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21.1 Background Pavement-type selection is one of the challenging engineer- ing decisions that highway administrators face today. They must balance issues of both short- and long-term performance with initial and long-term costs, as well as highway user impacts. The traveling public generally does not express strong feelings on the type of pavement constructed, as long as reason- able levels of service, safety, and ride quality are provided. Pavement-type selection is a management decision process where the choice of engineering factors such as materials and structural performance must be weighed against initial and life-cycle costs. There is a certain level of risk involved in the process because of the variations in both performance and costs. Further, the typical life span of a long-life pavement sys- tem may be 30 years or more. Changes in the characteristics of the vehicle traffic over the pavementâs service life can have a significant impact on performance and life-cycle costs. Because of the competitive nature of the pavement indus- try, controversies and legislative reviews of the pavement-type selection process are not uncommon. Therefore, there is a need for a balanced and transparent process for making pavement- type selections that objectively considers different pavement design strategies representing the best solution on a specific project or roadway. It is important that the reasons for reaching the decision be fully documented. The pavement type selected for a given proj- ect may be disputed at some subsequent time, but if sound rea- sons are outlined and documented, the matter becomes only a difference of opinion. Thus, the factors that control pavement- type selection should be documented, and the persons involved in the decision-making process should be identified. 1.2 Objective and Scope This Guide for Pavement-Type Selection provides a compre- hensive set of procedures that highway agencies can use to develop pavement-type selection policies and processes. Each step is described, and the factors that must be considered are identified. Because of differences in agency decision-making processes, it is expected that each agency will adopt or mod- ify these procedures to meet its specific needs. 1.3 Application The successful application of the pavement-type selec- tion process requires a multidisciplinary approach within the agency, as well as the involvement of representatives from the paving industry. The process will need to be tailored to address an agencyâs goals and any applicable state laws. Key features that must be addressed include the following: 1. Type of Projects Covered by the Procedure: The pavement- type selection procedure is detailed and requires a rigorous effort to achieve rational results. Therefore, the procedure will yield benefits that outweigh the costs of performing the process only for projects that are significant enough in scope. Each agency needs to develop a policy governing when and how the process will be applied. The following fac- tors should be considered in establishing a policy on select- ing projects for inclusion in the pavement-type selection process: ⢠Project cost. ⢠Project length. ⢠Traffic type. ⢠Traffic volume. ⢠Road system classification. ⢠Pavement quantity. ⢠Presence of bridge structures. ⢠Lane modifications or additions. ⢠Ramps. ⢠Acceleration/deceleration lanes. 2. Identification of Alternatives: Development of a process for identifying pavement alternatives currently used, assess- ing their performance, and identifying promising new alternatives. C H A P T E R 1 Introduction
33. Application of a Life-Cycle Cost Analysis (LCCA) Procedure: This includes identification of a computational model as well as the gathering of cost and performance data for each alternative to be considered. Guidance and computational procedures for performing LCCA are being improved all the time, and it is important that the agency keep abreast of these developments. 4. Evaluation of Economic and Noneconomic Factors: After the LCCA is completed, the feasible alternatives must be eval- uated to determine whether they meet the agencyâs goals. An agency must identify those factors that previously have been used in determining pavement type, as well as newly identified factors, and weigh their importance. This guide describes the types of factors to consider and the develop- ment of a screening matrix to evaluate these factors. 5. Development of Policies for Alternate Bidding: Alternate bid- ding provides a competitive method of selecting a pave- ment alternative when two or more equivalent pavement alternatives are identified for a specific project. Policies will need to be developed as to when alternative bidding is to be used, along with the processes to be followed. 6. Development of Policies for Alternative Contracting Projects: The limits and criteria to be used for allowing the bidder to select the type and design of pavements on alternative con- tracting projects, such as design-build and performance warranty projects, will need to be determined. 1.4 Organization and Use This guide is organized into seven chapters. Chapter 1 includes introductory material. Chapter 2 provides an overview of the pavement-type selec- tion process, including a flow chart outlining the entire process. This guide addresses agency-based selection for traditional design-bid-build and alternate pavement-type bidding proj- ects, as well as contractor-based selection for design-build and warranty projects. Chapter 3 outlines the steps to identify and evaluate poten- tial pavement alternatives that should be considered in the pavement-type selection process. This chapter also presents a discussion on developing strategies for each alternative to sustain the desired performance level over the pavementâs life cycle. Chapter 4 describes LCCA of pavement alternatives, includ- ing establishing an LCCA framework, estimating initial and future costs, computing life-cycle costs, and analyzing and interpreting the results. Chapter 5 provides detailed guidance on the evaluation of pavement alternatives using economic and noneconomic fac- tors. This chapter also provides guidance on the application of an alternative-preference screening matrix in selecting the pre- ferred pavement type. The application of the screening matrix is illustrated with an example presented in Appendix A. Chapter 6 presents a discussion on the use of alternate bid- ding to select between two equivalent pavement alternatives. On these projects, the agency provides the alternatives and specifies them in the bid document, and the contractor must choose one of the agency-provided alternatives. The agency develops the bid adjustment factors based on its own pavement life-cycle model. Chapter 7 outlines the processes for contractor-based pave- ment selection on design-build and warranty projects. For these projects, when the contractor is responsible for all or por- tions of the pavement design and selection processes, the proj- ect criteria generally require the contractor to follow processes similar to the one used by the agency for design-bid-build proj- ects. However, the process may be modified if the contractor provides extended warranties or assumes responsibility for operations and maintenance. Appendix A illustrates the application of an alternative- preference screening matrix for pavement-type selection. Appendixes B and C present examples to illustrate the pavement-type selection process for alternate bidding and design-build operations and maintenance projects, respec- tively. A summary of the research performed in NCHRP Project 10-75 that led to the development of this Guide for Pavement-Type Selection is presented as an attachment to this guide.
