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Minnesota Bridges: I-35W Bridge

Minnesota Bridges

The I-35W Mississippi River bridge (officially known as Bridge 9340) was an eight-lane, steel truss arch bridge that carried Interstate 35W across the Saint Anthony Falls of the Mississippi River in Minneapolis, Minnesota. During the evening rush hour on August 1, 2007, it suddenly collapsed, killing 13 people and injuring 145. The bridge was Minnesota's third busiest, carrying 140,000 vehicles daily. The NTSB cited a design flaw as the likely cause of the collapse, noting that a too-thin gusset plate ripped along a line of rivets, and asserted that additional weight on the bridge at the time of the collapse contributed to the catastrophic failure. Within a few days of the collapse, the Minnesota Department of Transportation (Mn/DOT) planned a replacement bridge, the I-35W Saint Anthony Falls Bridge. Construction was completed rapidly, and it opened on September 18, 2008. (Wikipedia)

I-35W Bridge Collapse


August 1, 2007: Shortly after 6 pm, the I-35W Bridge collapses with over 80 motor vehicles on it at the time.

August 4, 2007: Mn/DOT issues a request for qualifications for a Design Build Contract for the I-35W Bridge replacement project. Congress authorizes about $250 million to rebuild the 35W bridge.

August 20, 2007: The body of the 13th and final victim of the I-35W Bridge collapse is recovered from the Mississippi River.

August 23, 2007: MnDOT releases the request for proposal for the new bridge over the Mississippi..

September 11, 2007: The Minnesota Legislature holds a special session; legislation passed includes several provisions related to the bridge collapse.

September 14, 2007: MnDOT receives technical proposals from four companies: Ames/Lunda, C.S. McCrossan, Flatiron/Manson and Walsh Construction/American Bridge.

September 18, 2007: MnDOT receives financial proposals.

October 5, 2007: City of Minneapolis passes resolution that grants approval of MnDOTs proposed bridge layout.

October 8, 2007: MnDOT awards new bridge contract to Flatiron/Manson.

October 15, 2007: Transportation Contingent Advisory Group gives MnDOT permission to spend an additional $60 million through 2/08. This amount is short of the $195 million requested.

October 16, 2007: MnDOT is sued over selection of winning bidder. The lawsuit alleges that the bidding process unfairly favored Flatiron/Manson. Suit requests that bridge construction be halted. (Sayer and Phillippi vs Minnesota Department of Transportation)

October 31, 2007: Judge rejects restraining order that would halt bridge construction. (Sayer and Phillippi vs Minnesota Department of Transportation)

November 1, 2007: Actual construction of new bridge begins.

November 29, 2007: Govenor and legislators announce the creation of "I-35W Emergency Hardship Relief Fund". This fund will provide $1 million in financial assistance to the victims of the 35W bridge collapse and their families. Victims and their families will be eligible for up to $10,000 in lost wages.

December 19, 2007: Minnesota Legislature's Joint Committee to Investigate the Bridge Collapse announces it has authorized the spending of up to $500,000 to the law firm Gray Plant Moody for an investigation into MnDOT and the I-35W Bridge collapse. The report is due in May.

January 11, 2008: The National Transportation Safety Board's (NTSB) on-going investigation uncovers an error in the original design process that resulted in undersized gusset plates on some of Bridge 9340's main trusses. On January 15, 2008, the board issues Safety Recommendation H-08-1, dealing with load capacity calculations for non-load-path-redundant steel truss bridges in the United States. These findings were released in the Federal Highway Administration's interim report, Adequacy of the U10 and L11 Gusset Plate Designs for the Minnesota Bridge No. 9340 (I-35W Over the Mississippi River).

March 5, 2008: The NTSB issues Structural Investigation Group Chairman Factual Report 08-015 (Materials Lab). On March 17, 2008, a NTSB update states that excess construction weight was placed above the earlier-reported too-thin gusset plates.

February 19, 2008: The Office of the Legislative Auditor releases an updated analysis of their 1997 highway spending report.

May 9, 2008: Governor Pawlenty signs a $38 million package to compensate bridge victims for their injuries and losses.

May 21, 2008: The Joint Committee to Investigate the Bridge Collapse releases their report, Investigative Report to Joint Committee to Investigate the I-35W Bridge Collapse.

September 18, 2008: The new bridge opens.

November 14, 2008: The National Transportation Safety Board (NTSB) issues their report.

(credit: Minnesota Legislative Reference Library)

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