feis chapter 3 final 082008v6 - nysdot home...kosciuszko bridge project iii-84 september 2008...

Final Environmental Impact Statement Section III.C

Kosciuszko Bridge Project III-82 September 2008

C.2.c. Pavement

All of the Build Alternatives would include the replacement of the existing Brooklyn Connector and Brooklyn ramp structures and the reconstruction of the at-grade Queens ramps. All of the work would include full deck replacement. The new Brooklyn Connector, Brooklyn ramp structures, and Queens ramps would consist of a new 240 mm (9-1/2”) thick reinforced concrete deck slab with integral wearing surface.

The Rehabilitation Alternatives (RA-5 and RA-6) would also include the rehabilitation of the existing Brooklyn Approach, Main Span, and Queens Approach, including the removal and replacement in kind of the 108 mm (4-1/4”) thick concrete filled steel grid deck.

All of the Build Alternatives would also include new bridge structures, either as a new parallel bridge in the Rehabilitation Alternatives, or as a new bridge replacing the existing Brooklyn Approach, Main Span, and Queens Approach for the Bridge Replacement Alternatives (BR-2, BR-3, and BR-5). The new bridge structures would likely be new concrete box girders and consist of a 40 mm (1-9/16”) wearing surface.

C.2.d. Structures

All Build Alternatives would replace the Brooklyn Connector (Bridge Identification Number [BIN] 1-07569-9), Vandervoort Avenue entrance ramp (BIN 1-07569-B), and Meeker Avenue/Morgan Avenue exit ramp (BIN 1-07569-A). All Build Alternatives would include new bridge structures, either built on one side of the existing bridge as part of the Rehabilitation Alternatives, or as a new bridge replacing the existing structure (BIN 1-07569-9), consisting of the Brooklyn Approach, Main Span and Queens Approach. A brief description of the proposed structures included as part of the Build Alternatives is presented below. Bridge plans, sections and elevations for all the Build Alternatives are shown in Appendix D.

BROOKLYN CONNECTOR

The new Brooklyn Connector (Spans 1 to 78) would consist of a reinforced concrete deck slab supported on steel stringers with elastomeric bearings, which in turn would be supported on reinforced concrete piers with spread footings. The westbound roadway would consist of three 3.66 m (12’-0”) lanes. The eastbound roadway would transition from three to four lanes for Alternatives RA-5, BR-2, BR-3 and BR-5, with two 3.66 m (12’-0”) lanes for traffic continuing on the BQE and two 3.66 m (12’-0”) lanes for traffic exiting to the LIE (see Figure III-33, “Cross Section of Brooklyn Connector after Replacement”). The eastbound roadway for Alternative RA-6 would consist of three 3.66 m (12’-0”) lanes. For all Build Alternatives, the left and right shoulders would vary in both eastbound and westbound directions, with a minimum of 0.61 m (2’-0”) in most locations.



FIGURE III-33: CROSS SECTION OF BROOKLYN CONNECTOR AFTER REPLACEMENT

The new structure would be designed for MS23 (HS25) live loading. The existing vertical clearances, shown in Table II-33, would be retained or improved if feasible.

RAMPS

The new ramp structures in Brooklyn would consist of concrete slabs on grade for a majority of the length, with the slab supported on soil kept in place by reinforced concrete retaining walls. The portion of the ramps that connect to the elevated highway would likely be slabs on grade or a structure similar to the Brooklyn Connector. The exact configuration would be determined during final design. The Vandervoort Avenue entrance ramp would have two 3.66 m (12’-0”) lanes, a 1.98 m (6’-6”) right shoulder and a 1.07 m (3’-6”) left shoulder, for an overall roadway width of 10.36 m (34’-0”). Increasing the number of lanes on the entrance ramp from one to two lanes would improve operations at the Vandervoort Avenue/Meeker Avenue intersection by reducing queuing on the ramp and at the signalized intersection. The Meeker Avenue/Morgan Avenue exit ramp would have one 3.66 m (12’-0”) lane, a 1.98 m (6’-6”) right shoulder and a 1.07 m (3’-6”) left shoulder, for an overall roadway width of 6.71 m (22’-0”).

BROOKLYN AND QUEENS APPROACHES, AND MAIN SPAN OVER NEWTOWN CREEK

Alternatives RA-5 and RA-6 would rehabilitate the existing Brooklyn Approach (Spans 79 to 88), Queens Approach (Spans 90 to 100), and Main Span (Span 89), making steel repairs to the Warren trusses and bracing to correct localized corrosion. Based on a fatigue analysis, some riveted truss members are prone to cracking, so the rivets would be replaced by high strength bolts. The existing bridge deck, a concrete filled steel grid deck, would be replaced in kind. The existing crossbeams and stringers, which support the bridge deck, would be replaced with new stringers, and supported on the existing floorbeams. The existing steel rocker bearings that support the trusses would be replaced with new elastomeric or pot bearings. Modern traffic barriers would replace the existing steel fascia railings and median. Since the concrete pier columns and footings for the Brooklyn and Queens Approaches were found to be vulnerable in a seismic event, reinforcement is recommended.

The rehabilitated structure would be designed for MS18 (HS20) live loading. The existing vertical clearances, shown in Table II-33, would be retained or improved if feasible.



Although the existing structures would be rehabilitated, the existing trusses are non-redundant, and failure of a single truss member would cause a catastrophic failure. In addition, the reinforced concrete footings for the steel towers supporting the Main Span would remain partially in Newtown Creek. Therefore, the timber fenders and dolphins would be replaced to protect the foundations from ship and ice damage.

All of the Build Alternatives would include new bridge structures, either as a new parallel structure in the Rehabilitation Alternatives, or as a new bridge replacing the existing Brooklyn Approach, Main Span and Queens Approach for the Bridge Replacement Alternatives. The final bridge type would not be selected until the final design phase. However, based on the Bridge Replacement Type and Construction Impact Study prepared for the project (see Appendix E), it was determined that overhead construction without the use of large ground-based cranes would minimize disruption to nearby businesses and local streets. The Brooklyn and Queens Approaches would likely be precast concrete segmental bridges, supported on cast-in-place concrete piers (see Figure III-34, “Cross Section of Alternative BR-5 Concrete Segmental Replacement Bridge”). The foundations would likely be either large diameter drilled shafts or concrete filled steel pipe piles.

FIGURE III-34: CROSS SECTION OF ALTERNATIVE BR-5 CONCRETE SEGMENTAL REPLACEMENT BRIDGE

The Main Span over Newtown Creek could be almost any bridge type. The shoreline is basically open ground, and the new Main Span could be largely fabricated off site, barged to the site and lifted into place. Bridge types that were specifically studied for this project include concrete segmental and extradosed bridges (See Figure III-35, “Elevation of Extradosed Bridge”). Both bridge types are practical and economical selections. There has been keen interest expressed by the public for a signature span, and a cable stayed bridge has been considered. A cable stayed Main Span would add to the cost, but since the Main Span is a small portion of the total bridge length, the percentage increase in cost may not be great if an economical design is used. The final bridge type for the Main Span would be determined during



the final design phase. Depending on the height of any bridge structures (e.g., extradosed or cable-stayed bridge towers), coordination with the Federal Aviation Administration may be required to address possible effects on navigable airspace in accordance with Title 14 of the Code of Federal Regulations, Part 77.

FIGURE III-35: ELEVATION OF EXTRADOSED BRIDGE

The new bridge structure for Alternative RA-5 would be built on the eastbound side of the existing bridge, and would have three 3.66 m (12’-0”) lanes, a 1.22 m (4’-0”) left shoulder, a 3.05 m (10’-0”) right shoulder, and a 4.0 m (13’-1”) bikeway/walkway.

The new bridge structure for Alternative RA-6 would be built on the westbound side of the existing bridge, with roadway lane and shoulder widths similar to Alternative RA-5. No bikeway/walkway would be included with this alternative.

Alternatives BR-2, BR-3, and BR-5 would demolish the existing bridge and construct three new bridge structures with 3.66 m (12’-0”) lanes, 1.22 m (4’-0”) left shoulders, and 3.05 m (10’-0”) right shoulders. The three new bridge structures would include a four lane westbound bridge with a 4.0 m (13’-1”) bikeway/walkway, a two lane eastbound bridge for vehicles remaining on the BQE, and a three lane eastbound bridge for vehicles bound for the LIE. As outlined in the Bridge Replacement Type and Construction Impact Study (see Appendix E), demolition of the existing superstructure would be performed using overhead demolition methods. The existing piers would be demolished down to approximately 0.6 m (2 ft) below ground level.

The new bridge structures in all the Build Alternatives would decrease the vertical clearance over Newtown Creek from 38 m (124’-6”) to approximately 27 m (88’-5”) to improve traffic operations by decreasing the steep grades. As described in the Newtown Creek Navigation Analysis Report (see Appendix F), it was determined that lowering the bridge by 11 m (36 ft) would not impede marine navigation on the creek. A United States Coast Guard permit would be required for construction.

C.2.e. Hydraulics

This section describes the effects of each of the Build Alternatives on the hydraulics (any effect on the flow of water) of Newtown Creek. A description of water to be discharged to the creek is included in Section III.C.2.f and a description of the project’s effect on navigation within the creek is included in Section III.C.2.q.



Alternatives RA-5 and RA-6 would maintain the existing piers and the Main Span over Newtown Creek, with a lateral opening of 76 m (250 ft), which provides sufficient clear area for Newtown Creek to flow beneath the bridge. Both of the Rehabilitation Alternatives would also construct a new permanent bridge parallel to the existing bridge, either on the eastbound or westbound side. The piers of the proposed parallel bridge’s Main Span would be located upland of the existing piers resulting in no effect on this horizontal clearance. However, the elevation of the parallel structure would be lower than the existing bridge, resulting in a vertical clearance of 27 m (88’-6”) over Newtown Creek at MHW. Although the vertical clearance of the proposed parallel bridge over Newtown Creek is reduced by 11 m (36 ft) from the existing, sufficient clear area is provided for Newtown Creek to flow beneath the bridges, without affecting the hydraulics of the creek.

Alternatives BR-2, BR-3, and BR-5 include demolition of the existing bridge and piers and construction of new Main Spans over the creek. A lateral opening of 107.5 m (353 ft) from pier foundation to pier foundation would be provided through which the creek would flow. The bottom of the new structures would be 27 m (88’-5”) above Newtown Creek at MHW. Under Alternatives BR-2, BR-3 and BR-5, the pier location and the height of the Main Span above Newtown Creek would provide significant clear area for Newtown Creek to flow beneath the Main Span without affecting the hydraulics of the creek.

The proposed Main Span for all Build Alternatives would likely be constructed on pile supported foundations. The piles would extend 17.4 m (57 ft) and the pile cap would extend 4.6 m (15 ft) beneath the lowest elevation of the creek bed, thereby minimizing the susceptibility of the foundations to scour. During final design a scour analysis would be performed and the foundations designed to minimize scour potential.

C.2.f. Drainage

All of the Build Alternatives would result in an increase in the total stormwater runoff due to the addition of auxiliary lanes across the bridge. Table III-30 shows the estimated stormwater runoff per bridge segment for all five Build Alternatives and the No Build Alternative. For a detailed description of the bridge segments identified in the table, see Section II.C.1.o. Stormwater runoff estimates were developed by applying a runoff coefficient of 0.9 and a storm intensity of 168 mm (6.6”) of rainfall/hour over the surface area of the structure, in accordance with NYSDOT Design Guidelines.

TABLE III-30: ESTIMATED STORMWATER RUNOFF PER BRIDGE SEGMENT

Drainage Runoff Estimate [m3/s (ft3/s)]

Alternative Brooklyn

Connector Brooklyn

Approach Main Span Queens

Approach LIE

Interchange Total

Runoff

No Build 0.83 (29.28) 0.51 (18.06) 0.10 (3.68) 0.57 (20.26) 2.32 (82.03) 4.34 (153.31)

RA-5 0.95 (33.44) 1.12 (39.44) 0.18 (6.42) 1.26 (44.37) 2.24 (79.06) 5.74 (202.73)

RA-6 0.88 (31.24) 0.96 (33.86) 0.17 (5.88) 1.08 (38.08) 2.14 (75.68) 5.23 (184.74)

BR-2 0.95 (33.62) 1.18 (41.82) 0.27 (9.56) 1.31 (46.21) 2.22 (78.35) 5.93 (209.56)

BR-3 0.95 (33.56) 1.18 (41.58) 0.27 (9.56) 1.29 (45.62) 2.22 (78.35) 5.91 (208.67)

BR-5 0.94 (33.15) 1.14 (40.10) 0.27 (9.44) 1.37 (48.53) 2.25 (79.54) 5.97 (210.76)



All of the Build Alternatives would include construction of a new drainage system for collection and discharge of stormwater runoff. The proposed drainage system would be designed to supplement the existing New York City sewers and eliminate the conditions on the Brooklyn Approach, Main Span, and Queens Approach that allow stormwater runoff to free fall off the bridge to the ground below by providing for new storm sewers (where sewers do not exist) that outfall to Newtown Creek. As described in Section IV.B.3.k, discharge of stormwater to Newtown Creek would require a permit from the New York State Department of Environmental Conservation (NYSDEC).

A brief description of the proposed drainage areas and the approach for collecting runoff from each area, for the Build Alternatives, is provided below and shown in Figure III-36, “Drainage Plan (Brooklyn Connector),” Figure III-37, “Drainage Plan (Main Span),” and Figure III-38, ”Drainage Plan (Queens Connector).”

RUNOFF DIRECTED TO EXISTING STORM SEWERS IN BROOKLYN

Under all Build Alternatives, stormwater runoff from the portion of the Brooklyn Connector between station 1+050 (Apollo Street) and station 0+757 (Kingsland Avenue), would be collected in scuppers and downspouts and directed to the existing city sewer system via new sewer connections in Meeker Avenue.

RUNOFF DIRECTED TO NEWTOWN CREEK VIA PROPOSED SEWER

BROOKLYN AREA

Under all Build Alternatives, stormwater runoff from a portion of the Brooklyn Connector, the Brooklyn Approach, and the Main Span between roadway station 1+880 (mid-Main Span) and roadway station 1+050 (Apollo Street) would be collected in scuppers and downspouts and discharged to Newtown Creek via a new storm sewer and outfall constructed as a part of this project. The new sewer would be located beneath the footprint of the Brooklyn Approach and Brooklyn Connector from Apollo Street to Morgan Avenue. Additional information on proposed pre-treatment of stormwater is provided in Section IV.B.3.b.

QUEENS AREA

Under all Build Alternatives, stormwater runoff from the Queens Approach and Main Span, between roadway station 1+880 (mid-Main Span) and roadway station 2+519 (north of 54th Avenue and west of the BQE mainline) would be collected in scuppers and downspouts and discharged to Newtown Creek via a new sewer and outfall constructed as a part of this project. The new sewer would extend from Laurel Hill Boulevard to the creek and would be located beneath the footprint of the Queens Approach. Additional information on proposed pre-treatment of stormwater is provided in Section IV.B.3.b.

RUNOFF DIRECTED TO NEWTOWN CREEK VIA EXISTING 43RD STREET STORM SEWER AND OUTFALL IN QUEENS

Under all Build Alternatives, stormwater runoff from the Queens ramps north of station 2+495 (54th Avenue) and east of the BQE mainline would be collected in catch basins, scuppers, and downspouts, and directed to the existing storm sewer beneath 43rd Street, which outfalls to Newtown Creek.



The resulting stormwater runoff from the structure to each drainage system for each alternative is provided in Table III-31. See Section II.C.1.q for further information regarding the drainage system for the No Build Alternative.

TABLE III-31: ESTIMATED STORMWATER RUNOFF FROM THE STRUCTURE TO EACH DRAINAGE SYSTEM

Drainage Flow Estimate [m3/s (ft3/s)]

Alternative

To Existing Storm Sewers in

Brooklyn

To Newtown Creek via

Overland Flow

To Newtown Creek via Existing 43rd St.

Outfall in Queens

To Newtown Creek via

Proposed Sewer Total Runoff

No Build 0.42 (14.73) 1.60 (56.55) 2.32 (82.03) NA 4.34 (153.31)

RA-5 0.35 (12.52) N.A. 1.47 (51.80) 3.92 (138.41) 5.74 (202.73)

RA-6 0.32 (11.19) N.A. 1.37 (48.42) 3. 54 (125.13) 5.23 (184.74)

BR-2 0.35 (12.53) N.A. 1.46 (51.38) 4.12 (145.65) 5.93 (209.56)

BR-3 0.35 (12.53) N.A. 1.46 (51.38) 4.10 (144.76) 5.91 (208.67)

BR-5 0.35 (12.53) N.A. 1.46 (51.38) 4.16 (146.85) 5.97 (210.76)

The acquisition of additional right-of-way beyond the footprint of the structure would result in additional drainage flow to Newtown Creek via the proposed sewer. Based on the worst case right-of-way acquisition, the additional stormwater runoff from those additional properties would be 2.53 m3/s (89.2 ft3/s).

The amount of runoff directed to the existing city sewers would be reduced under the Build Alternatives by diverting a portion of the runoff currently discharged to the existing sewers to the proposed sewer. All remaining runoff not discharged to the city sewers would be discharged to Newton Creek via the proposed sewer and outfall constructed to Newtown Creek and new storm sewers and catch basins constructed within the right-of-way of the streets crossing beneath the Brooklyn Approach, Main Span, and Queens Approach.

C.2.g. Maintenance Responsibility

Maintenance of the local streets within the project area would continue to be the responsibility of NYCDOT while NYSDOT would continue to be responsible for maintenance of the Kosciuszko Bridge and its ramps, including all signage on the structure. Upkeep of the bridge scuppers and drainage pipes would also be NYSDOT responsibility. NYCDOT would also continue to be responsible for maintenance of the lighting on the Kosciuszko Bridge.

Maintenance of the new park areas, proposed for each alternative, would be the responsibility of NYCDPR.

The catch basins and the sewer and water mains in the project area would continue to be maintained by NYCDEP. Private utility owners including Consolidated Edison Company, Keyspan, Verizon, and Buckeye Pipeline, would continue to be responsible for maintenance of their utilities in the project area.

C.2.h. Maintenance and Protection of Traffic

Maintaining an efficient flow of traffic on the BQE throughout construction was a fundamental basis for the development and screening of Build Alternatives for the project and drove the

feis chapter 3 final 082008v6 - nysdot home...kosciuszko bridge project iii-84 september 2008...

Documents