- The Washington Times - Thursday, May 30, 2002

Robert J. Healy is building a bridge.
Mr. Healy, deputy director for the Office of Bridge Development for the Maryland State Highway Administration in Baltimore, is one of the many people involved with the construction of the new Woodrow Wilson Bridge, which is at the midpoint of Interstate 95 over the Potomac River.
"There won't be anything quite like it anywhere," Mr. Healy says. "The people who live in the shadow of the Brooklyn Bridge are very proud of it. We hope we can give local people a bridge and that they can be proud."
Bridges first were built during the Roman Empire. Since then, modern technology has influenced the construction of the structures. Although the materials used may have changed during the years, bridges still serve the same main purpose: to connect people from one place to another.
When starting to make plans to construct the new bridge, Mr. Healy says, engineers first explored various alternatives for about 12 years, such as the type of bridge and its location. They researched the most environmentally safe proposals and estimated the funding needed.
In 1998, during the Woodrow Wilson Bridge design competition, a plan was chosen from Parsons Transportation Group, based in Baltimore. The concept outlines a box girder bridge with V-shaped pier supports. Steel boxes placed on top of the V-shaped supports tie them together. The design offers the appearance of a true arched bridge, such as the Arlington Memorial Bridge or the Key Bridge, but it is not actually an arched bridge. The shape made by the V-shaped pier supports lacks the continuous arch that is present in classic arched bridges.
The proposal expands the current six-lane structure into 12 lanes. The new bridge will consist of two 6,075-foot-long bascule bridges, which allow moving ships to pass beneath them. A bascule bridge features a drawbridge, which is counterbalanced so that when one end is lowered, the other is raised. At the highest point, there will be about 70 feet between the water and the bridge, which is an increase of 20 feet from the existing bridge. The current bascule bridge opens about 260 times a year. With the additional space, the new bridge will have to open just about 65 times a year.
The original Woodrow Wilson Bridge opened In 1961 and was designed to carry about 75,000 vehicles per day, Mr. Healy says. Today, that same structure carries about 195,000 vehicles per day. The bridge under construction is designed for 300,000 vehicles a day. With the expansion of the lanes, the new bridge's width will be about 234 feet, with 15 feet between the two spans.
"What sets a bridge apart is that it's designed to take moving loads," Mr. Healy says. "A building just sits there."

The new Woodrow Wilson Bridge will sit on steel piles, which will be about 200 feet below the bottom of the river or the ground of the shoreline. Workers dredged the river to create a channel of about 10 feet of water to hold their boats and barges. Then, steel piles were driven into the ground by a hydraulic hammer. Concrete caps are placed over the top of the piles to hold them together, creating a pedestal.
These pedestals give a base on which to build the rest of the bridge. They will support the 17 V-shaped piers, which is a reduction from the 57 piers on the existing bridge. Builders plan to create four pedestals per V-shape, which is two for each span. Having fewer piers will make it more aesthetically pleasing and easier for large ships to pass through, Mr. Healy says.
The foundation work probably will be completed in the next year. Then a crane will place the legs of the V-shaped piers on the pedestals. Temporary metal ties will hold up the legs of the piers until a concrete top is placed on them. Then a steel box will be placed on top of the V-shaped piers and a mold will be built to cast a concrete deck.
After the first span of the bridge is completed, the old bridge will be demolished, Mr. Healy says. The new portion will be used by vehicles as the second span is being built. The entire project will cost about $600 million and probably be completed about 2007. This construction is part of a larger project that includes 7 miles of surrounding highway and four interchanges in Maryland and Virginia, costing more than $2 billion.
"It's was exciting to see the bridge emerge from the water," Mr. Healy says.

Sameh S. Badie, assistant professor at the George Washington University in Northwest, says the V-shaped design of the Woodrow Wilson Bridge is one of many types of bridges that have developed over the years.
Mr. Badie, who holds a doctorate in structural engineering and is a professional engineer, says that because of the scarcity of wood during the Roman Empire, bridges were made of stone in an arched form. Some of the bridges, the aqueducts, also had channels to move water through them.
During the 1700s and 1800s, the British began to build cast-iron arch bridges. Wrought iron eventually was used because the cast iron couldn't hold the heavy loads. In the 1900s, they began to use steel because it was stronger than wrought iron or cast iron.
When the Brooklyn Bridge in New York City was built, engineers used steel because it was the strongest material available at the time. When it was finished in 1883, it was the longest arch suspension bridge in the United States, with steel cables hung from each tower and tied to huge anchors at the end of the bridge. When the Golden Gate Bridge in San Francisco was completed in 1937, it became the longest arch suspension bridge in the world with about 4,200 feet between its two towers.
Another type of bridge is the cable-stayed bridge, which looks similar to a suspension bridge, says Mr. Badie. Both have decks that hang from cables, and both have towers. The difference is that in cable-stayed bridges, the cables are connected to the towers, which carry the load without anchors at each end. An example would be the Akashi Kaukyo Bridge in Kobe and Awaji-shima, Japan. It has the longest main span in the world, with 6,527 feet between towers.
Mr. Badie says the most important thing about any bridge is that it connects people from one place to another.
"Without bridges, it would be very expensive to travel," he says. "They are crucial structures for transportation."

Shane Rixom, a structural engineer with BridgePros in Jacksonville, Fla., is working on building the Wonderwood Bridge for the Jacksonville Transportation Authority. He says bridges are the perfect example of why learning math and science are important.
For instance, many bridges are based on types of triangles. On a cable-stayed bridge, the tower comes out of the water, and the cables come down to the deck, forming the hypotenuse or long end of a right triangle. If this isn't constructed correctly, the bridge will collapse.
Because bridges are such gigantic undertakings, Mr. Rixom says many people travel to a certain area specifically to see a bridge.
"Bridges are some of the most unique structures in the world," he says. "They can really define an area or city."
Herbert Rothman, one of the owners of Weidlinger Associates in New York City, says that because bridges are landmarks, some fear they will be targets of terrorism. Mr. Rothman, who has been an engineer since 1944, says engineers try to design the structures in a way that prevents such disasters. They identify the vulnerabilities of the bridges and attempt to eliminate them, if possible.
Often engineers will harden a bridge's materials so that it should withstand a blast. They also might create a "sacrificial wall" outside the bridge's structure that would absorb an explosion and leave the main portion intact.
These usually are expensive solutions, Mr. Rothman says. Placing video cameras on bridges to monitor the area is a less expensive possibility. Lighting bridges well also helps reveal suspicious visitors.
Aside from terrorism, engineers have other concerns, such as preventing the collapse of bridges caused by accidents. For instance, on Sunday morning on the Arkansas River in Webbers Falls, Okla., an out-of-control barge hit the Interstate 40 bridge and destroyed a 500-foot portion of the highway, which led to at least 13 deaths, according to Associated Press.
Whatever methods are taken to secure bridges, Mr. Rothman believes that caring for the structures should be a priority. He says the prosperity of a region is directly related to its transportation methods.
"They are a major component of a transportation system," he says. "Think of what it would be like to spend two weeks on horseback to get somewhere. Without bridges, we go back to the Stone Age."



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