Visitors Guide to
The Clark Bridge
connecting Alton, Illinois with Missouri
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
and Clark Expedition set off just a few miles south of the bridge near Hartford,
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
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