MoDOT - Old bridge was safe

Last Thursday's bridge blast took down more of Cape Girardeau's old Mississippi River bridge than expected, collapsing 76-year-old steel beams beyond the blast area. Spectators wondered if they had been playing Russian roulette in recent years every time they drove across the narrow span.

Missouri Department of Transportation officials insist motorists were never in danger when they traveled across the aging bridge.

"You have to remember that the deck was off the bridge," said Stan Johnson, Missouri Department of Transportation engineer.

The deck was constructed with a steel grid filled with concrete, which "provided a lot of lateral bracing," Johnson said. The old bridge lost a lot of its rigidity once the deck was removed, he said.

Johnson compared the bridge to a wood frame house. "It is kind of rickety until you add the plywood. That bridge is the same way," he said.

The demolition contractor, Midwest Foundation Corp. of Tremont, Ill., removed the bridge deck before using explosives to bring down sections of the bridge. The first bridge blast occurred Aug. 3, followed by another on Aug. 26 and the latest one last week.

Thursday's blast closed the river to barge and boat traffic for more than 48 hours while crews on barge cranes hauled the steel debris out of the navigation channel.

Since the river reopened to traffic Saturday afternoon, crews have continued to work to clear debris from the channel. Johnson said the remaining debris in the navigation channel might be removed from the river by Friday.

Plans still haven't been made on how to remove the remaining sections of the collapsed bridge, which are not in the navigation channel.

Thursday's blast sliced up a 671-foot-long main span, dropping the steel into the river's main navigation channel.

But the blast also set up a chain reaction that damaged the remaining spans of the bridge. The blast caused the other 671-foot section of the main span to collapse in the middle, tearing out part of a concrete pier and sending one end of the remaining 314-foot span crashing into the water.

Johnson said earlier demolition blasts may have weakened the structure. In addition, the contractor had cut through some of the metal structure to make it easier to demolish, he said.

As for the ongoing salvage work, crews are moving the steel debris to the Illinois shore where it is being chopped up and hauled off for recycling.

The continuing salvage work hasn't posed problems for barge traffic, U.S. Coast Guard officials said.

The contractor moves the barge cranes out of the way to allow towboats to pass, said Lt. Wayne Chapman with the Coast Guard's Marine Safety Office in Paducah, Ky.

"I haven't heard any complaints from the towboat captains," he said.

mbliss@semissourian.com

335-6611, extension 123