Clark Bridge

Power Up

For all its functionality, at night the Clark Bridge glows as a work of art. Since 1994, the cable-stayed bridge has facilitated traffic flow across the Mississippi River between Black Jack, Missouri, a northern suburb of St. Louis, and Alton, Illinois. It replaces the old Clark Bridge, a two-lane truss bridge built in 1928, also named after explorer William Clark.

With four traffic lanes and two bike lanes, the new bridge 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 140 feet below bedrock. Only two piers support the bridge, which improves river navigation.

During every phase of construction, Wissehr played a major role in its electrification, overcoming winter’s intense cold on the river and the 1993 flood. As a subcontractor during the early stages, Wissehr electricians installed new traffic signals on highways leading to the bridge. They performed grounding and cathodic protection in the piers below water level as well as brought grounding electrode conductors to water level.

Throughout the entire project, they embedded conduits in the concrete structures. Wissehr bid and won the electrical prime contract to pull the miles and miles of cable through all the various conduits that they had installed as a subcontractor.

Wissehr installed the roadway lighting and decorative lighting, which consisted of some special fixtures that light the cable stays. Each suspension cable has two intense light fixtures with a very narrow beam spread that shine up along the cable to illuminate it. In addition, they installed architectural lighting on the concrete pylons, an aviation obstruction beacon system on the tops of the pylons and navigation lighting system below to protect the piers.

As you approach the Clark Bridge, after an evening drive under the stars along Alton’s Great River Road, and you’re awed by the bridge’s glowing presence, thank Wissehr.

Public Broadcasting Service produced a Nova documentary about the construction of the Clark Bridge. To purchase a copy of the program for home viewing, visit Shop PBS Online

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