|
|||||||||||||||||||||||||||||||||||||
|
Visitors Guide to
the
Often called the "Super Bridge," the Clark Bridge links Highways 367 and 67 in Missouri to Alton, Illinois. It replaced the old Clark Bridge that served the area from 1928 to 1994. Design work on the new cable-stayed bridge was started in 1985, and construction began in 1990. The bridge, which has four traffic lanes and two bike lanes, spans 4,260 feet across the Mississippi River. It is made of 8,100 tons of structural steel, 44,100 cubic yards of concrete and more than 160 miles of cable wrapped with four acres of yellow plastic piping. Pilings that support the bridge were driven more than 140 feet below bedrock. Design criteria based on wind testing and geological studies were used to help make the bridge earthquake resistant. Total cost of the bridge was 118 million dollars, including the demolition of the old bridge.
The Clark Bridge was named after William Clark who, with Meriwether Lewis in 1804, commanded the two year 4,000 mile exploration of the Louisiana Purchase territory up the Missouri River into the Pacific Northwest. The Lewis and Clark Expedition set off just a few miles south of the bridge near Hartford, Illinois. Cable-stayed bridges look similar to suspension bridges, with both having roadways that hang from cables and towers. But the two bridges support the load of the roadway differently. In suspension bridges, the cables ride freely across the towers, transmitting the load to the anchorages at either end. In cable-stayed bridges, the cables are attached to the towers that bear the load. Cables can be attached to the roadway in two ways. In a radial pattern, cables extend from several points on the road to a single point at the top of the tower. In a parallel pattern, cables are attached at different heights along the tower, running parallel to one other. The Clark Bridge cables are attached in a radial pattern. Even though cable-stayed bridges look futuristic, they are an old idea. The first known sketch of a cable-stayed bridge appears in a 16th century book called Machinae Novae, but it wasn't until the 20th century that engineers began to build them. Because steel was scarce in post-World War II Europe, the design was perfect for rebuilding bombed out bridges that still had standing foundations, and many examples of this type of bridge can be found in Western Europe. Only recently have cable-stayed bridges have begun to be erected in the United States.
|
|||||||||||||||||||||||||||||||||||||
Learn more about the
