Brooklyn Bridge Park Transportation Study, 3/2008

SAm SChwARTz PLLC hDR-DANIEL FRANkFURT
BROOKLYN BRIDGE PARK
proposed tunnel would be difficult to maintain, expensive to keep secure, and would
not likely find support with the MTA.
For those exiting the tunnel at the Park, Furman Street would have to be modified to
allow for a sidewalk and crossing at the exit of this tunnel, as shown in Figure VIII-4.
A crosswalk and traffic signal, as well as a sidewalk on the east side of Furman Street
would have to be added to accommodate pedestrians. This plan would require NYC
DOT approval.
The largest impediment to building a tunnel connecting the Clark Street station to the
Park is the cantilever itself. Figure VIII-5 shows the piles that support the cantilever
extending through the proposed tunnel. In order to build a tunnel at this location,
approximately 20 piles would need to be cut and the BQE would have to be alternatively
supported over the 20-foot width of the tunnel. This is also made more difficult by the
close proximity of the proposed tunnel to the existing ventilation shaft.
Figure VIII-5 Tunnel Exit at Furman Street (Section View)
PILES TO BE CUT
STRUCTURAL SUPPORT TBD
FURMAN STREET
EXISTING
CANTILEVER
STRUCTURE
PROMENADE
EXISTING BUILDING
PROPOSED TUNNEL
CONNECTING TO CLARD ST.
Preliminary structural analysis indicates that there is insufficient room between the shaft
and the tunnel to provide adequate support for the cantilever, and that an alternative
means of supporting the cantilever would have to extend over the entire shaft (+/-
40 feet). This would be expensive, not easily accomplished, and NYS DOT approval
would be questionable. The option is not considered feasible until the cantilever is
reconstructed. During the proposed widening and rehabilitation of the cantilever,
provisions could be made to allow a tunnel to penetrate the bottom of the structure.
Cost
The preliminary cost estimate for this scheme is $226 million in 2010 dollars, based on
the following:
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•
•
•
•
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MONTAGUE TERRACE
BROOKLYN BRIDGE PARK TRANSPORTATION AND ACCESS STUDY
Finishes (General Area): 51,000 s.f. X $400 per unit cost = $23,664,000
Finishes (Control Area): 12,000 s.f. X $700 per unit cost = $9,744,000
Volume: 436,800 c.f. X $100 per unit cost = $50,668,800
Structural support of BQE: $116,000,000
Design and construction supervision: $25,872,000
Total: $225,948,800
The estimate does not include the cost of obtaining the right-of-way for the tunnel nor
the potential realignment of Furman Street to accommodate the sidewalk adjacent to
the subway fare control area.
Conclusion
While technically feasible, a pedestrian tunnel extending from the Clark Street 2,3
Station to Furman Street would be costly, difficult to maintain and potentially unsafe.
Because it would only be accessible to passengers on the 2,3 subway line, its usefulness
may also be limited. Additionally, it is unlikely that NYCT would agree to maintain and
provide surveillance for a tunnel extending over 1,000 feet in length, as they are currently
closing even shorter tunnels at other stations throughout the city. Technical issues that
would need to be considered include alternative supports for the BQE cantilever and
the lack of a sidewalk or crosswalk on Furman Street for pedestrians exiting the tunnel.
Solutions to these problems could be incorporated into the planned reconstruction of
the BQE cantilever structure.