According to the Barclays Center Official Statement, prepared by Goldman Sachs for the tax-exempt bond deal, a document called the Transit Improvement Agreement--yet unseen--gives the developer (via a subsidiary termed, in shorthand, RailCo) ten years to house the entrance in a temporary canopy before the Metropolitan Transportation Authority would build a permanent one at the developer's expense.
In other words, they have a decade to construct Building 1.
From the document:
RailCo may install a high quality fabric and steel temporary canopy over the Subway Entrance in accordance with the approved plans and specifications. If RailCo or its affiliate or its successor does not commence the construction of a permanent building that would enclose the Subway Entrance within such building within ten (10) years after Final Completion of the Subway Entrance (as defined in and determined in accordance with the Transit Improvement Agreement), RailCo and/or such successor must replace the temporary canopy with a permanent canopy meeting the Authority Standards for a free-standing subway entrance. If such temporary canopy is not replaced within such ten-year period, the Authority may construct such permanent canopy at RailCo's expense. If a temporary canopy is installed, the installation of a permanent canopy is not a condition of the achievement of Beneficial Use of the Subway Entrance, Substantial Completion or Final Completion, as each term is defined in the Transit Improvement Agreement.More about the agreement
Here's the overview of the Transit Improvement Agreement:
The Transit Authority and RailCo will enter into an agreement (the "Transit Improvement Agreement") pursuant to which RailCo will undertake the design and construction of certain work described therein and furnish and install certain equipment in accordance with the Authority Standards (as such term is defined in the Transit Improvement Agreement) and the approved plans and specifications therefor. Such work (the "Transit Improvements") consists principally of: (i) construction of a new subway station entrance (the "Subway Entrance"), at grade at the southeast corner of Atlantic Avenue and Flatbush Avenue, that will serve as the main entrance from the Arena to the Atlantic Terminal transportation complex (the "Transportation Complex"); (ii) construction of a mass transit access area (the "Access Area") located one (1) level below the street surface and containing a new fare control area (the "New Fare Control Area") adjacent to the IRT (2/3/4/5) and BMT (Brighton) (B/Q) subway lines consisting of eleven (11) turnstiles, three (3) high wheels, and two (2) gates; (iii) installation of stairs, escalators and an elevator compliant with the Americans with Disabilities Act (the "ADA") providing access to the New Fare Control Area from grade level; (iv) construction of a general purpose ramp connection from the New Fare Control Area to the existing underpass at the south end of the IRT 2/3/4/5 platform (the "Southern Underpass"); (v) restoration and reopening for public use of the Southern Underpass; (vi) construction of an ADA-compliant ramp connection from the New Fare Control Area to the Manhattan-bound IRT 2/3 platform; (vii) removal and relocation of any storage and equipment rooms that are impacted by the Transit Improvements; (viii) restoration of the stairs between the IRT 4/5 platform and the Southern Underpass; (ix) installation of new stairs between the New Fare Control Area and the Brighton B/Q subway line mezzanine and from the Brighton subway line mezzanine to the Brighton subway line platform; (x) installation of new signage throughout the Transportation Complex (including directional signs and those contemplated by the TA Naming Rights Agreement); (xi) at the Transit Authority's request, construction within the Access Area of a Transit Authority operations room to help coordinate train service and transit rider movement after Arena events; (xii) reconstruction of a closed street stair as a separate emergency stair to the sidewalk with a kiosk (if required) complying with requirements of the New York State Code Office; (xiii) relocation of existing Transit Authority vents on the east side of Flatbush Avenue between Atlantic Avenue and Fifth Avenue and repair of existing Transit Authority vent structures affected by the Transit Improvements to meet Authority Standards for load requirements (the "Vent Work"); and (xiv) fabrication and installation of an agent booth in the New Fare Control Area in accordance with Authority Standards.