Building a barrier is one thing but having it function during a real storm is another. On December 26, 2011, more than a year after the Saint Petersburg barrier was finished, winds in a heavy winter storm funneled a wall of water into Neva Bay. Engineers closed all the navigation and sluice gates for 12 hours. “That’s when we learned that the barrier really works,” Forsyth says. Engineers have also successfully closed and opened the gates during tests in the middle of winter, when the water leaning against the structures is capped with a half a meter of ice.
Graeme and Goldstick hope that the two systems will not be similar in one respect. The Saint Petersburg design sat on shelves for decades, and after an initial phase of construction the project was stalled for years before it was then revived and completed. If New York City wanted to build the Outer Harbor Gateway, the engineering studies, design and construction could all happen within eight to 10 years, Goldstick says. He notes, however, “I’ve never seen the federal government or local regulators move quickly enough to allow that kind of timing to happen.” He adds that environmental studies of how the barrier could impact water flow and therefore life in the bay could take on the order of a decade—as could raising the funds. Critics might also object to the plan, saying the money could be better spent to flood-proof all kinds of structures in the city itself against sea level rise and smaller storms, which they contend are much more likely in the future than another superstorm surge.
To fully protect New York, a second, smaller barrier would have to be built northeast of the city, across the Long Island Sound. (Halcrow has not proposed a design for that location.) Experts outside of Halcrow say that the two barriers together, allowing for inflation over such a long time span, could cost from $10 billion to $20 billion.
The gateway design could include a six-lane highway on top of the barrier (as in Saint Petersburg), which would connect central New Jersey to the city’s borough Queens and to Long Island, a potential boon to commuters and tourists. If the road were approved, Goldstick notes, part of the project’s cost could be covered with federal highway funds, or money from investors if the highway was a toll road.