Navy Yard Metro West Entrance Modifications
The Navy Yard Station West Entrance Modification project transformed the existing Green Line station and tripled its operating capacity in anticipation of the opening of nearby Nationals Park in Washington, D.C. The project’s contract was unique in that it involved three parties: Clark, the project’s design-builder, the Washington Metropolitan Area Transit Authority (WMATA), the project’s owner, and MR Ballpark 5, owner of the property where the expanded Navy Yard station would meet the street level.
The Navy Yard Metro Station’s original west entrance, one block north of Nationals Park baseball stadium, had an existing capacity of 5,000 persons per hour. The modification increased the west entrance's capacity to 15,000 persons per hour. The Metro construction was incorporated into the construction of the 55 M Street office building that is adjacent to and above the existing west entrance. The station’s mezzanine pay area was moved from inside the station to the ground level, where it was expanded into a 6,215 square-foot lobby integrated with the new office building. To transport customers from the street level to the platform, a new stairway and a hydraulic elevator were installed. A 3,330 square-foot passageway was constructed at the lower mezzanine to access a new traction elevator and exit stairway to the street level.
Connecting the street level with the below-ground Metro plaza required a 50-foot-deep excavation. A braced soldier pile and lagging shoring scheme supported the existing escalators and provided access to the tie-in point for the expansion of the mezzanine level. Gaining access into the existing tunnel involved the demolition of four-inch-thick concrete walls and slabs. The concrete tunnel then needed to be rebuilt to support nearly 40-foot of backfill while creating a new 16-foot-wide portal to access the expanded mezzanine elements located below the P-3 parking deck of the adjacent new building.
A majority of the work performed at the Navy Yard Metro Station was overlapping between work in the station, the new passageway, and the new entrance in the lobby of the office building. The team, per the client's request, completed the project with high coordination and no interruption to the office building construction or to train and pedestrian traffic in the station. Even though the west entrance was closed to the public during renovations, the station remained in service with trains and passengers directly adjacent to construction. Despite these complications, Clark completed this complex work before the Nationals’ opening game.
The single greatest innovation on this complex project was the negotiation of an unsolicited alternative approach, which incorporated the upgraded station into the envelope of the proposed office building. Clark worked closely with MR Ballpark 5 and WMATA to define the RFP documents. The resulting agreement produced tie-in requirements to the existing structure that called for minimal demolition and reconstruction of the existing facility and simultaneous construction of the station and office building, which allowed for the seamless integration of certain systems.