THE BRIDGE-Maintaining span, support areas is big job for bridge staff|[6/21/05]
Published 12:00 am Tuesday, June 21, 2005
Look closely at the Old Mississippi River Bridge and you’ll see hundreds of what appear to be big, black bolts. They’re called rivets, and they are what hold the structure’s steel beams together.
“There are billions of them,” said bridge superintendent Herman Smith. They’re in good shape, or good enough after 75 years. “If they were all replaced, we could increase the strength of the bridge twofold,” Smith said.
It would cost millions of dollars and years to do that, he said. Instead, “What our engineers are looking at doing, in key places where there is the possibility of structural failure, is replace rivets with bolts,” Smith said.
There are more pressing issues facing the bridge. Commissioners appointed by the Warren County Board of Supervisors are scavanging for up to $6 million for erosion controls on the Mississippi side of the river. Earlier this month, the commission agreed to pay nearly $100,000 to stabilize some of the dirt that is threatening supports. That could take 60 to 90 days, but it’s temporary.
“The purpose of this project is to disturb as little as possible,” said ABMB engineer Lynn Wolfe.
Wolfe was hired by the commission in 2004 to study erosion problems at the upper bluff. He determined work was needed.
“We see this as critical to the life of the bridge,” he said.
Over the past six decades, engineers have noted movement by 20 feet at Navy Circle just north of the bridge and, lately, they have noticed large slides after heavy rains. In April 2003, Smith said, some damage was done when the city was drenched in 8 1/2 inches of rain. The east abutment, the concrete base where the roadbed meets the land, was exposed.
“It’s been exposed since that very morning,” Smith said.
Erosion problems are not new to the bridge, however. The first stabilization project was done in 1939, less than a decade after it opened.
Other work needed for the bridge includes repairing the expansion joints, which allow the structure to expand and contract during hot and cold temperatures. Emergency repair to one of the joints was authorized recently.
As big as the bridge is, it needs lots of room to “breathe.”
“It has to have expansion,” Smith said. “It’s just the way the bridge works.”
The bridge has been closed to vehicular traffic since 1998. Since then, many people in Vicksburg have said they want the bridge reopened to local traffic, but the width of the road has been deemed unsafe and supervisors have been firm in refusing to consider that option any longer. Instead, a $1.5 million proposal aims to turn the bridge into a park. That idea, opposed by the rail company that pays tolls for bridge maintenance, must win approval from county officials before anymore steps are taken.
THE SERIES
In recognition of the 75th anniversary of the opening of the U.S. 80 Bridge over the Mississippi River, The Vicksburg Post is spending a week looking at the old bridge, its operations and history. Many of the photographs accompanying the stories were taken by Post presentation editor Marty Kittrell, who gingerly took his camera 110 feet to the top of the span, offering rarely seen views.