Brooklyn Bridge Park Transportation Study, 3/2008

SAm SChwARTz PLLC hDR-DANIEL FRANkFURT
VIEW PLANE
BROOKLYN BRIDGE PARK
Figure VII-3 Pedestrian Elevator and Tunnel behind Promenade
FURMAN STREET
PROMENADE
EXISTING
CANTILEVER
STRUCTURE
TUNNEL (+/- 140FT)
NEW ELEVATOR AND STAIRS
ON MAPPED PARKLAND (+/- 66FT)
EXISTING BUILDING
VIEW PLANE
This approach presents many obstacles. Modification of the cantilever support structure
would require NYS DOT approval. Approval from NYCT would also be required to build
a structure directly over the subway tunnels. As the tunnel is enclosed and has virtually
no visibility from the street, Park visitors would enter the Park via an underground
passageway with associated security and safety costs and concerns. As there is no
sidewalk on the east side of Furman Street, an expanded sidewalk and traffic signal
would be required to exit the tunnel and cross the street to the Park. NYC DOT would
have to be consulted to add a sidewalk or portion of a sidewalk to Furman Street. A
maintenance and operation entity for this tunnel and elevator would have to be
determined. NYC Parks owns the land that would be used for the elevator and tunnel,
but the agency does not have experience maintaining them. If a separate entity is
established to maintain Park amenities, elevator maintenance responsibilities could be
contracted.
The preliminary cost estimate for this scheme is $80 million in 2010 dollars; further cost
details are shown in Table VII-1 following Alternative 4.
MONTAGUE TERRACE
BROOKLYN BRIDGE PARK
BROOKLYN BRIDGE PARK TRANSPORTATION AND ACCESS STUDY
Alternative 2: Pedestrian Bridge and Elevator in Front of Promenade
The second scheme is a bridge from the Promenade across the BQE and Furman Street
that meets an elevator and stair tower at the edge of the Park, shown in Figure VII-4.
Figure VII-4 Pedestrian Bridge and Elevator in Front of Promenade
NEW PEDESTRIAN BRIDGE (+/- 60FT)
NEW ELEVATOR AND STAIRS
ON BBP LAND (+/- 66FT)
FURMAN STREET
EXISTING
CANTILEVER
STRUCTURE
PROMENADE
EXISTING BUILDING
Figure VII-4 depicts a simple arch bridge but a different structural system such as a cable
stayed bridge, a truss, or other type of distinctive structure would be possible. It is likely
that whatever the structure is, it would penetrate the view plane and a zoning variance
would be required. This fact alone may make this approach unfeasible. The bridge
could be composed of thin structural members that give an illusion of transparency,
and the elevator shaft and stair tower could be glass enclosed to maximize the view
through them to the vista beyond. This would also provide a new observation point
from Brooklyn Heights; at a height of 64 feet above the Park, a visitor could look out
of a glass elevator at the city skyline, creating the “world class vista” described by the
public at the community charrette. To accommodate expected pedestrian traffic, the
width of this bridge is preliminarily set at 15 feet. The design load for a pedestrian
bridge is 100 pounds per square foot due to the possibility of pedestrian overloading
during peak use times. To maintain the vertical clearance required for the BQE below,
the main members of the bridge structure would likely be located above the walking
surface of the bridge.
The vertical shaft would contain one or two elevators and a staircase. (The cost estimate
shown in Table VII-1 following Alternative 4 includes one elevator.) The elevators should
be large enough (for example, 10 feet by 10 feet) to accommodate a large volume of
Park visitors. Elevator construction requires an elevator cab approximately 8 feet high
with additional space in the shaft above the cab for the hoist mechanism and overrun
requirements, which would extend well above the Promenade.