A decade after Superstorm Sandy flooded New York City’s largest transit rail yard complex, the combined Stillwell Avenue Yard, Avenue X Yard and Coney Island Yard now boast enhanced resilience to withstand future storms. The $524-million project included a 12,000-ft-long, 15-ft-high perimeter flood wall that can withstand a Category 2 storm surge, with an additional 3 ft to account for sea level rise and freeboard, says the team. The flood protection system also features eight large-scale swinging structural steel custom vehicular flood gates, stackable barriers at four railroad tracks and two pedestrian access gates.

Poor soils and numerous at- and below-grade obstructions required careful placement of piles and reconsideration or redesign of numerous foundations to avoid damaging critical existing infrastructure. Wherever possible, the team said it reinforced and integrated existing structures into the perimeter protection system. Two sides of the historic Traction Motor Shop were tied into the concrete flood wall system by reconstructing portions of the historic masonry facade using self-consolidating concrete to augment the existing concrete masonry unit backup wall.

Photo courtesy STV

According to the submission, one key challenge was designing and constructing a 4,000-ft-long elevated track cable bridge, located within a structural steel box truss to support yard personnel, traction power and communication infrastructure. Through strategic placement of columns, sequencing, offsite fabrication and construction in large segments, bridge installation was done with minimal disruption to yard operations. New communication and fiber optic cables routed to the cable bridge above the flood elevation allowed for easy future installations, while the traction power system was upgraded with a new contact rail and appurtenances.

The project included hardening existing structures, restoration and replacement of damaged power infrastructure and an internal drainage system that ensures dry conditions for 24-hour rainfall in non-storm surge situations. The multiyear year effort logged 625,000 work hours with no lost-time accidents or recordable incidents, the team notes.