The Federal Transit Administration approved last month the Metropolitan Washington Airport Authority’s revised testing plan for eleven 30-year-old foundations that will be used to support piers for the new Dulles Metrorail extension in northern Virginia to Dulles International Airport.
The concrete foundations, supported by concrete and steel caissons driven 50 to 60 ft deep, are among 13 that were installed by the Virginia Dept. of Transportation in the mid-1970s during construction of the Metrorail Orange Line, in anticipation of a future extension through the Dulles Corridor.