Friday, May 24, 2013

I5 Bridge Might Have Faulted on Same Structural Defect as I35W

This photo was taken one week before the I35W bridge in Minneapolis, MN collapsed on August 1, 2007.  The gusset plate which was blamed to be the direct cause of failure was highlighted.
Although the Department of Transportation of State of Washington considered the bridge not 'structurally deficient', based on the pictures, it was build with the same technology as the I35W bridge which collapsed in Minneapolis, MN on August 1, 2007. The I35W bridge had been cleared of any risks from all past inspections, including a through study conducted by an associate professor at University of Minnesota one year before its collapse. After the I35W bridge accident, a large number of bridges built around the time were considered structurally deficient.

I5 bridge over Skagit River, AP Photo
Comparing to the picture of the collapsed I5 bridge, it would be hard for one not to recognize the place it failed, and the same gusset plates that are in use to connect the bridge.

While the I35W bridge collapsed, the bridge was going through a maintenance upgrade with construction material and vehicles on the bridge. Combined with bumper to bumper traffic in afternoon rush hours, it was considered a very heavy load. Officials blamed the I5 bridge's collapse to a heavy load truck which scratched a few girders.

According to Wikipedia, the I5 Skagit River Bridge opened in 1955. The I35W Mississippi River Bridge opened in 1967. At the time, engineers did not fully understand the properties of steel used to make the gusset plates that connect the bridge. Bridges built later used thicker gusset plates therefore carries no risks, or so as we were told.

It is too soon to tell what exactly caused the collapse of the I5 Bridge over Skagit River, while we are still within hours of the accident. Pointing fingers at the truck driver does not release the duty and responsibility of government officials by any means.

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