Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
7C h a p t e r 1 Background Transportation agencies are under increasing pressure to improve mobility while maintaining existing facilities with limited resources. In response to this pressure, agencies have begun experimenting with ways to accelerate construction and minimize disruption to existing users while improving mobility, safety, and long-term performance. To help advance such initiatives, Congress established the second Strategic Highway Research Program (SHRP 2) in 2006 to pursue research in four focus areas: Safety, Reliability, Renewal, and Capacity. The Renewal area looks at improving the aging and increas- ingly congested infrastructure through design and construc- tion methods that accelerate construction, cause minimal disruption to road users and the community, and produce long-lasting facilities. Traditional method specifications may act as a barrier to the innovation often needed to achieve those objectives. Thus, SHRP 2 Project R07 was tasked with developing performance specifications that could motivate and empower the contracting industry to provide creative solutions to save time, minimize disruption, and enhance durability in the interest of rapid renewal. What Are Performance Specifications? As used in this document, the expression performance spec- ifications serves as an umbrella term, broadly encompassing various nontraditional specification types used or pro- posed for use in the highway construction industry. They include end-result specifications, quality assurance (QA) specifications, performance-related specifications (PRS), performance-based specifications (PBS), and warranty and long-term maintenance provisions. (For more detail on these different specification types, refer to the definitions provided in Appendix B.) In general, these specification types represent a progression toward increased use of higher-level acceptance parameters that are more indicative of how the finished product will perform over time. To varying degrees, they attempt to shift more per- formance risk to the contractor in exchange for limiting pre- scriptive requirements related to the selection of materials, techniques, and procedures. By relaxing such requirements, performance specifications have the potential to foster contrac- tor innovation and thereby improve the quality or economy, or both, of the end product. Figure 1.1 places these specification types along a continuum of increasing contractor responsibility for performance. At one end of the continuum are the traditional method specifications through which the agency retains primary responsibility for end-product performance. Moving along the continuum, per- formance specifications that allow for quality price adjustments based on end-result testing or predictive models begin to shift performance risk to the contractor. At the other end of the con- tinuum, postconstruction performance provisions are designed to monitor and hold the contractor accountable for actual per- formance over time. Rationale for Using Performance Specifications While the motivation for using performance specifications will likely vary from agency to agency and from project to project, the literature suggests that implementing perfor- mance specifications has the potential to improve quality and long-term durability, encourage innovation, accelerate con- struction, and reduce an ownerâs quality assurance burden during construction (particularly if the contractor has post- construction responsibilities). Such objectives (whether set internally by the agency or externally, as in a legislative mandate) will influence both the development and the use of performance specifications. Introduction
8Understanding the basic rationale for using performance spec- ifications is therefore an important first step toward ensuring successful implementation. Once identified, these objectives must be prioritized and then communicated, understood, and accepted by all parties involved. In addition to agency person- nel, the parties may include the public, legislators, industry, and sureties. Deciding Between Method and Performance Specifications As summarized in Tables 1.1 and 1.2, both performance and method specifications hold unique advantages and disadvan- tages. Those differences should be carefully weighed when considering how best to specify requirements for a particular project or project element. The likelihood of realizing the advantages of each speci- fication type tends to correlate with project complexity. Per- formance specifications are typically most advantageous when the nature of the project provides ample opportunity for the industry to innovate and influence performance outcomes. That is often the case on complex projects involv- ing major reconstruction or new capacity, multiphased work zone management, major or nonstandard structures, and high traffic volumes requiring accelerated design and construction. In contrast, unless the agency allows significant latitude with regard to the selection of alternative designs, materials, or construction methods, noncomplex projects (e.g., those involving minor resurfacing or restoration of the pavement surface, or the use of standard structural components to match existing facilities) tend to be less than ideal candidates for performance specifications. When more latitude is allowed, even minor resurfacing projects can benefit from the use of performance specifications. For example, a speci- fication based on mechanistic testing and models (e.g., S-VECD) can provide an indication of the expected long- term performance of a mix design, allowing the agency (or the contractor) to tweak the design to improve its expected performance. Figure 1.1. Continuum of highway specifications. Table 1.1. Advantages and Disadvantages of Performance Specifications Advantages Disadvantages ⢠Performance specifications promote contractor innovation. ⢠The contractor assumes more performance risk. ⢠Contractors have the flexibility to select materials, techniques, and procedures to improve the quality or economy, or both, of the end product. ⢠A performance specification can provide a more rational mechanism for adjusting payment based on the quality or performance of the as-constructed facility. ⢠The agency can exert less control over the work. ⢠Opportunities for smaller, local construction firms may be reduced. ⢠It can be challenging to identify all of the parameters critical to performance and establish related thresholds. ⢠Roles and responsibilities of the contractor and agency can become blurred if not adequately defined in the specifications or contract documents. ⢠Staff may be reluctant to assume new responsibilities. Source: FHWA 2010.
9research products As an outgrowth of its research efforts, the R07 team devel- oped guide specifications and associated implementation guidelines to support the application of performance specifi- cations across a wide range of work and projects. Guide Specifications To help agencies with the specification development process, the team prepared a set of guide performance specifications that specifiers may use as a template from which to develop project- specific performance requirements. These guide specifications provide comprehensive examples of performance specifications for different project elements and delivery methods (design- bid-build, design-build, warranty, design-build-operate- maintain). Given the difficulty of anticipating every rapid renewal need, the guide specifications are limited to the applica- tion areas that demonstrated either the greatest need or the potential for performance specifying: ⢠Asphalt pavement; ⢠Concrete pavement (cast-in-place and precast); ⢠Concrete bridge deck; and ⢠Work zone traffic management. As provided in Appendix C, specifications were also devel- oped to advance the use of intelligent compaction techniques for acceptance of embankment/pavement foundations. These specifications are not ready for immediate implemen- tation on a construction project because of training needs and limitations in technology, data analysis software, and endorsed test methods and standards. Nevertheless, they present an approach for establishing target values for accep- tance on the basis of engineering parameters that relate to design assumptions. Commentary has been built into the specifications to help specifiers select performance parameters and performance measurement strategies (test methods, sampling plans, tar- get values, pay adjustment mechanisms) that best align with the projectâs goals and the capabilities of the agency and local industry. The specifications emphasize the useâto the extent possibleâof new and emerging nondestructive test- ing (NDT) techniques that facilitate rapid renewal and per- formance parameters that validate mechanistic models of design. Implementation Guidelines To accompany the guide specifications, the team also pre- pared a two-volume set of implementation guidelines. Strate- gies for Implementing Performance Specifications: Guide for Executives and Project Managers provides a broad overview of the benefits and challenges associated with implementing performance specifications. Recommendations in this execu- tive guide address project selection criteria, procurement and project delivery options, industry and legal considerations, and the various cultural and organizational changes needed to support the implementation of performance specifica- tions. The guidance is geared primarily to an audience of decision makers but is intended to be accessible to all mem- bers of a project team. The second volume, Framework for Developing Perfor- mance Specifications: Guide for Specification Writers, is written to help specifiers tasked with preparing project-specific per- formance requirements. The specification writers guide pre- sents a flexible framework for assessing whether performance specifying is a viable option for a particular project or project element. If it is, this volume explains how performance spe- cifications can be developed and used to achieve project- specific goals and satisfy user needs. Specifiers may use this volume alone or in conjunction with the guide performance Table 1.2. Advantages and Disadvantages of Method Specifications Advantages Disadvantages ⢠Method specifications are well established, easily understood, and applicable to a wide range of topic areas. ⢠Agency can exert significant control over the work (however, this may come at the expense of increased agency inspection efforts). ⢠Requirements are based on materials and methods that have worked in the past, minimizing risk associated with newer or less proven methods or varying contractor performance. ⢠The contractor has little opportunity to deviate from the specifications and, provided that the specifications are met, is not responsible for performance deficiencies of the end product (i.e., the agency retains performance risk). ⢠Method specifications lack built-in incentives for contractors to provide enhanced performance (e.g., cost, time, quality, etc.). ⢠The prescribed procedures may prevent or discourage the contractor from using the most cost-effective or innovative procedures and equipment to perform the work. ⢠Contractor payment is not tied to the performance or quality of the work. ⢠Acceptance decisions based on test results of individual field samples can increase the potential for disputes. Source: FHWA 2010.
10 specifications to develop and tailor performance specifica- tions to help achieve project goals. research Scope and Objectives The specifications and implementation guidelines were designed to meet the following stated objectives of the R07 project: ⢠Reduce the completion time of renewal projects while maintaining or improving quality; ⢠Encourage further innovation by reducing manda- tory method requirements and defining end-product performance; ⢠Develop different performance specifications for highway construction (pavements, bridges, work zone, etc.) with vari- ous contracting scenarios (design-bid-build, design-build, warranties, etc.); ⢠Develop recommendations on the transition to and use of performance specifications; and ⢠Address strategies to equitably manage and minimize risk to all parties. A four-phase research effort was performed to develop products capable of meeting those objectives. Phase I Phase I entailed performing a comprehensive literature review to establish the current status of performance specifying in the highway construction industry. The primary resources included relevant reports from the Federal Highway Adminis- tration (FHWA), American Association of State Highway and Transportation Officials (AASHTO), and National Coop- erative Highway Research Program (NCHRP), as well as additional reports and specifications from departments of transportation and industry. The team also focused on con- tracts and specifications from long-term performance-based maintenance and design-build-operate-maintain contracts from Canada, Europe, and Australia. Several of these inter- national contracts represent a second- or third-generation attempt at performance specifying; thus they provided valu- able insight into how performance requirements may evolve as technology advances and the local performance contracting industry matures. Phase I also included an assessment of the various risks associated with performance specifications, such as a lack of understanding of long-term material behavior, limitations with performance prediction models, and gaps associated with measurement and testing technology. Effective allocation and management of these risks is a key component of the specification development process described in the specifica- tion writers guide. Phase II The ideas explored in Phase I were advanced further during Phase II. The team established quantitative performance measurement strategies specific to particular aspects of high- way construction (e.g., pavements, bridges, geotechnical applications, and so on) in the context of various contract delivery and risk allocation approaches. In a related task, the team prepared detailed specification outlines that formed the foundation for the specification development work per- formed during Phase III. As part of Phase II, the team also performed an assessment of the potential value of implementing performance specifi- cations to promote innovation, reduce inspection costs, enhance quality, accelerate construction, and achieve similar performance goals. The potential benefits were then consid- ered during a related task: to develop procedures for deciding whether to use performance or method specifications for a specific project or element of a project. These procedures were incorporated into the project selection process described in Chapter 5 of the executive guide. Phase III Building on the efforts of the prior phases, during Phase III the team established a step-by-step process for developing performance specifications: 1. Identify user and societal needs and goals. 2. Translate user needs and goals into functional perfor- mance parameters. 3. Consider contract delivery approach. 4. Determine the appropriate measurement strategy. 5. Structure incentive strategies and payment mechanisms. 6. Identify gaps (in parameters, measurement, testing, etc.). 7. Identify and evaluate risks related to performance requirements. 8. Draft specification language. This framework was used to develop draft performance specifications for vetting or validation during Phase IV. Phase IV During Phase IV, the draft performance specifications were reviewed and vetted through a series of joint agency and indus- try forums. Additionally, two demonstration projects were
11 conducted to evaluate the use of performance specifications for pavement foundations and bridge decks. Performance data were collected and results were compared with standard speci- fication practices. report Organization This final report documents the results of the R07 research effort. As summarized in this introductory chapter, the pri- mary focus of the project was the development of guide per- formance specifications and associated implementation guidelines. Chapter 2 addresses the methodology by which the team developed these products. Chapter 3 summarizes the current state of performance specifying in each research area, how the guide specifications attempt to advance the state of practice, and what additional developments would be necessary for the specifications to evolve further. Chapter 3 also documents the teamâs efforts to validate the performance specifications through vetting work- shops and demonstration projects. Finally, Chapter 4 presents the key findings from this research study as well as recommen- dations for advancing the use of the research products.
