I-35W Mississippi River Bridge Collapse

I-35W Mississippi River bridge also known as 'Bridge 9340', completed in 1967 was an eight-lane steel truss arch bridge. Minnesota Department of Transportation was performing its maintenance and was Minnesota's fifth–busiest, carrying 140,000 vehicles daily.  
On the eve of August 1, 2007 during rush hour the bridge disastrously collapsed into the river and riverbanks beneath. In all 13 people were killed and around 100 people were injured.  Approximately 100 vehicles were involved, sending their occupants and 18 construction workers up to 115 feet (35 m) down to the river or onto its banks. Northern sections fell into a rail yard, landing on three unoccupied and stationary freight train cars.

The seven-county Minneapolis-Saint Paul metropolitan area and emergency response personnel, charities, and volunteers carried out the rescue operations immediately after the collapse. A concrete reason for the collapse of the bridge was not known but investigations revealed that a design error might have caused the bridge to collapse.

The bridge was designed by Sverdrup & Parcel to 1961 American Association of State Highway Officials (AASHO, the precursor to AASHTO) standard specifications. The construction contracts, worth in total more than US$5.2 million at the time, went to Hurcon Inc. and Industrial Construction Company, which built the steel trusses and deck.
Construction began in 1964 and the bridge opened to traffic in 1967. When the bridge fell, it was still the most recent river crossing built on a new site in Minneapolis.