Possible design flaw found in collapsed U.S. bridge

A week after a deadly bridge collapse, U.S. Navy divers cut through tangled debris with underwater torches and saws on Wednesday in the search for victims while investigators identified a possible flaw in the 40-year-old span's design.

Possible design flaw found in collapsed U.S. bridge
The August 1 rush-hour collapse of the Interstate 35W bridge hurled vehicles into the Mississippi River 65 feet below, with many tumbling onto the bridge's crumpled concrete deck.

Reacting to the disaster, officials demanded inspections of potentially suspect bridges across the United States amid renewed calls to shore up the country's aging infrastructure.

Five people were killed in the bridge collapse, a death toll that was confirmed within a day of incident. Eight other probable victims are listed as missing.

The recovery process has been slowed by huge slabs of steel-reinforced concrete and dangerous chunks of debris submerged in the river's swift, turbid waters. In some cases, divers had to use their fingertips to read license plates.

"This is going to be a process of having to, most likely, pull these vehicles out and do a long-term extraction, taking apart the vehicle to recover evidence, (and) any (human) remains," Minneapolis Police Capt. Mike Martin told reporters.

National Transportation Safety Board investigators said they had found a potential design problem with gusset plates, or steel plates that tie together angled steel beams of the bridge's frame.

Investigators are trying to verify loads and stresses on these plates at specific locations as well as the materials used to construct them.

Officials stressed the finding is preliminary and would not say exactly where the plates were located or whether failure would have caused the collapse.

"We are continuing to make progress on this investigation, and each area of inquiry gets us closer to ultimately determining the cause of this tragedy," National Transportation Safety Board Chairman Mark Rosenker said in a statement.

Out of some 100 people injured, only a handful remained in hospitals with one in critical condition.

City officials have called the large number of survivors miraculous.

For the families of the missing it has been an agonizing wait. Members of Minneapolis' large Somali immigrant community are grieving over the presumed death of a 23-year-old nursing student, who was pregnant, and her 2-year-old daughter.

Minnesota officials were quickly laying the groundwork for replacing the vital eight-lane bridge, which had been the state's busiest with 140,000 vehicles crossing it each day.

Construction bids were due on Wednesday and officials hoped to choose a contractor within weeks to build a new bridge by the end of 2008, with the help of $250 million promised by the federal government. One proposal called for two spans of five traffic lanes each, with room for light rail or buses.

It was unlikely a new bridge could be completed before the Republican Party convention in September 2008, to be held in neighboring St. Paul.

Last Mod: 08 Ağustos 2007, 23:58
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