Transbay Transit

Malcolm Drilling’s Role in the Transbay Transit Center Project

Transbay Terminal is a transportation complex in the South of the Market area of San Francisco, roughly centered on Mission Street, Howard Street, Beale Street, and 2nd Street to the west and east. Malcolm Drilling was one of the Joint Venture partners of DND Construction, which performed Cement Deep Soil Mixing (CDSM) shoring and ground improvement scopes for Balfour Beatty Infrastructure, Inc. on the Transbay Transit Center project in San Francisco, California. The Transbay Transit Center project included the construction of cut-off shoring walls using the Cement Deep Soil Mixing (CDSM) method to form the cut-off shoring walls for the train box excavation.

The project comprised 45,700 cubic yards/379,000 square feet of overlapping soil-mixed columns measuring 3 feet in diameter, with 2 feet in the center. Depths were predominantly 105 feet, although the buttress ground improvement and a portion of the shoring wall extended up to 120 feet deep. Flange beams, 95 feet and 120 feet in length, were installed in every other column. The project also included remobilizations to facilitate the shoring wall’s crossing of multiple active city streets.

Malcolm Drilling