Deciphering Causes

While the search for victims continues at a very slow pace due to near zero visibility conditions in the Mississippi River, investigators are still examining the scene of the collapse of the I35W bridge in Minneapolis and are wondering why a section of the bridge appears to have shifted 50 feet off axis as it collapsed. That may lead to how and why the bridge collapsed, though it will take time:

What's getting investigators' attention is the way the southern part of the bridge fell in a video they've already examined -- recorded by a security camera near the bridge's north end -- and the way the section settled after the collapse.

"It appears that it has shifted approximately 50 feet to the east and when we compare that to what we've seen in the rest of the bridge -- the rest of the bridge appears to have collapsed in place, " said NTSB Chairman Mark Rosenker, who is leading a 19-member team charged with determining the cause of the accident.

"We're going to take a look at any unique design factors that could have created that shift...for whatever reason."

It's not the answer to the mystery of why the bridge fell, but a step forward, Rosenker said.

The NTSB will also examine three more videos provided by the Army Corps of Engineers, one of which may show another view of the bridge falling, Rosenker said. Investigators aren't optimistic the other two will show anything because they weren't pointed at the bridge.

On Thursday, U.S. Transportation Secretary Mary Peters notified state transportation departments to immediately inspect all bridges of the same design as the one that collapsed Wednesday on Interstate 35W into the Mississippi River in Minneapolis.

There are over 700 bridges of similar design, including several along the New York State Thruway and I90.

Investigators continue to pore over the paper trail on the bridge, and other states are taking up inspections of their bridges and infrastructure to see if there are similarly deficient structures that need immediate attention.

Money does not appear to be an issue here. According to the Minnesota Department of Transportation, federal transportation funding increased 46% for 2005-2009 over the prior funding period, which was set at the end of the Clinton Administration.

U.S. President George Bush signed a $286.4 billion six-year transportation reauthorization bill Aug. 10, 2005 that covers federal fiscal years 2004-09.

Although the details of the reauthorization package are still being reviewed, Minnesota state and local governments can expect to receive about $3.5 billion in federal transportation funding through 2009, an increase of about 46 percent (or about $1.1 billion) over the previous six-year bill.

So, if the bridge needed to be replaced or significantly repaired, the money was available.

However, as the investigators are looking closer at the structure itself, it appears that the collapse may have been due to design defects - the lack of redundancy built into the bridge itself. Those are decisions made decades earlier - both as a result of costs to build, and assumptions over bridge use, maintenance and replacement at the end of its useful life.

UPDATE:
Congress has voted on measures to provide funding to rebuild the bridge. The measures voted yesterday would amount to $250 million. Technical amendments are likely, and may increase the overall funding to $255 million.