摘要: |
The quality of transportation projects affects nearly everyone in the United States daily. This report focuses on the mechanics of how departments of transportation (DOTs) achieve quality projects. Specifically, this reports looks at quality in design-build (DB) projects. DB has been advancing rapidly in popularity and many states now have some experience using DB in their transportation projects. In traditional design-bid-build (DBB) construction, the design and construction are done under two separate contracts. In many cases, the DOT performs the design itself and then advertises for construction contractors to bid on the finished design. In DB, the design and construction are done under one contract by the same entity. As a result, the DOT has less control over the day-to-day details of design development in the DB project. An understanding of how to ensure that DB projects achieve at least the same level of quality as DBB projects is of interest to all involved in the process. Two definitions are relevant for further discussion. First, quality is the degree of excellence of a product or service, the degree to which a product or service satisfies the needs of a specific customer, or the degree to which a product or service conforms to a given requirement. Second, quality management is the system used to manage the ultimate quality of a product. Managing quality has traditionally been the responsibility of the DOT. DOTs developed the designs, specified the materials to be used, and watched over the construction for DBB projects. In DB, however, many of the quality management responsibilities have been shifted to the design-builder. This report discusses how these responsibilities were distributed and communicated in DB projects across the nation. Also identified are the trends or practices that have become common. The objective of this synthesis is to capture the various ways in which quality assurance (QA) is handled in DB projects. The synthesis identifies different approaches, models, and commonly used practices, recognizing the differences in each of the different delivery methods. The synthesis also addresses how the core principles of QA can be satisfactorily addressed in DB projects. It applies these principles from the procurement phase to both the design and construction phases and, in the cases of projects with post-construction options for operations and/or maintenance, to the operational phase to cover the entire life cycle of a DB project. |