Architecture News

Storm Surge Barriers Work

By Aileen Cho, Scott Lewis, Tom Sawyer

Storm Surge Barriers Work
The Thames Barrier protects London. Designed by Rendel, Palmer and Tritton, the barrier consists of nine concrete piers and gates stretching 1,700 feet across the river. The piers house hydraulic machinery that can raise 60-foot-tall gates in 30 minutes to block the surge tide coming up the Thames Estuary. When not in use, the gates rest in concrete sills flush with the river bottom, allowing ships to pass. The sills exert no direct load on the riverbed but sit in ledges in the pier sides to prevent differential settlement. The specially designed barriers, called rising sector gates, are steel box spans stiffened by internal webs and diaphragms. There are six rising sector gates, four are 200 feet wide and two measure 103 feet. The remaining four gates are of conventional falling radial design. Construction began in 1975, was largely completed by 1982, and cost $700 million. The Barrier has been closed 119 times to date.
Photo courtesy Wikipedia

Storm Surge Barriers Work
The Oosterscheldekering (Eastern Scheldt Storm Surge Barrier) is the largest of 13 structures making up the Delta Works that protect southern Holland. The Delta Works were initiated in response to the North Sea Flood of 1953 that killed 1,835 people in the Netherlands. Construction began in 1976, was completed in 1986, and cost $2.4 billion. It has been fully closed 24 times to date.
Photo courtesy Wikipedia

Storm Surge Barriers Work
The Maeslantkering surge gates protect Rotterdam, in the Netherlands, the world’s third busiest port in terms of cargo tonnage. Construction was completed in 1997 and cost $450 million. The barrier has only been closed once so far, in 2007.
Photo courtesy Wikipedia

Storm Surge Barriers Work
The St. Petersburg Flood Prevention Facility Complex protects St. Petersburg, Russia, a city of 4.8 million residents. The barrier consists of an embankment across the Neva River estuary, topped by a six-lane ring road connecting the mainland with Kotlin Island and the city of Kronstadt. Construction began in 1978, but was halted in 1987, when the job was 65 percent complete. When the project restarted in 2003, Halcrow Group led a team that included Dutch firm DHV BV and the Norwegian firm Norplan that reviewed the original design and updated it in accordance with new design codes and changes in scope. It was completed in 2011, and cost $3.85 billion.
Photo courtesy Wikipedia

Storm Surge Barriers Work
The Fox Point Hurricane Barrier protects Providence, Rhode Island, which is located at the head of Narragansett Bay. It consists of two 800-foot-long rockfill wing dikes that extend from either end of a 680-foot-long concrete gravity section across the Providence River. The barrier’s crest is 25 feet above mean sea level, and was designed to protect the city from a hurricane-driven tide of 20.5 feet above mean sea level. Providence’s geography makes it unusually vulnerable, because it’s downtown business district is below the level of extremely high tides experienced during hurricanes. When bay water plugged up the river’s mouth the surge would spill over and flood the business district. Therefore the barrier has to do more than hold off the bay tide. The Fox Point Barrier (as well as ones in New Bedford, Mass. and Stamford, Conn., which follow) was built in response to devastating hurricanes in 1938 and 1954.
Photo courtesy USACE

Storm Surge Barriers Work
The New Bedford Hurricane Barrier protects New Bedford, Massachusetts. It was built to protect 1,400 acres of highly developed industrial and commercial property. The barrier was completed in 1966, and cost $18.2 million.
Photo courtesy USACE

Storm Surge Barriers Work
The Stamford Hurricane Barrier protects Stamford, Connecticut. It consists of 13,000 feet of earth and armor-stone embankments and concrete walls rising 17 feet above mean sea level, and a 35-foot-tall steel gate. It was completed in 1969 at a cost of $11 million.
Image courtesy USACE

Storm Surge Barriers Work
The Marina Barrage protects low lying areas of Singapore. The barrage is a 1,150-foot-long reinforced concrete structure, with nine 100-foot-wide steel crest gates. It lies across the Marina Channel, at the confluence of five rivers. Construction was completed in 2008 and cost $173 million.
Photo courtesy CDM

Storm Surge Barriers Work
The Inner Harbor Navigation Canal-Lake Borgne Storm Surge Barrier. The city of New Orleans addressed deficiencies in its storm surge defenses that were painfully revealed by catastrophic surge flooding from Hurricane Katrina in 2005, by strengthening and completing a 50-year-old project to build a ring of perimeter defenses to protect against storms with surge elevations with a 1 in 100 probability of occurring in any given year. The largest component of $14.3 billion worth of new construction put in place in the seven years after Katrina is a $1.3-billion, 26-foot-tall, 1.8-mile-long surge barrier with three movable navigation gates that now stretches across the western end of Lake Borgne, a funnel-shaped body of water open to the Gulf of Mexico on the city's eastern flank. The wall is constructed of 1,284 concrete cylinder piles 66 inches in diameter, 144 feet long, and driven to 130 feet. The wall is braced on the protected side by 660 steel-cylinder batter piles, placed every second plumb. The 36-inch diameter steel piles are driven to 230 feet into the soft bottom of Lake Bourne. The operable gates consist of two 75-foot-wide, 42-foot-tall sector gate leaves that form an armored door to a 150-foot-wide navigable passage through the northern end of the barrier. A second bypass barge channel is closed by another 150-foot-wide sector gate. A third, recreational vessel channel is closed by a 56-foot-wide vertical lift gate. The Lake Borgne Surge Barrier ties into floodwalls and levees at either end and works in concert with yet another new surge barrier and lift gate complex at the northern end the Inner-Harbor Navigation Canal, which links the navigable channels to Lake Pontchartrain to the north. The perimeter system was most recently tested in August 2012, as it successfully blocked a storm surge from Hurricane Isaac and performed as designed.
Photo courtesy Wikipedia

Storm Surge Barriers Work
MOSE is a flood barrier under construction, which is intended to protect Venice, Italy. The barrier consists of a series of gates, which, once completed, will close off the three entrances to the Venice Lagoon to isolate it from high Adriatic Sea tides that have submerged the historic city repeatedly. Caissons will house oscillating buoyant flap gates that will pivot from the seabed about five times a year. Rows of hinged steel box gates will form the barriers.
Photo courtesy Wikipedia

Storm Surge Barriers Work
The Eider Barrage is located at the mouth of the Eider River on Germany’s North Sea coast. It is a reinforced concrete structure 790 feet long, consisting of a vehicular tunnel, flanked on both sides by sets of five 130-foot-wide steel gates. Nearby is a 245-foot-long, 45-foot-wide lift lock to accommodate fishing vessels and pleasure boats. The decision to build the barrage was made in the wake of the North Sea Flood of 1962, which destroyed 60,000 homes and killed more than 300 people. Construction was completed in 1973, at a cost of 170 million Deutschmarks.
Photo courtesy Wikipedia

The Thames Barrier protects London. Designed by Rendel, Palmer and Tritton, the barrier consists of nine concrete piers and gates stretching 1,700 feet across the river. The piers house hydraulic machinery that can raise 60-foot-tall gates in 30 minutes to block the surge tide coming up the Thames Estuary. When not in use, the gates rest in concrete sills flush with the river bottom, allowing ships to pass. The sills exert no direct load on the riverbed but sit in ledges in the pier sides to prevent differential settlement. The specially designed barriers, called rising sector gates, are steel box spans stiffened by internal webs and diaphragms. There are six rising sector gates, four are 200 feet wide and two measure 103 feet. The remaining four gates are of conventional falling radial design. Construction began in 1975, was largely completed by 1982, and cost $700 million. The Barrier has been closed 119 times to date.

Storm surge barriers work—up to a point; that point being the surge height  for which they are designed.   But even when overtopped, experts are banking on the barriers mitigating the  kind of run-away disaster that befell New Orleans during Hurricane Katrina in 2005.   One thing is for sure, though. The absence of storm surge barriers can  amount to no protections worthy of the name, as New York City learned Oct.  29 as Hurricane Sandy rolled ashore.  

Exposed towns, cities and even nations, such as The Netherlands, have slowly  and quietly been building up storm surge defenses to protect themselves for  decades, averting millions of dollars in damages as a result.   For example, Superstorm Sandy had swelled water levels to 9.5 feet as it  approached Providence, R.I., but thanks to the Fox Point Hurricane Barrier,  standing 26.7 feet high, that city avoided potentially millions in dollars  in damages.  

“I believe even if Providence had been hit directly, it would have been  fine,” says John MacPherson, deputy manager for the U.S. Army Corps  Engineers’ Cape Cod Canal Field Office. “When the Corps designed the  project, they took meteorological readings [and planned for a] worst-case  storm. The 1944 storm had the most energy off shore. They modeled that storm  hitting Providence coming up the bay as a direct hit, and generated a water  level to design for.”  

The 700-foot-long concrete barrier extends west across the Providence River.  It includes three 40-foot-high, 40-foot-wide tainter gate openings that prevent  floodwaters from entering the bay when closed. Two 10- to 15-foot-high  earth-filled dikes with stone-protected slopes flank each side. The eastern  dike is 780 feet long and the western dike is 1,400 feet long.  

Built in 1966, for about $15 million, the barrier “has prevented loss of life  and property time and again," says New England district spokesman Timothy  Dugan. In fiscal year 2011, the Corps of Engineers staff operated the  barrier for flood control on 12 occasions during coastal storms.   Devastating events, including a 1938 storm with a surge of about 17 feet,  prompted the city to ask the Corps to build the barrier, says MacDugan.

  Because of a series of storms between 1849 and 1936, Congress passed a  series of Flood Control Acts. The act of 1955 authorized construction of the  Providence barrier.   MacPherson says the city of Providence is responsible for operations and  maintenance of components located outside the river banks, such as the dikes  that flank each side and five vehicular street gates and five sewer gates.  Five large pumps pass accumulated water back over the dam and back out to  Narragansett Bay. The 55-foot-long pumps, 10 feet in diameter, can pass 630,000  gallons per minute.

Jurisdictions that are blessed with natural landforms that limit areas of  vulnerability to relatively short gaps between headlands have accomplished a  lot of protection with a relatively modest bit of engineering and  construction. But other jurisdictions, like New Orleans and the Netherlands,  with long reaches of high exposure, and flat coasts riddled with bays, lakes,  and lowlands, have been forced to build sprawling defenses to protect their  economies and populations.  

In most, if not all cases, the will to build storm surge defenses arose from  the mud, death, and heartbreak of disasters, such as the flooding of the  Dutch lowlands in 1953 or the catastrophe in New Orleans in 2005.   The events in New Orleans spawned a new discipline for designing systems to  protect large geographic areas from storm surge. Using now available super computing capabilities, scientists and engineers have, for the first time,  begun not to rely on historic records to estimate worst-case scenarios, but  on science and statistical-probability risk modeling of the storm surge -generating potential of the hurricane environment.