MASS TRANSIT CONCRETE DEVELOPMENTS: WASHINGTON METRO

A total of $3.1 billion worth of concrete structural construction contracts are reflected in the Washington Metro infrastructure. This utilization of concrete has been done with due recognition of advances in the state-of-the-art in concrete technology and infrastructure design methodologies. This article summarizes details of the subway system, the surface structures, and the structure-architecture relationship, and highlights noteworthy developments in the use of concrete in the Washington Metro system. New techniques and procedures were developed to meet the problems of alkali-aggregate reaction in the older underground system, and so a contribution was made to the state-of-the-art. The system's single-pass lining represents a major breakthrough in the precast lining technology in the United States. This and other highlights (plain concrete usage in final, cast-in-place lining; segmental aerial structure; concrete waterproofing technology; extended use of shotcrete; structural slurry wall construction) are also discussed.