OasisLMS

Abstract: Contract 3 was the third and final contract in NYSDOT’ s $1.7B Hunts Point Access Improvement Project to provide improved vehicular access between the wholesale commercial businesses on the Hunts Point Peninsula and the Sheridan and Bruckner Expressways. Contract 3 required complex temporary traffic staging in order to construct new ramps and interconnections of active roadways between the prior improvements made in Contracts 1 and 2 and a replacement pedestrian bridge over Bruckner Boulevard. The ramps were nestled between a more than 100-year old underground MTA NYCT tunnel and through the fill of a large gravity retaining wall bordering a sunken Amtrak corridor. The ground conditions were defined based on an exploration program consistent with NYSDOT and AASHTO standards and included Fill and Glacial Soils overlying decomposed and competent Schistose bedrock. Bedrock varied between 20 and 43 feet below grade. Performance of new foundation elements to support the ramps was not allowed to exert additional stresses on either structure. The selected foundation systems consisted of 36-inch, 72-inch and 84-inch diameter drilled shafts socketed in rock and 18-inch diameter micropiles. The drilled shaft foundations were used within the influence of the NYCT tunnels as they could be encased in isolation sleeves to prevent the transmission of lateral stresses onto the tunnels. Beyond the influence of the tunnel, micropiles were installed in a low-headroom and congested site. Micropiles were also used within the limits of influence of the Amtrak retaining walls and were analyzed under revised surface loading conditions to maintain stresses on retaining structures to below pre-existing conditions. All rock sockets were visually observed by the designer and both drilled shafts and micropiles were load cell tested axially to confirm the nominal bond stresses used in design.

Mr. Alireza Ayoubian; Mr. PAUL B. PIZZIMENTI

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