BARGING Through

Lunda spans the Mississippi

Cass Street Bridge

By Brendan O'Brien

Photo courtesy of Lunda Construction Co.

Lunda Construction Co. tamed the Old Man while building a $22 million bridge across the Mississippi River in La Crosse.

"There were a lot of variables because you have the river that is going to go up or down," said Larry Lunda, owner of Lunda Construction. "When you are building this, you don't know what the final river stage is going to be."

The company worked with the U.S. Army Corps of Engineers and the U.S. Coast Guard to successfully calculate all the factors that went into floating the bridge into place. They had to consider buoyancy, weights and river heights five months prior to erection.

"You have to be fairly exacting in your calculations and your hunches," Lunda said.

Their hunches were right.

"When they floated it in, they had about 4 inches of clearance, so they were dead on," Lunda said.

The 1,700-ton main span was built downstream to stay out of the way of the daily barge tows and recreation boats that make up the river traffic. The bridge's arch was assembled in five months on falsework on barges out of the Mississippi River's channel.

If the arch had been constructed at the eventual bridge location, "barges would have had difficulty getting through," Lunda said. "Even if they could get through at some point, it could have been a potential hazard because if you have winds, then they get sideways and knock it out, and now your arches are in the water."

To combat buoyancy issues and the ever-changing weight of the structure during construction, Lunda added a series of adjustable water counterweights to the support barges.

	Project Name: Cass Street Bridge Location: La Crosse Submitting Company: Lunda Construction Co., Black River Falls General Contractor: Lunda Construction Co. Engineers: Earth Tech, Madison, civil engineer, and Wisconsin Department of Transportation, civil engineer Owner: Wisconsin Department of Transportation Project Cost: $22 million Start Date: December 2002 Completion Date: June 2004

"Every time we put on another piece of arch, it lowered the barge," Lunda said. "When we put down weight on one corner of the arch, it is going to have a tendency to twist, and then our next piece of the arch was going to be out of alignment.

"So [the project managers] came up with the idea of building boxes that were watertight on the barges that … would distribute the weight."

Lunda was given 24 hours to float the arch in place on the new piers. River traffic was restored 14 hours after the project began.

In addition to the span, the project consisted of construction of two abutments, 10 piers, retaining walls and approach grading.

To preserve the natural surroundings during the project, the company brought in mollusk specialists to dive and relocate endangered aquatic life, such as higgins' eye clams.

"The clams were catalogued and moved to another location so they wouldn't be hurt," Lunda said.