Kew Gardens Interchange Infrastructure and Operational Improvement Project – Bridge 3 Demolition

Siefert Associates, LLC prepared working drawings for Halmar International to demolish a portion of an existing 63’ long concrete arch bridge spanning over the Grand Central Parkway in Queens, NY. Prior to saw cutting the portion of the concrete arch bridge to be demolished, the existing earth fill above the bridge was removed. Once the fill was removed, excavators saw cut along the length of the bridge, through the full thickness of the arch. After saw cutting was complete, excavators then began removing the saw cut portion of the arch in 5-foot-wide strips, starting from the apex of the arch, and working their way down to the existing abutments. Since the longitudinal saw cut was not parallel to the longitudinal reinforcing bars in the arch bridge, and the saw cut portion of the bridge could not be investigated on a per-foot width, Siefert Associates modeled the concrete arch bridge, and analyzed the structure in its saw cut state. The self-weight of the arch bridge and soil pressure at the abutments were considered. The portion of the bridge to remain was determined to be stable and structurally sound to support live traffic. The partial demolition of this existing concrete arch bridge was completed so that construction of the adjacent bridge structure could begin.