Hurricane Barriers: U.S. Engineering Solutions

waterway delta cut with a manmade barrier with openings
The Surge Barrier also called The Great Wall of Louisiana in New Orleans. Photo by Mario Tama/Getty Images (cropped)
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Fox Point Hurricane Barrier, Providence, Rhode Island

photo of bridge / open hurricane barrier in Providence, Rhode Island
Fox Point Hurricane Barrier, Providence, Rhode Island. Image by Lane via flickr.com, Attribution-NonCommercial-NoDerivs 2.0 Generic (CC BY-NC-ND 2.0) (cropped)

In Rhode Island, Hurricane Sandy's 2012 mighty storm surge was blocked by a 1966 piece of engineering. The technology of hurricane barriers is an investment for any region, but see how they work.

The Fox Point hurricane barrier is in East Providence, Rhode Island, situated across the Providence River, which flows into Narragansett Bay. It is 3,000 feet long and 25 feet high. It was constructed between 1960 and 1966 to protect the city from a storm tide of 20 feet above sea level.

The system consists of three Tainter gates, five pumps for river water, and two 10- to 15-foot high stone and earth levees or dikes along the river's bank. At a cost of $16 million (1960 dollars), state and local government paid only 30 percent of the cost while the federal government subsidized most of the cost of the hurricane barrier system.

How Does It Work?

Three Tainter gates, also called radial gates, can close to provide a half mile long, 25-foot high barrier between the City of Providence and the waters from Narragansett Bay. Water flowing down the Providence River to the sea is pumped out as it builds up behind the closed gates. The pumping station, 213 feet long and 91 feet wide, is constructed of reinforced concrete and brick. Five pumps have a capacity of pumping 3,150,000 gallons of river water per minute into Narragansett Bay.

Each Tainter gate is 40 feet square and weighs 53 tons. They are curved outward toward the Bay to break the impact of the waves. That are lowered by gravity at 1.5 feet per minute—it takes approximately 30 minutes to lower them. Because the heavy gates work against gravity when they are opened, it takes about two hours to raid them. They are powered mechanically by three horsepower electrical motors; if necessary, the gates can be lowered and raised manually.

Does a Hurricane Barrier Need a Pumping Station?

The design of any hurricane barrier depends on conditions. The pumping station at Fox Point is an important element to protecting the City of Providence. Without pumping out river water when the river is "dammed" by the gates, a reservoir would form and flood the city—just what Providence is trying to avoid.

Is a Hurricane Barrier a Dam?

Yes, and no. A dam certainly is a water barrier, but dams and reservoirs generally are not constructed for emergency use only. The sole purpose of a hurricane barrier is for protection from a storm surge or storm tide. The City of Providence has defined two central functions for Fox Point:

  1. "to retard high tides from potential storm surges in Narragansett Bay"
  2. "to maintain river flow such that water levels do not get too high behind the barrier"

What is a Storm Surge or Storm Tide?

A hurricane is a low-pressure center. Over land, low-pressure centers are not strong enough to move earth. However, low-pressure centers that are over water can actually push and move the water. Hurricane-force winds blow water not only creating waves, but also creating a dome or surge of high water. Along with a normal high tide, a storm surge can create an extreme storm tide in addition to the waves blown by severe hurricane wind. Hurricane barriers provide protection to anticipated storm tides.

Is a Storm Surge a Tsunami?

A storm surge is NOT a tsunami or tidal wave, but it is similar. Storm surge is an abnormal sea level rise, usually caused by extreme weather. The super-high tide also has waves, but the waves are not as dramatically high as a tsunami. Tsunamis are literally "harbor waves" caused by an underground disturbance, like an earthquake. Extreme flooding is the result of both events.

Living Near Water

When we look at a map of where people live, it's not difficult to imagine how vulnerable life and property can be to severe weather. Although constructing tsunami-proof buildings along the shorelines is an option, a rising storm tide can be relentless. The U.S. National Hurricane Center has provided a Flash animated example of a Storm Surge (Flash plug-in required). In this animation, storm surge along with pounding waves are no match to the small barrier protecting the structure.

Government Partnerships

Like any construction project, a need must be acknowledged and funding must be realized before architecture and construction can begin. Before the Fox Point, the City of Providence was threatened every year. In September 1938, the New England Hurricane caused $200 million property damage and 250 deaths with only 3.1 inches of rain. In August 1954, Hurricane Carol caused $41 million property damage with flood tides at high tide, 13 feet above normal. The Flood Control Act of 1958 authorized construction of a barrier at Fox Point. The U.S. Army Corps of Engineers (USACE) took control on February 2010, saving the City of Providence hundreds of thousands of dollars each year. The City maintains the dike and levee system. In 2011, the barrier was used twelve times.

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The Tainter Gate

Open tainter gate at the hurricane barrier in Providence, Rhode Island
Open Tainter Gate at Fox Point Hurricane Barrier, Providence, Rhode Island. Photo © Jef Nickerson, Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0), flickr.com

The tainter gate was invented in the 19th century by American engineer and Wisconsin native Jeremiah Burnham Tainter. The curved gate is attached to one or more truss-like, triangular framework pieces. The wide end of the triangle framework is attached to the curved gate, and the apex point of the truss rotates to move the gate.

The tainter gate is also known as a radial gate. The water pressure actually helps move the gate up and down. The end effect is similar to the vertical Watergates in Japan, but the engineering is much different. See how it works in a YouTube Animation by Arif Setya Budi and also an animated GIF provided by the Dunn County Historical Society, Wisconsin.

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The Vertical Lift Gate

vertical gate in
A Vertical Gate in the Inner Harbor Navigation Canal Lake Borgne Surge Barrier in New Orleans, Louisiana. Photo by Julie Dermansky/Corbis via Getty Images (cropped)

A vertical lift gate is similar to a Tainter gate in that it raises and lowers to control the flow of water. While a Tainter gate is curved, however, a vertical lift gate is not.

The gate shown here, the Bayou Bienvenue gate, is part of a massive $14.45 billion project in New Orleans—the Inner Harbor Navigation Canal - Lake Borgne Surge Barrier, also called The Great Wall of Louisiana. The concrete barrier wall built by the U.S. Army Corps of Engineers is nearly two miles long and 26 feet high.

Floods and storm surges are not unique to the United States nor to North America. Throughout the world engineers have found ways to control flooding. In an era of extreme weather, this type of problem-solving is a thriving area of engineering study.

Sources

  • Emergency Management Agency, City of Providence [accessed November 5, 2012]
  • Fox Point Hurricane Barrier Facts, PDF document from the City of Providence at www.providenceri.com/efile/705 [accessed November 5, 2012]
  • Update Report for Rhode Island, U.S. Army Corps of Engineers, New England District, July 31, 2012 at www.nae.usace.army.mil/news/Reports/ri.pdf. [accessed November 5, 2012]
  • PDF Document - IHNC - LAKE BORGNE SURGE BARRIER, U.S. Army Corps of Engineers, Updated June 2013 [accessed August 28, 2017]