Minneapolis Bridge Collapse Update

Law enforcement has revised the number of those killed downward to four, and video of the collapse has surfaced. It doesn't show the entire span unfortunately, and it would appear that the start of the collapse occurred off camera.



Hot Air has more information, including excerpts from engineering reports on the bridge.

Look for more hometown coverage from Lileks, Captain Ed, and Powerline.

A 2005 structural report on the bridge, which graded it structurally deficient is here.

UPDATE:
As I'm from the NYC metro area, I am well aware of the thousands of bridges, overpasses, and viaducts and have travelled over many of them over my life. Some are in extremely poor shape, but the City has been repairing or replacing some of the older bridges - 3d Avenue, Macombs Dam, and rebuilding others, including the Triborough, Whitestone, Throgs Neck, 59th (Queensboro), WillieB, Manhattan and Brooklyn. The Port Authority is also doing work on (or has completed work) on the Outerbridge, Goethals, and GWB. They've also done upgrades on the Holland and Lincoln Tunnels.

Rehab and constant maintenance is the only way to stay ahead of problems.

I expect Mayor Bloomberg to push the congestion pricing scheme again in the coming days, focusing on what the tax can do for infrastructure repair and maintenance - to avoid the MN situation. In this environment, I think he'd have a much better chance of getting people to agree to that tax.

UPDATE:
Investigators are focusing in on vibration and fatigue cracking as possible causes for the collapse.

Investigators looking into the cause of the Interstate Hwy. 35W bridge collapse are likely to focus on two primary causes -- vibration and fatigue cracking, the former chairman of the National Transportation Safety Board said in an interview early Thursday morning.
Jim Burnett said they should look at whether vibration from the construction work contributed to the collapse, or whether a train that was under the bridge at the time may have been moving, contributing vibration to the bridge.

"Vibration is one of things that cause cracking to propagate," he said. "They will be looking at that."

Burnett, who is in town for a Republican National Committee meeting, was watching the scene at 5 a.m. with other onlookers at the University Avenue SE. northbound entrance.

He also said he was intrigued by a 2001 University of Minnesota study that found signs of "fatigue cracking" in the bridge supports, though he noted that a later report apparently concluded that the bridge was in no immediate danger and did not need major repairs.

"I think that decision is going to come under new scrutiny," he said.

A 2005 federal study found that the bridge was "structurally deficient."

"A structurally deficient bridge might be one not adequate for the traffic it takes, but not necessarily dangerous," Burnett said. "But a lot of structurally deficient bridges are dangerous."

UPDATE:
The bridge design in Minnesota reminds me of a similar bridge designed over the Hudson River in Albany. The Patroon Bridge, which carries I-90, has had numerous problems with cracks over the years, and is monitored annually.

The Times Union took a close look at this bridge for a story published Jan. 14.

We reviewed inspection records obtained from the state Department of Transportation as the result of requests under the state's Freedom of Information Law and questioned state transportation engineers familiar with the Patroon Island Bridge and its issues.

The greatest concerns engineers have about this bridge aren't related to the unsightly crumbling concrete you can see from your car. DOT has undertaken an aggressive monitoring program to watch cracks in the structural steel below the road surface.

When necessary, contractors work to stem the damage in crack-prone areas by drilling holes that can stop horizontal cracks from growing and installing steel reinforcing angles to stabilize twisting floor beams.

The most recent inspection was completed in November 2006.

For now, DOT engineers say the extra care and attention are keeping the bridge in safe shape. Overall, it has a rating of 5 on a 7-point scale. That's the rating normally given to a bridge that functions fine with minor deterioration.

Still, all that attention costs money and valuable engineers' time, and the 1,783-foot-long Patroon, which spans the Hudson River between Albany and Rensselaer counties, is busier than ever.

The bridge has seen numerous other problems relating to cracks in the structural members and joints, in addition to the concrete spalling on the surface of the deck and railings. Replacing the bridge would top $100 million, so a regular maintenance program is in place to deal with the ongoing issues with cracks. Some of the problems have been addressed in prior repairs, but staying on top of the condition of the bridge is paramount to maintaining the safety of the public.

UPDATE:
NJ Governor Corzine has ordered the State DOT to inspect all bridges across the state and provide a report within 45 days. He said that any bridges deemed unsafe would be closed to traffic.

Corzine said New Jersey has 6,400 bridges, 2,400 of which are under state control. The other bridges are either under federal or local government control, but he said the state will look at all of them.

"I want to make sure that the conditions of our bridges has been monitored," Corzine said during a visit to the South Plainfield Senior Center.

He said he wants an interim report from the state transportation commissioner in a week and a final report in 45 days. Specifically, Corzine said he wants the report to detail bridge conditions, safety ratings, how often the bridges are inspected and the cost of needed repairs.

"If there are any unsafe bridges, they will be shut down," Corzine said. "Safety comes first."

I expect Corzine or the legislature to consider proposing an increase in the gas tax to fund the transportation trust fund to deal with the crumbling state transportation infrastructure, especially considering that New Jersey has one of the lowest motor fuels taxes in the country but has one of the densest concentrations of roadways and bridges in the country.

UPDATE:
Investigators are going to be reconstructing the bridge, much as they would do in an aircraft crash reconstruction.

Mark Rosenker, chairman of the National Transportation Safety Board, said today the investigation may take a year or more. The reassembly can help the probe, not unlike the way aviation disasters are treated.

"This will be a complex investigation ... the first thing we must do is recover the pieces."

Rosenker said that the head of the NTSB's materials lab in Washington, D.C., would arrive in Minneapolis Thursday afternoon to take part in the investigation.

He and Minneapolis Police Chief Tim Dolan put out a plea for members of the public who may have photographed the bridge collapse to provide their still photos and videotape to authorities.