The Metropolitan Washington Airports Authority managed the extension of Metrorail to the Dulles Airport, one of the nation’s largest airport hubs. The $2.5 billion project increased the rail miles within the Dulles Corridor Metro system by nearly 25%. Due to the density of infrastructure and utilities in the project corridor, it was recognized as one of the most challenging projects to be undertaken in the Northern Virginia area. Accurately documenting the location of all utilities and other structures and anomalies, both above and below-ground was critical to project design and planning to allow for relocation and redesign as needed to avoid disruption of service and public safety issues during construction in this highly commercial area, which includes governmental communication lines.
T2ue provided Subsurface Utility Engineering services in three phases for approximately 23 miles of the proposed track alignment. The first phase consisted of existing records research (ASCE Quality Level D), which was gathered from a wide variety of sources; the second phase was designating the horizontal position of approximately 400,000 linear feet of existing utilities (ASCE Quality Level B);and the third phase was determining the precise horizontal and vertical location of more than 800 utilities by using non-destructive vacuum excavation services, or test holes to achieve ASCE Quality Level A.