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1 Background 1.1 Research Problem Statement The United States invests billions of dollars in road infra- structure each year, with a significant portion of these costs going to drainage components. Given the scale of investment, as well as tightening budgets, it is more critical than ever to optimize value across all areas of transportation projects. The last few decades have seen huge improvements in drainage pipe materials and products. However, these innovations have yet to be fully embraced by agencies and individual design firms, because it is difficult to keep up with the vast array of new pipe options and individual pipe systems. Designing, specifying, and bidding drainage pipe systems for highway projects are generally routine activities that occur on virtually every highway construction project. Because most pipe systems by their nature are routine, and separately are relatively low cost items, there is little incentive on individual projects to go beyond the basic task of identifying a system that works. Thus, the extensive database that exists on this topic addresses all the basic design issues, but generally fails to define a logical design practice that is (a) thorough, (b) com- prehensive, and (c) does not stop when the first viable design option is found, but instead, finds every viable option that will meet an owner-agency requirement in terms of function and performance. While in most instances the traditional âmeans and methodsâ specification approach to tender delivers a serviceable drainage system, it severely limits competition among the manufacturers and suppliers of pipe products. The process can be further impaired by a lack of understanding of drainage pipe alternatives or by misconceptions about the suitability or relative performance of different pipe systems. If transportation projects took full advantage of available drainage-system technology, value could be significantly increased. Giving contractors the ability to choose, at the bidding stage, from among alternative solutions that are of satisfactory quality and equally acceptable on the basis of engineering design criteria has been shown to promote com- petition and lower costs. 1.2 Objective of NCHRP Project 10-86 The general objective of NCHRP Project 10-86 is to develop a procedure suitable for adoption by American Asso- ciation of State Highway Transportation Officials (AASHTO) to guide owner-agencies and industry in the implementation of performance-based procurement for drainage systems on highway construction contracts. A solution lies in an approach that allows all pipe products on the market to be objectively categorized by assessing their quality, performance, and serviceability; by making this infor- mation readily available to agencies and their designers; and by creating a streamlined (and preferably automated) design and selection process that allows a rapid and reliable selec- tion of suitable pipe systems for a particular application. This approach will allow all acceptable pipe systems to be included in a roadworkâs tender on an equal footing. The NCHRP Project 10-86 research team was assigned to devise a system that is technically sound, that is versatile (i.e., can be adapted for any jurisdiction in any geographic location), and that can deliver better performing highway drainage systems on a much more cost-effective basis than the traditional approaches to drainage system design and procurement. Specific objectives of NCHRP Project 10-86 were to perform the following: â¢ Review and consider the state of the practice regarding drainage systems. â¢ Develop a Recommended Practice for pipe system eval- uation that encompasses key factors controlling pipe materials and performance (site characteristics, strength, hydraulics, durability, constructability, construction and post-construction costs, maintenance, and rehabilitation). â¢ Evaluate the Recommended Practice through trial applica- tions representing a variety of geographical and use condi- tions in cooperation with a number of state DOTs. C H A P T E R 1
2â¢ Present the Recommended Practice in AASHTO format suitable for balloting and subsequent implementation by owner agencies. The Recommended Practice for establishing and imple- menting successful alternative bidding of highway drainage systems is in the form of a framework that ensures technical soundness, completeness, and transparency in design, while maintaining the ability of agencies to use their local experience and risk tolerance in the alternative pipe system selection pro- cess. The level of risk associated with the use of new products or construction practices is mitigated through a robust assessment of the structural, hydraulic, and durability performance of each installation using local environmental parameters, experience, and state-of-the-art assessment methodologies. The Recom- mended Practice has been developed with the specific intent to allow for future refinement and development of a stan- dardized design and bidding tool, if further standardization is achieved across certain aspects of drainage pipe design. The Recommended Practice will have the following functions: â¢ Provide a systematic, rational, comprehensive, and tech- nically sound process for the evaluation of pipe systems (incorporating pipe and backfill materials and their inter- action). â¢ Aid designers and bidders in selecting appropriate and cost-effective pipe systems for specific applications and site locations. â¢ Be used by agency engineers or consulting engineers retained on behalf of agencies for conventionally procured contracts or by designers as part of design build consortia on alter- native financing and procurement contracts. â¢ Incorporate a comprehensive evaluation of site character- istics (environmental, geotechnical, hydrogeological). â¢ Evaluate hydraulics, structural performance, and durabil- ity in a streamlined and technically sound manner. â¢ Integrate use of best available practices. â¢ Use a novel matrix approach that facilitates clarity and transparency. â¢ Allow confidence in, and tracking of, post-construction performance. â¢ Be mindful of constructability, operational, and mainte- nance requirements. â¢ Have an expandable framework enabling modifications as new methods and materials are developed. â¢ Have an underlying framework that is flexible, enabling customization to address individual agency needs. â¢ Handle major design issues in an efficient manner and provides options for special design cases. 1.3 Purpose and Structure of the Report This report summarizes information from the research completed as part of NCHRP Project 10-86 as an accompa- niment to the Recommended Practice for Alternative Bidding of Highway Drainage Systems (Appendix A). While a great deal of information is presented in this report, it does not cover all aspects or interim decisions related to the project. The developed Recommended Practice for Alternative Bidding of Highway Drainage Systems in AASHTO format is provided as Appendix A. An accompanying userâs manual including worked examples (Appendix B) is available on the NCHRP Project 10-86 web page at www.trb.org.