quality Management Acceptance Implementation Issues Differences from Current Practice Tier 3A Performance Warranty or DBOM • Reduce oversight dur- ing construction. • Open up design and material requirements affecting design life. Quality Control • Submit QMP Construction Acceptance • Conformance with design, QMP, and performance requirements Postconstruction Acceptance • Ride quality (IRI) • Rutting • Cracking • Surface defects • Skid resistance • Structural integrity • Other measures defined by contractor • Only P3s or long-term con- cession agreements will work. • Potential institutional, legal, and organizational barriers will have to be overcome. • Agencies will have to administer the payment adjustment system and audit contractors’ self- reporting of postconstruc- tion performance results. • Training will be needed because of changes in roles and responsibilities. • Reasonable thresholds based on duration of pave- ment warranty and mainte- nance agreements will have to be set. • Adaptation to changes in technology (testing, materi- als, etc.) over time will be necessary. • Shift complete per- formance risk to the contractor. • Monitor actual per- formance over time. • Emphasize post- construction perfor- mance monitoring, with less oversight during construction. Tier 3B Predictive Models • Predict the perfor- mance of the as- constructed pavement to establish a basis for rational acceptance and payment decisions. • Obtain a better under- standing of the expected behavior and life of the as- constructed pavement to help plan for future maintenance needs. Performance- Based Mix Design • E* (dynamic modulus) • Rutting resistance • Fatigue (beam fatigue or S-VECD) Quality Control • Asphalt content • Air voids • VMA • Compaction • Smoothness • Thickness • Moisture damage • Mix temperature • Gradation • GPS-enabled roller pattern mapping (coverage) Construction Acceptance • Compaction • Joint compaction • Smoothness • Thickness • Stiffness • Rutting • Fatigue • DOTs and industry will have to accept predictive models. • Additional funds for testing will be needed. • Training and more advanced skills will be required. • Measure design- based properties. • Base payment on predictive models. • Use advanced test- ing methods and devices. Note: DBOM = design-build-operate-maintain; QMP = quality monitoring plan; IRI = international roughness index; P3 = public-private partnership; VMA = voids in mineral aggregate; GPS = global positioning system. Demonstration Project For longer-term contracts involving integrated services, a per- formance specification for the entire pavement system (i.e., pavement plus foundation) could be developed. Recent per- formance specifications developed in the United Kingdom and Texas for DBOM contracts have attempted to consider the entire pavement system—most importantly the foundation conditions including subbase and base or existing pavements— as part of the solution. Intelligent compaction (IC) technology may ultimately provide a means to develop a comprehensive specification for the entire subgrade/pavement system. To explore this possi- bility, the team worked with the Louisiana Transportation Research Center (LTRC) during the first quarter of 2010 to identify a suitable Louisiana Department of Transportation and Development (Louisiana DOTD) project on which to demonstrate the use of IC technology on an entire pavement section (subgrade, stabilized subgrade, base course, and HMA

31 layers). The selected project, US-90 frontage roads (between Darnall Road and LA-85), involves the construction of new frontage roads along each side of U.S. Hwy 90 in Iberia Parish. The project objectives include the following: • Demonstrate the value of real-time quality control of compaction operations to accelerate construction, reduce rework, and improve uniformity; • Improve value of field data and reduce frequency of tradi- tional sampling through improved construction process control; • Evaluate the reliability and potential use of IC data for accep- tance and measurements of in situ stiffness of the constructed earth materials; link to properties that relate more directly to design (e.g., modulus) and in-service performance; • Establish the value of using IC and mechanistic-based point measurement technologies for rapid renewal proj- ects by benchmarking against sections built using standard construction techniques; and • Establish long-term monitoring sections and monitoring protocols and assessments for LTRC to document the value of implementing this specification approach and technologies. Bridges State of the Practice in Performance Specifications Bridges pose a unique challenge for developing performance specifications. Unlike other components of highway infra- structure, bridges may last several decades because of advances in materials and structural design. At the same time, long- term degradation processes such as corrosion, scour, and set- tlement make it difficult to predict performance over a bridge’s design or service life. As a result, mechanisms such as warran- ties and predictive models that may be effectively applied to pavements are not as amenable to bridge projects. Published research related to developing performance spec- ifications for bridges primarily addresses specific material requirements and, to a lesser extent, design requirements rather than overall bridge performance. The most common areas of research to genuinely target performance criteria are working toward hybrid specifications for structural concrete and bridge decks that couple more performance-oriented parameters with the prescriptive details needed to ensure the agency’s goals will be met. As with end-result specifications for pavements, the litera- ture related to structural and deck concrete primarily focuses on identifying quality characteristics, such as strength, stiff- ness, permeability (rapid chloride penetration and conductiv- ity), and air content—all of which can provide some indication of future performance (Tikalsky et al. 2004; Haldar et al. 2004; Olek et al. 2002; Hughes and Ozyildirim 2005; Obla and Lobo 2005; ORTA 1987; Sprinkel 2004; Wenzel 2000). Several of these studies devote considerable effort to optimizing mix design toward improved material performance. A review of current bridge specifications, however, indi- cates a general lag in applying this research at the project level. Specifications have remained relatively prescriptive, requir- ing that concrete be batched, mixed, placed, and cured in accordance with the plans and specifications. The quantity and location of reinforcement is also specified. Attempts to incorporate higher-level performance parameters are more commonly seen under longer-term contracts involving inte- grated services (design, construction, operation, mainte- nance), but the underlying design requirements often still reference agency or other FHWA-approved standards. Non- conventional materials, such as fiber-reinforced polymer (FRP) composites for bridge decks and superstructures, and accelerated bridge construction techniques have generally been applied only on a pilot basis through the use of propri- etary or prescriptive specifications. Agencies have not typi- cally designed and used high-level performance specifications to motivate industry to offer such solutions in response to durability, completion time, or other renewal goals. Guide Specification Developing and implementing performance specifications for bridges presents several challenges. First and foremost, the general reluctance exhibited by safety-conscious bridge engi- neers to entrust contractors with decision-making responsi- bility provides few opportunities for innovation and risk transfer. Second, the comparatively long service lives expected of most bridge components suggests that short-term warran- ties or maintenance agreements would not provide agencies with an effective means of mitigating the risk of inferior materials and workmanship. Similarly, the length of time that would be required to make long-term warranties meaningful in the bridge environment tends to make them impractical from a business standpoint (e.g., the contracting entity might dissolve or the initial costs would be too high). The most viable options for performance specifications therefore include hybrid specifications implemented under DBB or DB for individual elements of the bridge and higher-level perfor- mance specifications for the entire bridge structure imple- mented under long-term DBOM contracts. The contracts proposed for the Goethals Bridge Replacement Project (35- to 40-year concession), the North Carolina Mid-Currituck Bridge (50-year concession), and the Indiana East End Bridge (35-year maintenance term) are examples. The bridge community will not likely embrace a perfor- mance specification for an entire bridge structure until it has seen the successful implementation of hybrid specifications for major bridge elements. Such hybrid specifications could begin to incorporate more performance-oriented parameters

32 into otherwise prescriptive specifications. Given the current state of practice, the team felt that preparing a hybrid specifi- cation for a hydraulic cement concrete deck would provide the best opportunity to begin building the support needed to transition toward a higher-level performance specification addressing the entire bridge (see Figure 3.3). A comprehen- sive bridge deck specification could then be tailored to other bridge elements, such as piers and abutments, by removing extraneous requirements. As further summarized in Table 3.7, to advance the state of practice, the guide bridge deck specification includes the fol- lowing recommendations: • Emphasize end-result parameters that relate to the dura- bility of the in-place concrete (such as permeability, rebar cover, and cracking), instead of the traditional measures of compressive strength and thickness. • Incorporate pay factor adjustments to reward the contrac- tor for providing superior product and penalize the con- tractor for providing product that is of lesser quality than specified. (Pay adjustments should be determined using a PWL approach to encourage contractors to produce con- sistent quality work.) • Address surface characteristics, such as ride quality and possibly skid resistance. The parameters and test methods included in the guide spec- ification were based on state-of-the-practice testing technology, which may or may not provide rapid and repeatable results, be representative of the anticipated field conditions, or relate directly to field performance (particularly if based on labora- tory testing). For example, although permeability is a critical durability parameter, some questions remain regarding the accuracy and repeatability of the currently available test meth- ods for evaluating this parameter (e.g., ASTM C 1202). Advance- ments in standardized test methods would eliminate some of the perceived risk in using performance specifications. Further development of nondestructive testing techniques, such as those being studied under the SHRP 2 R06A project, will also help advance rapid renewal goals. However, as these Figure 3.3. Implementation tiers for bridges.

33 Table 3.7. Summary of Bridge Performance Tiers Motivation Contractor Quality Management Acceptance Implementation Issues Differences from Current Practice Tier 1 (Concrete Bridge Deck) Existing Specifications and Practices • Place more emphasis on properties known to affect durability. Quality Control Fresh Concrete: • Density • Slump • Air content • Water content • Placement temperature • Segregation • Setting time • Evaporation rate • Thickness Hardened Concrete: • Compressive strength • Permeability • Shrinkage • Freeze-thaw resistance • Scaling resistance • Alkali-aggregate reac- tivity resistance • Abrasion resistance Construction Acceptance • Rebar location • Thickness (by probing) • Cover depth • Strength • Permeability [by chloride ion penetration resis- tance (ASTM C1202)] • Air content • Cracking (visual) • Joint condition (visual) • Cross slope • Cracking (visual) • Some additional funds for testing will be needed. • Questions remain regarding the accu- racy and repeatability of the chloride ion permeability test. • Reduce importance of strength and thickness as acceptance param- eters and instead emphasize durabil- ity of the in-place concrete by mea- suring parameters such as rebar cover, permeability, and cracking. • Incorporate pay factor adjustments for key acceptance parameters. Tier 2 (Concrete Bridge Deck) Performance- Oriented Testing • Place more emphasis on functional properties. Quality Control Fresh Concrete: • Density • Slump • Air content • Water content • Placement temperature • Segregation • Setting time • Evaporation rate • Thickness Hardened Concrete: • Compressive strength • Permeability • Shrinkage • Freeze–thaw resistance • Scaling resistance • Alkali–aggregate reac- tivity resistance • Abrasion resistance Construction Acceptance • Rebar location • Thickness (by probing) • Cover depth • Strength • Permeability (by resistiv- ity meter) • Air content • Cracking (visual) • Joint condition (visual) • Cross slope • Cracking (visual) • Skid resistance • Ride quality • Some additional funds for testing will be needed. • Historical data will be needed to identify appropriate thresh- olds for ride quality and skid resistance. • Measure functional surface character- istics such as smoothness and skid resistance. • Incorporate use of nondestructive evaluation techniques. Tier 3 (Entire Bridge) DBOM • Open up design and material requirements affecting design life. Quality Control • Submit QMP Construction Acceptance • Conformance with design, QMP, and per- formance requirements Postconstruction Acceptance • Loading • Condition rating • Geometry • Deflection/vibration • Settlement • Ride quality • Noise • Other measures defined by contractor • Instrumentation tech- niques, NDT technol- ogies, monitoring, and 3D modeling will need to be integrated to support bridge condi- tion assessment. • Data management systems, particularly for health monitoring, will be needed. • Adaptation to changes in technol- ogy (testing, materi- als, etc.) over time will be necessary. • Shift complete per- formance risk to the contractor. • Monitor actual per- formance over time. • Emphasize post- construction performance monitoring. Note: QMP = quality management plan; NDT = nondestructive testing.

34 technologies (e.g., impact echo, ground-penetrating radar) are primarily suited for evaluating problems with deterio- rated structures, they will be more applicable to specifications and delivery methods that include postconstruction respon- sibilities than to the DBB or DB case in which acceptance is based on end-of-construction measurement. A DBOM speci- fication developed for the entire bridge structure could incor- porate promising NDT devices, as well as other bridge health monitoring techniques, as possible means of conducting postconstruction performance monitoring and condition assessments in a rapid and accurate manner that minimizes traffic disruption. An ideal DBOM specification would also operate on a high enough level to encourage contractors to consider nontradi- tional materials and technologies, such as those addressed under the SHRP 2 R19A project, to achieve bridge service lives of 100 years and beyond. Given that several of the meth- ods may have higher initial costs, a postconstruction mainte- nance period or a best-value selection process that considers life-cycle costs may be required to motivate contractors to consider using such techniques. Demonstration Project The focus on durability parameters included in the guide bridge deck specification is a first step in moving the industry toward constructing longer-lasting bridge decks. To evaluate the per- formance requirement options contained in this specification, the team partnered with the Virginia DOT on a demonstra- tion project on the Route 208 bridge over Lake Anna on the Spotsylvania–Louisa County line. The performance require- ments were implemented as a shadow specification, with accep- tance and payment based on the Virginia DOT’s end-result specification for concrete bridge deck. Compared with the Virginia DOT specification, the pay fac- tors for the R07 performance specification would have resulted in a more severe penalty for certain parameters (e.g., cover depth and thickness) and a higher bonus for others (e.g., strength and air content). This finding suggests that an impor- tant consideration for implementing a specification is the need to carefully set limits for performance parameters and use pay adjustment formulas that balance targeted performance with what industry can reasonably achieve. Another important lesson learned from this demonstra- tion project is that workmanship issues can have a large effect on performance outcomes. Such issues may not necessarily be addressed or identified through the use of performance parameters measured through end-result testing. As a result, the team developed a checklist addressing inspector certifica- tion, transportation and handling, preplacement and place- ment inspection, and postplacement inspection for use as a companion document with the guide specification. Complete details regarding this demonstration project are provided in Appendix F. Geotechnical Features State of the Practice Geotechnical projects face several unique challenges in defin- ing and evaluating performance: • Geotechnical materials are among the most variable con- struction materials. Higher testing frequencies are there- fore needed to obtain statistically valid assessments of performance. • Because soil properties can change over time (e.g., as a result of postconstruction saturation), predicting long- term performance is problematic. • The subsurface aspect of geotechnical projects makes post- construction maintenance and repairs difficult, if not impos- sible. This emphasizes the need to construct geotechnical infrastructure systems properly up front with defined levels of risk. • Warranty provisions are difficult to implement because little historical data is available to establish targets and thresholds. Furthermore, extensive exclusions may be required (e.g., to address changes in groundwater conditions or vegetation over the life of the system). Given these obstacles, geotechnical specifications have tra- ditionally been prescriptive in nature. Although the literature contains several papers and reports describing performance measurements (e.g., settlement), monitoring techniques (e.g., in-ground instrumentation), and test methods (e.g., falling weight deflectometer) for evaluating geotechnical infrastruc- ture systems, only a limited number of geotechnical perfor- mance specifications exist. They are generally a hybrid of prescriptive and end-result requirements (e.g., requiring a minimum number of roller passes in addition to achieving 95% compaction). The challenge in developing a more performance-oriented specification is to move beyond the use of acceptance properties—which act only as surrogates for performance (e.g., density)—to the use of mechanistic measures (e.g., stiff- ness)—which can be more directly correlated with perfor- mance and the assumptions used in the pavement design process. Including new and emerging technology, such as intel- ligent compaction (IC), in the QA process provides a means to advance the current end-result specifications for earthworks. Roller compaction monitoring technologies with GPS doc- umentation are particularly attractive for rapid renewal pur- poses. They offer 100% coverage information with real-time data visualization of compaction data, which is a significant improvement over traditional QA plans involving tests at

35 discrete point locations. Several equipment manufacturers have been developing these technologies for both earthwork and asphalt materials over the past 30+ years. By making the compaction machine a measuring device, the compaction process can potentially be managed and controlled to improve quality, reduce rework, maximize productivity, and minimize costs. With data provided in real time, a contractor could alter the process control parameters (e.g., moisture control, lift thickness, and so on) to ensure acceptance requirements are met the first time. Project schedules would thereby be reduced, and delays resulting from postprocess inspections and rework could be avoided. To date, results from research and demonstration projects have shown the application of the IC technologies for earth- work construction to be promising, although results are somewhat limited. The FHWA has been actively engaged in an IC demonstration program, working with agencies to fur- ther develop and promote IC technology. To date FHWA has conducted more than 15 demonstrations to collect data and compare density with machine operation measurement val- ues for earthwork and asphalt pavements. The FHWA has also developed a website (http://www.intelligentcompaction .com) dedicated to IC that includes information on the tech- nology, benefits, implementation guidance, software for compiling and analyzing geospatial data, and draft IC speci- fications based on density control. FHWA plans to continue with demonstration projects, collect additional performance data, and further develop IC specifications. In addition to the FHWA demonstration program, a few pilot specifications have been and are being developed by state agencies in the United States (e.g., Minnesota DOT), and a few specifications from European countries exist. Additional work is needed in the United States before IC machine values can be implemented for acceptance purposes. Clearly, differences in IC equipment and machine measurement values, materials, GPS systems, data management, quality control (QC), and verification methods need to be resolved or standardized before IC technology and specifications can be more widely implemented. The earthwork performance specification included in Appendix C addresses the obstacle of differences in IC equipment manufacturer machine measurement values; the specification was field tested on a demonstration project in cooperation with Missouri DOT. Details of the demonstra- tion project are summarized later in this section, and the full project report is available through the R07 report web page (http://www.trb.org/main/blurbs/169107.aspx). Beyond compaction technologies, other recent develop- ments in the geotechnical field warrant consideration of performance-oriented specifications, including shallow and deep ground improvement technologies. In the past, only a handful of basic technologies were used, but now many options exist. In the field of vertical support elements, upwards of eight or more possible systems could now provide suitable solutions for soft ground improvement. Unfortunately, imple- mentation of many of the new technologies has been slow because of their proprietary nature. Implementation of performance-oriented specifications that focus on achieving overall settlement control or bearing capacity requirements would reduce barriers associated with proprietary technolo- gies and increase competition, a circumstance which should result in best-value solutions. Shallow ground improvements for pavement rehabilita- tion applications are another area in which performance- oriented specifications should improve competition and allow use of propriety technologies. Several states (e.g., Mis- souri, Pennsylvania, and Ohio) are developing specifications for pavement foundation rehabilitation. Guide Specifications Challenges with long-term monitoring and the general absence of performance prediction models generally preclude the application of PRS and warranty provisions to geotechnical projects. The guide specifications are therefore primarily end- result specifications, suitable for use under any delivery method. The end-result criteria, however, are directly linked to performance characteristics when possible. In some cases, lim- itations on the agency’s ability to directly measure key engi- neering parameter values limits the applicability of performance specifications for geotechnical applications. Ideally, advance- ments in measurement technologies will reduce this obstacle. Earthwork/PavEmEnt Foundation SyStEmS. Recent develop- ments and improvements to in situ testing devices and inte- grated machine sensors (e.g., intelligent compaction rollers with accelerometer-based measurements of ground stiffness) have provided opportunities to develop more performance- oriented specifications in the areas of embankment and pave- ment subgrade/subbase construction. Two guide specifications related to pavement foundation systems were prepared under this research effort. The first, and perhaps easiest to implement, entails substituting traditional forms of proof rolling with roller-integrated compaction mon- itoring (RICM) proof mapping to verify that pavement sub- grade support conditions are satisfactory. Compared with traditional proof rolling, proof mapping can provide the following: • Geospatially referenced documentation of a RICM mea- surement value (MV); • Real-time information to the contractor during the con- struction process; and • Results that can be correlated to subgrade support values such as bearing capacity and stiffness.

36 The second guide specification represents a more compre- hensive attempt to specify the construction of embankment and pavement foundation materials in terms of performance measures and quality statements. This specification includes the following key features: • Use of RICM technology to provide 100% sampling cover- age to identify areas needing further work; • Acceptance and verification testing using performance measures and parameters, such as elastic modulus test- ing, shear strength, and permeability, that relate to design assumptions; • Protocols for establishing target values for acceptance; • Quality statements and assessment methods that require achievement of at least some overall minimal value during construction, and achievement of a minimum level of spa- tial uniformity in a given lot area; and • Protocols for data analysis and reporting such that the con- struction process is field controlled in an efficient manner to ensure the final product meets design assumptions. The specification contains two different implementation options. 1. RICM-MV maps to target locations for QA performance point measurements. This option uses RICM-MV georef- erenced maps to identify “weak” areas on which to focus QA point measurements. Proper QC measures (e.g., con- trolling moisture content, lift thickness, and so on) should be followed during compaction. The contractor should provide the IC-MV map to the field inspector for selection of QA test locations. Judgment is involved in selecting the number of tests and test locations. Acceptance is based on achievement of target QA point measurement values in roller identified “weak” areas. If in situ QA test criteria are not met, additional compaction passes should be per- formed, or QC operations should be adjusted (e.g., mois- ture, lift thickness, etc.) and retested for QA. 2. Calibration of IC-MVs to QA performance point mea- surements. This option requires calibration of RICM-MVs to QA point measurements from a representative calibra- tion test strip before production QA testing is performed. The measurement value–target value (MV-TV) is estab- lished from project QA criteria through regression analysis and application of prediction intervals. For modulus/ strength measurements, simple linear regression analysis is generally suitable; for correlation to dry unit weight or rela- tive compaction measurements, multiple regression analy- ses including moisture content as a variable may be needed. If underlying layer support conditions are heterogeneous, relationships are likely improved by the performance of multiple regression analyses with RICM-MV or point measurement data from underlying layers. Acceptance of the production area is based on achievement of MV-TV at the selected prediction interval (80% is suggested) and achievement of target QA point measurement values in the areas with MVs less than MV-TV. Ground improvement technoloGieS. Several existing and emerging geotechnical technologies have the potential to pro- mote the goals of rapid renewal; they are often overlooked because they entail the use of proprietary systems or lack a standardized analysis and design procedure. The SHRP 2 R02 project, Geotechnical Solutions for Soil Improvement, Rapid Embankment Construction, and Stabilization of the Pavement Working Platform, addresses several of these technologies. The R02 project developed a selection tool to help users identify appropriate technologies for a given set of project conditions. To help promote the use of some of these technologies, guide performance specifications have been developed for the following application areas: • Vertical support elements (technological solutions could include aggregate columns, micropiles, jet grouting, etc.); and • Subsurface improvements for existing pavements (techno- logical solutions could include injection of expanding foam, pressure grounding with cementitious materials, etc.). By incorporating high-level performance requirements (e.g., settlement, bearing capacity, pavement smoothness, and so on), the specifications allow agencies to consider pro- posals for several competing technologies at once. In that way they avoid the possibility of creating a proprietary specifica- tion and allow contractors to select the technology that will best serve the project’s needs. Demonstration Project As part of the development of the geotechnical performance specification for earthworks, a field project was conducted in partnership with Missouri DOT in 2010 and 2011 on the Route 141 project in Chesterfield, Missouri. The project involved working with the Missouri DOT, the contractor (Fred Weber, Inc.), and an equipment provider (Caterpillar Inc.) to demonstrate earthwork QC/QA performance mea- surement technologies, including roller-integrated compac- tion monitoring (RICM) technology in combination with mechanistic-related QA testing methods (plate load tests, dynamic cone penetration tests, and borehole shear tests). Specific goals of the pilot project were as follows: • Identify suitable QA/QC testing technologies to improve test frequency and construction process control;

37 • Develop effective reporting, analysis, and evaluation protocols; • Link the design approach with construction monitoring and the proposed statistical analysis framework, and develop performance models that include a long-term performance aspect; • Study the effect of the contract delivery mechanism on the responsibilities and actions of parties involved; • Assess the cost and benefit of implementing the perfor- mance specification; and • Improve the proposed earthwork and proof mapping per- formance specifications. The results of the field-testing phase of the project were used to evaluate the proposed earthwork performance and proof mapping specifications. One of the important attributes of the proposed specifications was the use of mechanistic-based per- formance measurements and the geospatially referenced RICM data. This approach eliminates traditional moisture/density testing with a nuclear gauge and requires the contractor to field control the operation around performance design values. According to William Stone of the Missouri DOT’s (MoDOT) Organizational Performance Administration, MoDOT is looking for a technology that both MoDOT and the construction industry can utilize during QC/QA that can provide information with more uniform coverage of compac- tion data than traditional methods with an outcome being the elimination of nuclear density testing. Intelligent compaction appears to fit that role of providing number of passes and stiff- ness of material over the entire project area rather than a few point locations and will give information that is more closely linked with current design methods with mechanistic proper- ties of the aggregate, soil and pavement. (W. Stone, personal communication, 2011). RICM technology provided 100% coverage of the project. That is a major advancement over traditional testing, which tests less than 1% of the project area. Some important findings from the research work on the Missouri DOT project include the following: • Traditional nuclear density testing results are not necessar- ily repeatable between the QC and QA agents. Further, the RICM MVs are not well correlated to the percentage of relative compaction or moisture content. • Alternative in situ testing methods—including plate load testing, light weight deflectometer testing, and dynamic cone penetration testing—provide quality measurements of support conditions. • Final acceptable procedures based on proof rolling with a loaded dump truck can be replaced with RICM proof mapping. Using RICM eliminates the need to use loaded trucks, provides integrated measurements, and is faster with greater coverage. • Obstacles to implementation of RICM and alternative test- ing methods remain because of lack of training and accepted specifications. Exit interviews from the project provided positive input in favor of the technologies and general performance parame- ters used. According to Dave Dwiggins (815 operator for contractor Fred Weber, Inc.): I like the technology. It helps me know where to focus where more compaction work is needed as well as knowing when it is good. Also, it could speed up operations by not having to guess on what is going to pass. Ross Adams (roadway superintendent for Fred Weber, Inc.) stated: I like the concept if the results correlate with the acceptance criteria and it could eliminate nuclear tests on the contractor QC plan. Nancy Leroney (project inspector for Missouri DOT) noted: It could save time and money by knowing when the soil passes. I would love to eliminate the nuclear testing. Lashonda Neal (QC inspector for ABNA Engineering) stated: Great learning experience with the new technology and approaches. I liked being part of the whole experience. It could save time. With the nuclear test you actually test a very small area versus the larger area with the new tests being demonstrated. Work Zone Traffic Control Current Status Transportation agency officials and contractors express grow- ing concern that traditional owner-developed, method-based specifications for work zone traffic control (WZTC) do not provide an efficient and cost-effective means of managing the work zone. Nonetheless, the majority of related specifications in use today are generally prescriptive, dictating to the con- tractor a set of clear, specific steps for work zone management. This system provides the contractor minimal latitude and no motivation to implement innovative and potentially more efficient traffic control measures. Some agencies have begun to include performance specifi- cations for WZTC, particularly on DB projects; but many of

38 these are “performance” in title only. Although such specifica- tions identify some performance goals (e.g., “provide a safe travel corridor”), they generally do not tie objectives to a quantitative measurement strategy (e.g., “limit work zone crashes to two per month”). One example of a mature set of WZTC performance criteria was prepared by Michigan DOT under the Highways for LIFE initiative (Michigan DOT 2007). Michigan DOT incorporated clear methods of measurement and explicit contractor incen- tives and disincentives for WZTC into a special provision pre- pared for a Highways for LIFE demonstration project. Many state agencies have been more successful in imple- menting innovative contracting techniques than strict performance-based traffic control specifications as a means to accelerate construction duration and minimize traffic dis- ruption. These techniques include A+B bidding (cost plus time bidding), lane rental, active management payment mechanism, and lump-sum traffic control. Guide Specification To draft the guide work zone specification, the team gathered available work zone performance specifications developed by various states, including Maryland, Utah, and Oregon, as exam- ples. The resulting guide specification presents a menu of pos- sible performance requirements that an agency can customize to fit a particular project’s goals, jurisdiction, locale, and envi- ronment. The performance parameters within the specification focus on minimizing delay (travel time, queue length, traffic volume), minimizing construction duration, maintaining access/mobility, and maximizing public safety. Within the goals of rapid renewal, the specification is intended to help promote high-speed construction by allowing the contractor to develop a traffic management plan and construction sequence that will be most beneficial to its operations and resources, while also allowing for minimal disruption by setting performance goals around minimizing disruption to the public. Potential gaps may limit the possibility of immediately implementing all portions of the specification. For example, the use of a trip time reliability parameter appears promising but may be difficult to implement in the near term without having the necessary network infrastructure in place. Tech- nology, though continuing to improve, may not yet be ready to provide reliable data on a consistent basis. Reliability is essential if an agency wants to tie payment to the data. New technologies that use detector and video cameras to count vehicles are evolving and may address this issue. Demonstration Project In attempting to demonstrate a WZTC specification, the team engaged in discussions with Arizona DOT, Utah DOT, and South Carolina DOT. Even though no demonstration was conducted, as a result of these discussions, the team gained valuable insight into the challenges related to implementing a performance-based WZTC specification. aGency concernS. In general, the discussions revealed some agency reluctance to implement a WZTC performance specifi- cation. Agency concerns with implementing a WZTC perfor- mance specification varied but can be summarized as follows: • Concerns that the construction project would cost more because of the use of incentive payments or contractors placing a high premium on WZTC during the bidding process; • Reluctance to relinquish control over traffic control opera- tions because of the potential negative effects on traffic and undesirable publicity that would go along; • Lack of awareness of the benefits of a WZTC performance specification and how it could provide a better product; • Concerns about the risk associated with a performance specification and concerns that a quality construction project might be jeopardized; • The effort required by the agency to verify performance results of the contractor versus the potential risk if the agency relied solely on the contractor’s reported data; • Concerns related to potential safety issues during construction; • Questions about the dispute resolution process if the agency’s independent verification does not match the results of the contractor’s monitoring; and • Concern that the use of the performance specification might reduce the bidding pool. challenGeS With implementinG a WZtc Specification. Given the concerns voiced by the agencies, implementing a performance-based WZTC specification presents some chal- lenges. They include the following: • Conveying the message that the project may cost more in terms of construction cost, but when considering the real cost, including both the construction cost and the user (delay) cost, the project will cost less than if done accord- ing to a traditional method-based specification; • Finding the right project on which to apply the perfor- mance specification, which is not applicable to all projects and project types; • Helping contractors understand what they are bidding on to ensure that bids are not artificially inflated; • Having realistic expectations about costs and scheduling before the project is bid; • Understanding the reliability of technology that is used to measure performance; and

39 • Defining requirements for nighttime versus daytime work if both will be permitted. importance of SelectinG the correct performance requirement for a project. A key to successfully implementing a perfor- mance specification for WZTC is selecting the appropriate per- formance requirement for the project. There is no one-size- fits-all performance parameter for WZTC. The agency needs to establish the most important performance criteria for the proj- ect and align them with the performance requirements. In addi- tion, the following recommendations should be taken into account: • Select the performance requirements carefully. Inappropri- ate requirements will likely affect the project schedule, par- ticularly if additional phases of construction are needed. • Match the performance requirement to the project type and location. The type of facility will play a role in what the performance requirement should be. • Avoid selecting conflicting performance measures. For example, use only one performance requirement to mea- sure “minimizing delay” on a project. BeSt application of the WZtc Specification. A work zone performance specification can be used on a variety of appli- cations, but certain project types lend themselves to a perfor- mance specification better than others. Specifically, the following should be considered: • Select projects that allow the contractor to be innovative in staging the project. This would be typical of a DB project delivery method. • Avoid projects that can be performed using short-term traf- fic control. The performance specification will not work as well on mill and overlay type maintenance projects which can be done using standard special provisions along with liquidated damages clauses. • More complex projects call for increased creativity and innovation and will likely yield more value in saving con- struction time and user-delay cost. • A performance specification will be a viable option on projects in which the reduced capacity of the work zone produces speed reductions or delay increases. Value of performance Specifications Literature Review Literature quantifying the value added and/or lost by imple- menting performance specifications in highway construction projects is rather limited. Nevertheless, research and practice, particularly from outside the U.S. highway industry, generally supports the perception that performance specifications can provide several advantages. The advantages include the abil- ity to introduce new technologies, decrease overall life-cycle costs, reduce inspections, and improve quality and customer satisfaction. One of the most significant perceived benefits reported in the literature is the ability of performance specifications to promote construction innovation. Performance specifica- tions allow contractors flexibility in choosing the materials, methods, and equipment that best match their resources and expertise. This flexibility not only facilitates innovation in project execution but also allows for reductions in overall project budgets and schedules leading to an enhanced com- petitive ability (Whiteley et al. 2005). Experience Outside the U.S. Highway Industry Several highway agencies in Europe and Latin America have been gradually increasing private-sector involvement in high- way construction through alternative or integrated contracts containing design, construction, maintenance, and operational responsibilities. In doing so, several of these agencies have moved away from their traditional method specifications to more performance-oriented contracts and specifications that include functional requirements intended to capitalize on the expertise of the private sector (Scott and Konrath 2007). For example, recognizing that the earlier involvement of the contractor could increase opportunities for innovation, improve risk management, improve constructability, and reduce impacts during construction, the United Kingdom’s Highways Agency created a new generation of design-build contracts that provided for earlier contractor involvement (Matthews 2001). Under these early contractor involvement (ECI) contracts, the contractor is selected, largely on the basis of qualifications, shortly after the identification of the pre- ferred route and well before any statutory planning stages that involve public hearings. After contractor selection, addi- tional design and planning is performed with input from the entire delivery team to establish a target price for the project from that point forward. Various mechanisms are incorpo- rated throughout the design and construction process for the contractor to share in savings and participate in any losses realized when actual costs are compared with the target price. This scheme is intended to encourage additional innovation and continual improvement throughout the development of the project by the design builder. In the United States, similar performance-based contract- ing (PBC) arrangements are more common in nontranspor- tation sectors of the federal government. The Office of Federal Procurement Policy (OFPP) produced an extensive report on the results and findings of a governmentwide pilot project to implement performance-based service contracting (PBSC)

40 methods on contracts for recurring services (OFPP 1998b). Even though the entities involved in the study are not involved in road construction projects, their experiences and findings do provide an indication of the value of using performance specifications. The OFPP research project started in October 1994 when executives from 27 government agencies agreed to implement PBSC and measure its effects. Four industry associations rep- resenting more than 1,000 companies endorsed the project. The research team on the PBSC study evaluated the before and after effects of adopting PBSC. They considered variables such as contract price, agency satisfaction with contractor performance, type of work performed, type of contract, com- petition, procurement lead-time, and audit workload. The report concludes that the results strongly validate PBSC and support its use as a preferred acquisition methodology. Furthermore, the resulting data showed that PBSC, when fully and properly applied, enables agencies to obtain improved per- formance at significantly reduced prices. The agencies involved reported an average 15% reduction in contract price in nomi- nal dollars and increased customer satisfaction. The report noted that some agencies reported an initially higher up-front investment; however, the resultant savings through the use of performance-based services acquisition (PBSA) quickly offset the initial up-front investment. As a result of this study, a number of the agencies involved have moved toward adopting performance-based service contracting (PBSC) as their pre- ferred approach to contracting (OFPP 1998b). One of the agencies adopting PBSA as a standard delivery approach, the Department of Defense (DoD), produced a guidebook for PBSA. The guidebook explains that by describ- ing requirements in terms of performance outcomes, agen- cies can help achieve the following objectives (DoD 2000): • Maximize performance. Allow contractors to deliver the required service by following their own best practices. Because the prime focus is on the end result, contractors can adjust their processes, as appropriate, through the life of the contract without the burden of contract modifica- tions, provided that the delivered service (outcome) remains in accordance with the contract. The use of incen- tives further motivates contractors to furnish the best per- formance they are capable of delivering. • Maximize competition and innovation. Encourage inno- vation from the supplier base by using performance requirements to maximize opportunities for competitive alternatives in lieu of government-directed solutions. Because PBSA allows for greater innovation, it has the potential to attract a broader industry base. • Shift risk. Shift much of the risk from the government to industry as contractors become responsible for achieving the objectives in the work statement through the use of their own best practices and processes. Agencies should consider this reality in determining the appropriate acqui- sition incentives. • Achieve savings. Use performance requirements, as expe- rience in both government and industry has demonstrated they result in cost savings. Experience in the U.S. Highway Industry Attempts in the U.S. highway industry to assess the value of performance specifications have focused primarily on war- ranty provisions. Some examples follow. WiSconSin. In 1996, the Wisconsin DOT developed a compre- hensive warranty specification for asphaltic concrete pave- ments. The study was performed jointly with the Wisconsin Asphalt Pavement Association and FHWA. The anticipated benefits from implementing the warranty specification included reducing the Wisconsin DOT’s project delivery costs, lowering total project construction costs, increasing the chances of contractors using innovative construction methods and materials, and maintaining or increasing construction quality. The report published by the research team (Shober et al. 1996) outlines the unique features of the warranty speci- fication, including the warranty period, bonding requirements, pavement performance characteristics, performance thresh- olds, pavement evaluation methods, required pavement reme- dial actions, and the use of a conflict-resolution team. The Wisconsin DOT published a 5-year progress report on its asphaltic pavement warranties in June 2001. The agency acknowledged that the limited amount of performance data available made assessing long-term trends difficult, but it offered a glimpse of comparative performance data by captur- ing comparative cost data between warranty and non warranty contracts over a 5-year period (Brokaw et al. 2001). Costs evaluated under standard contracts over 5 years included mix bid prices, asphalt bid prices, tack coat bid prices, quality management bid prices, state delivery costs, and state maintenance costs. Costs evaluated under 5-year warranty contracts included warranted asphalt pavement bid prices and state delivery costs. The results of the cost comparison were broken into two categories, on the basis of the year the project was let. Projects let in 2000 were broken out because of the addition of ancillary pavements to the warranty provision and the large increase in asphalt price which occurred that year. The evaluation showed that warranty projects averaged $24.34 per ton compared with $27.72 per ton for standard projects from 1995 to 1999; and warranty projects averaged $29.34 per ton compared to $31.25 per ton for standard projects let in 2000. In both cases, the warranted projects appeared to cost less overall compared with nonwarranted projects. This cost comparison concluded that even when an initial cost was up

41 to 7% greater, warranty pavements were still more cost effec- tive than standard pavements. The report also examined the comparative performance data on the warranty and nonwarranted projects over the 5-year period. The average IRI values of the warranted pave- ments over 5 years were better compared with the average state IRI values. The pavement distressed index (PDI) values were also significantly better than average state PDI values for nonwarranted pavements (Brokaw et al. 2001). The Wisconsin DOT conducted follow-up studies that com- pared the cost and performance outcomes of warranted HMA pavements with the cost and benefits of nonwarranted pave- ments. Thirty-eight warranted and 37 nonwarranted pave- ments were analyzed from around the state between 2002 and 2006, with warranties expiring between 2007 and 2011. The agency found that the total cost, pavement distress, and antici- pated rehabilitation schedule of both nonwarranted and war- ranted hot-mix asphalt pavements were approximately equal. The cost of staff time was greater for warranted projects and the ride quality was found to be better for warranted pave- ments. Wisconsin DOT recommends that both warranted and nonwarranted pavements be monitored so that any similarities between their service lives may be determined. Though Wisconsin DOT continues to support the use of warranties (it issued a solicitation in 2012 for a consultant to assist in pavement warranty program oversight), it issued a moratorium on the use of warranties in June 2012 until it can revise the current specification to address concerns from industry and FHWA. Wisconsin DOT had made revisions to the original specification in 2011 to tighten the warranty requirements, and industry representatives have expressed concerns about their ability to meet the revised specification. In addition, FHWA has requested several changes to the Wisconsin DOT specification. colorado. The Colorado DOT research branch conducted a study to evaluate the cost benefits of short-term warranties for hot-mix asphalt pavements. The Colorado DOT study compared 10 pairs of warranty and control projects to assess their relative costs and benefits as of January 1, 2007. The projects were 3-year and 5-year warranty projects constructed between 1998 and 2003. The projects’ current performance life was between 3 and 8 years. To minimize bias, the research- ers paired projects carefully on the basis of similar character- istics: preoverlay repair work, functional class, design life, and other features (Aschenbrener and Goldbaum 2007). The research team on the study reported that on the basis of 3 to 8 years of performance information, the 3-year to 5-year short-term warranty pavements had slightly less rut- ting and were slightly smoother than the control projects. However, the cost to maintain warranty pavements was much greater. The warranty projects resulted in a shift in risk and responsibility; however, up to the time the report was pub- lished, no tangible benefits were identified by the research team. The research team concluded that, on the basis of the evaluation of these pavements, the implementation of short- term warranties of HMA was not a cost-effective tool for the Colorado DOT (Aschenbrener and Goldbaum 2007). minneSota. The Minnesota DOT has been implementing warranties in highway projects since the mid-1990s. Since that time, the agency has gained valuable experience in devel- oping and implementing warranties on both DB and DBB projects. The results of Minnesota DOT’s experience with warranties are documented in the report, Innovative Con- tracting Summary, for the period between 2000 and 2005. The report was prepared and published by the Minnesota DOT Office of Construction and Innovative Contracting. Accord- ing to the report, some of the benefits in applying specifica- tions and warranties in highway construction projects include increased product quality (lower life-cycle costs), reduced agency staffing during construction, decreased owner risk from shifting responsibility to the contractor, and better opportunities for using innovative construction techniques and methods to improve quality (Minnesota DOT 2005). Minnesota DOT also identified several drawbacks and limi- tations concerning the implementation of warranties. For example, the report states that under the warranty system, bonding and insurance requirements may eliminate smaller companies from bidding. Furthermore, some paving contrac- tors are uncomfortable with warranty issues when another contractor constructs the subgrade. Minnesota DOT also voiced the concern that enforcing warranties over longer peri- ods of time may prove difficult. The report explained how Minnesota DOT had to monitor the project in greater detail during the warranty period. In addition, when implementing warranties, contract time could increase if contractors spend more time addressing minor issues that may affect the perfor- mance of the warranty item. Despite such disadvantages, Minnesota DOT appears to favor continuing this system and applying it on different projects (Minnesota DOT 2005). Survey and Workshop Findings This section summarizes the more qualitative observations and conclusions that can be drawn from workshop discussions with agency and industry representatives. Complete details on the Delphi analysis and workshop are provided in Appendix E. In general, both the literature and expert assessments support the conclusion that using performance specifications will add value to a project. However, the value added is contingent on project objectives, project characteristics (e.g., degree of flexi- bility to meet objectives), and the type of project delivery sys- tem used. Table 3.8 summarizes the associated benefits and

42 risks of using performance specifications from the perspective of both owners and industry. According to the literature and input from practitioners, performance specifications have the potential to improve quality and long-term durability. From this perspective, they better align design requirements with construction accep- tance criteria, focusing on parameters that more directly influ- ence performance and promoting an improved understanding of performance by all parties. This improved understanding of performance has further promoted the development and use of rational performance-based payment adjustment sys- tems, replacing pass–fail decisions and judgment calls. The earlier the contractor becomes involved in a project, the greater the opportunity to realize added value. The benefit (money saved) attributable to the use of performance specifi- cations is driven by the degree of design control and flexibility extended to the contractor. Value is also affected by the dura- tion of the contractor’s responsibility for performance, with savings more pronounced for larger, longer-duration projects. Performance specifications should be considered when the actual or perceived savings resulting from their use exceed their added premium. This more often occurs when the proj- ects are large and when contractors have enough time in the contract to capitalize on efficient budgeting. However, an agency may decide to use a performance spec- ification on a smaller, less complex project to minimize risk, especially when implementing the performance specification for the first time on a pilot or demonstration project. This conclusion was also supported by the team’s interactions with agencies interested in collaborating on demonstration proj- ects. The agencies felt that smaller, less complicated projects were a more appropriate platform for implementing perfor- mance specifications for the first time because the owner and contractor risks were more manageable than would be the case on a larger, high-profile project. This observation con- trasts with the workshop conclusion that larger, complex projects provide the greatest value when using performance specifications. However, when using a performance specifica- tion for the first time, agencies should factor the risks and learning curve into the decision. A final conclusion regarding the implementation of perfor- mance specifications was that agencies and the industry can better manage any changes in business practices required by the new specifications in steps or increments. For example, the Cali- fornia Department of Transportation (Caltrans) indicated that it was implementing its performance-based long-life asphalt concrete specification for its I-710 projects in stages to allow the industry to adapt to changes in roles and responsibilities. risks associated with performance Specifications The literature revealed several different risk areas related to the use of performance specifications. The team factored this information into its performance specification development framework, as described in Chapter 2 of the specification writers guide. In summary, • Risk associated with measurement technology and sam- pling. Depending on the accuracy and reliability of the extent to which the measurements reflect the real condi- tions, some agency risk, also called “buyer’s risk,” is inherent Table 3.8. Perceived Benefits and Risks of Performance Specifications Perceived Benefits Owners Industry • Increased private-sector accountability for performance • Accelerated delivery • Potential for higher construction quality, lower life-cycle costs, and increased customer satisfaction • Potential for reducing construction inspection and administrative resources • More flexibility • Ability to be more competitive • Potential for higher rate of return through innovation and incentive contracts • Opportunity to apply innovative materials and methods to improve effi- ciency and meet performance requirements at lowest life-cycle costs • Opportunity to realize competitive advantage on best-value procurements Perceived Risks Owners Industry • Difficulty in setting appropriate thresholds and incentives/ disincentives, especially at handback • Quality and safety sacrificed to meet or beat time and budget con- straints (primarily for design-build-nonwarranty projects) • Loss of control of over highway asset (DBOM) • Overly stringent requirements and thresholds • Inflation/escalation costs (for long-term maintenance agreements)

43 in any transaction based on performance specifications. A small probability always exists that the agency may be pay- ing for rejectable work. The opposite result, or the “seller’s risk,” may also be realized: the contractor may not be receiv- ing due compensation for acceptable work (Buttlar and Hausman 2000). • Risk associated with use of predictive models. Predictive models assess future performance or predict an end result on the basis of facility characteristics soon after construc- tion, using parameters such as in-place density, asphalt content, and waterproofing ability. Predictive models are viewed as a “black box,” and their long-term reliability is often untested—especially if conditions such as traffic loads are different from those assumed in the design. They often require revisions or replacement. • Risk associated with warranty exclusions. Warranty specifications present a different set of risks because actual performance is measured for certain parameters (rutting, cracking, etc.) over time during the warranty period, and the contractor is required to fix defects only for discrete items of the work directly under its control. These specifi- cations typically define exclusions related to features of the work not covered under the warranty. The agency risk is that it may be responsible for correcting failures for items not specifically covered by the warranty. • Procurement risk. If significant contractor investment or resources are needed to meet performance requirements, some contractors may be unwilling to assume the risks associated with performance specifications. The result could be reduced competition. • Risk associated with empirical modeling. Empirical models for predicting performance over the service life are ineffective because innovative products and techniques are out of the bounds of the applicability of empirical knowl- edge (van der Zwan 2003). • Risk of defining performance parameters using qualita- tive measures. Qualitative measurements (e.g., “conduct work in a manner that ensures minimal interference with traffic”) are difficult to enforce or test for. • Risk of combining performance and prescriptive requirements. Combining performance and prescriptive requirements may restrict innovation or require contrac- tors to assume responsibility for performance when they have not fully controlled the design. • Risk associated with verification. The availability, eco- nomics, and speed of measurement and verification strate- gies may not be able to support the goals of rapid renewal. • Risk of internal agency resistance to changed roles and responsibilities. The use of performance specifications shifts greater control to the contractor, changing the traditional agency roles and responsibilities. Agency staff may attempt to retain control using traditional administration practices, reducing the effectiveness of the performance specifications and causing the agency to retain the performance risk. When to Use performance Specifications Although literature addressing the selection of method versus performance specifications is limited, a number of studies report systematic processes for selecting alternative contract- ing methods. For example, FHWA’s Highways for LIFE performance-based contracting framework provides a deci- sion tree for choosing contract type but does not address lev- els of performance specifying (SAIC 2006). Anderson and Damnjanovic (2008) report that several states have systematic processes to select alternative delivery methods. Minnesota, Utah, Ohio, California, and Pennsylva- nia offer some level of guidance in selecting alternative con- tracting methods or warranty contracts. Minnesota DOT uses a document titled Innovative Contracting Guidelines, which highlights the pros and cons of different innovative contract- ing methods, including performance warranties, and provides selection guidelines. Utah DOT has a similar document that addresses the benefits and drawbacks of different contracting methods and provides selection criteria. Ohio DOT uses the Innovative Contracting Manual to select alternative contract- ing methods. Caltrans has a similar document titled Innova- tive Procurement Practices to address issues related to selecting alternative contracting methods. Caltrans also maintains a guidance document for selecting warranty projects on the basis of project scope and characteristics. Several other depart- ments of transportation (Wisconsin, Michigan, Colorado, and Ohio) use similar screening criteria for warranties. Lastly, Pennsylvania DOT has an “Innovative Bidding Toolkit,” which divides contracting methods into three categories: (1) time- based, (2) quality based, and (3) others. For each method, the toolkit provides a variety of information, including defini- tions, benefits and risks, and typical project profiles. Outside the transportation industry, the Guidebook for Performance-Based Services Acquisition (PBSA) maintained by the U.S. Department of Defense includes screening criteria for when to use performance contracts (DoD 2000). Using these selection and screening tools as a guide as well as feedback from workshop participants, the team developed a two-part decision process for determining when to use method versus performance specifications. This process is presented in Chapter 5 of the executive guide.