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 <strong>Park</strong>, 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 <strong>Park</strong> 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: • • • • • • 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.
Sam Schwartz PLLc © Sam Schwartz PLLc www.samschwartz.com Douglas Adams, AICP Jee Mee Kim, AICP Youngsuk Michael Kim, AICP Alfred G. Meyer Harris Schechtman Samuel I. Schwartz, PE Jawairia Sial Jolene Yeats hDr-Daniel Frankfurt www.dfpc.com Ruth Krieger, AIA Neil Porto, PE
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