Flood Mitigation Program at the Hugh L. Carey Tunnel and Queens Midtown Tunnel

After Superstorm Sandy filled the Hugh L. Carey Tunnel with 60 million gallons of water and submerged 40 percent of the Queens Midtown Tunnel with saltwater damaging much of the infrastructure of both tunnels, OHLA USA’s subsidiary, Judlau Contracting, Inc., was selected as the design-build contractor to facilitate a comprehensive flood mitigation program to protect the entrance and exit plazas of both tunnels as well as the Governors Island Ventilation Building to the established Design Flood Elevation. The $2 million mitigation program at the tunnel plazas provided for at least two independent lines of flood protection at each of the four dedicated tunnel plazas, a deployable tunnel portal flood protection system at each tunnel portal, and a protected perimeter of existing retaining walls and additional deployable and permanent barriers.

The design incorporated gates that integrate with the architecture of the walls leading up to the tunnel entrances. The four bronze-colored floodgates are 29 feet long, 14 feet high, and 22 inches thick. When the tunnel is operating in normal conditions, the flood gates sit on jacks mounted to the sidewalk at the side of the portals. In an impending storm event, a two-person crew can deploy the floodgates with the help of a forklift or front-end loader. The crew will also remove the steel road plates covering the gate receiver trough. The complete closing operation of the flood gates takes approximately 30 minutes.

The scope of work also included the design and construction of reinforced pump room walls and floors with flood-proof hatches, reinforced building slabs, flood-proof manholes, and associated drainage features, such as tide gates and flood-resistant utility systems. Judlau’s schedule reduced the RFP-prescribed timeline for substantial project completion by six months, enabling the design-build team to deliver the project within only two years.