On This Date In History...
Saturday, August 01, 2009
2004 satellite Photo of the I-35 bridge.
The I-35 bridge is on the far left,
the bridge to the right is the 10th Avenue Bridge.
(Public Domain photo by US Geological Survey.)
The central span collapsed first followed by the adjoining spans. Most of the truss structure and deck fell into the river and on to the river banks. The northern section fell onto rail yards and crushed several freight cars that were parked on the tracks.
An amazing set of images was captured by a Corps of Engineers security camera, located at the entrance of the parking area of the Lower St. Anthony Falls Lock & Dam, showing the collapse of the bridge.
About 100 vehicles were involved in the collapse. Cars and construction workers, who were on the bridge, fell the 115 feet to the surface. 93 people were rescued from the bridge and an additional 20 people were pulled from the icy waters of the Mississippi River. Thirteen people perished in the collapse. A school bus, which you can see in the photo below, rested against a concrete barricade, near the edge of the bridge remnants, in a most precarious position. 60 students were aboard the bus, on their way home from a field trip. Jeremy Hernandez was a 20 year old advisor to the group. He kicked out the emergency door and aided the children to escape the bus. One staff member was seriously injured as were 10 of the students, but all survived the ordeal.
The National Transportation Safety Board investigated the collapse. On January 15, 2008, the NTSB announced that the collapse had been caused by the failure of a gusset plate that was undersized for the bridge. In addition, over the years, deck resurfacing added layers of concrete, increasing the dead load by 20%. Construction vehicles, parked on the bridge at the time of the collapse, added 578,000 pounds of sand and water on the vehicles themselves. All were parked over the weakest spot on the bridge at the time of the collapse.
The replacement for the collapsed structure, the St. Anthony Falls Bridge, opened on September 18, 2008, months ahead of schedule and under budget.
Note: All the images used in this article are either public domain, taken by employees of the US Government during the course of their work, or used freely under rules of the GNU Free Documentation License.