2007 — Aug 1, Interstate 35W Bridge Collapse and vehicles fall, Minneapolis, MN — 13

— 13  Cook. “Towards an Emergency Response Report Card…I-35W Bridge Collapse.” 2009.

— 13  Delatte. Beyond Failure: Forensic Case Studies for Civil Engineers. 2009, p. 211.

— 13  NTSB. HAR. Collapse of I-35W Highway Bridge, Minneapolis, MN.  Nov 14, 2008.

— 13  USFA. I-35W Bridge Collapse and Response, Minneapolis, Minnesota.  Aug 2007, p. 1.

— 12  National Highway Traffic Safety Administration. FARS 1975-2010 Fatality Analysis.

 

Narrative Information

 

NTSB: “About 6:05 p.m. Central Daylight Time on Wednesday, August 1, 2007, the eight-lane, 1,907-foot-long I-35W highway bridge over the Mississippi River in Minneapolis, Minnesota, experienced a catastrophic failure in the main span of the deck truss. As a result, 1,000 feet of the deck truss collapsed, with about 456 feet of the main span falling 108 feet into the 15-foot-deep river. A total of 111 vehicles were on the portion of the bridge that collapsed. Of these, 17 were recovered from the water. As a result of the bridge collapse, 13 people died, and 145 people were injured.

 

“During its investigation, the Safety Board learned that 24 under-designed gusset plates, which were about half the thickness of properly sized gusset plates, escaped discovery in the original review process and were incorporated into the design and construction of the bridge.

 

“On the day of the collapse, roadwork was underway on the I-35W bridge, and four of the eight travel lanes (two outside lanes northbound and two inside lanes southbound) were closed to traffic.  In the early afternoon, construction equipment and construction aggregates (sand and gravel for making concrete) were delivered and positioned in the two closed inside southbound lanes.  The equipment and aggregates, which were being staged for a concrete pour of the southbound lanes that was to begin about 7 p.m., were positioned toward the south end of the center section of the deck truss portion of the bridge near node U10 and were in-place by about 2:30 p.m.

 

“Shortly after 6 p.m. a lateral instability at the upper end of the L9/U10W diagonal member led to the subsequent failure of the U10 node gusset plates on the center portion of the deck truss.  Because the deck truss portion of the I-35W bridge was considered non-load-path-redundant, the total collapse of the deck truss was unavoidable once the gusset plates at the U10 nodes failed.

 

“The NTSB examined other possible collapse scenarios – such as corrosion damage found on the gusset plates at the L11 nodes and elsewhere, fracture of a floor truss, pre-existing cracking in the bridge deck truss or approach spans, temperature effects and shifting of the piers – and found that none of these played a role in the accident.

 

“As a result of its investigation, the NTSB made nine recommendations to the Federal Highway Administration and the American Association of State Highway and Transportation Officials dealing with improving bridge design review procedures, bridge inspection procedures, bridge inspection, training and load rating evaluations.” (NTSB, Nov 14, 2008)

 

USFA: “In 1967, the Interstate 35W Mississippi River Bridge in Minneapolis opened to traffic. The bridge was 1,907 feet long, had 14 spans, and by 2007 carried a daily average of 140,000 total vehicles north and south over four lanes between University Avenue and Washington Avenue. The vehicle count made it one of the busiest bridges in the country over the Mississippi River, and one of three principal arteries into downtown Minneapolis, a city with one of the highest population densities in the Midwest.

 

“Just after 6 p.m. on the evening of August 1, 2007, the 40-year old bridge collapsed into the river and its banks without warning, killing 13 and injuring 121 others. At the time, there were approximately 120 vehicles, carrying 160 people, on the bridge. The impact of the fall broke the span into multiple planes of broken steel and crushed concrete—cars, buses, and trucks all resting precariously along guardrails or suddenly unprotected edges, crashed into other vehicles, partially embedded in the muddy river bank, or dropped precipitously into the river.”  (USFA.  I-35W Bridge Collapse and Response, Minneapolis, Minnesota (USFA-TR-166).  Aug 2007, p. 1)

 

Cook Abstract: “On August 1, 2007 at about 6:05 pm, during the height of the evening rush hour, the I-35W Bridge collapsed into the Mississippi. The collapse was unanticipated, surprising the response community and public alike and robbing them of any warning that would have allowed for the closing of the bridge. Based on the characteristics of the collapse, the response should have been an exceptionally complicated endeavor. However, in spite of the very complicated scene confronting the response community, the response activities have been praised as being very successful. This article examines the literature on emergency response to determine what characteristics are thought to be necessary for success. It then examines the emergency response to the I-35W Bridge collapse based on those criteria. It concludes with an analysis of what failed, met expectations, and really succeeded in the response.” (Title page.)

 

Sources

 

Cook, Alethia H. “Towards an Emergency Response Report Card: Evaluating the Response to the I-35W Bridge Collapse.” Journal of Homeland Security and Emergency Management, Vol. 6, Issue 1, Article 59, 2009.

 

Delatte, Norbert J. Jr.  Beyond Failure: Forensic Case Studies for Civil Engineers. Reston, VA:  American Society of Civil Engineers Press, 2009.

 

National Transportation Safety Board. Highway Accident Report. Collapse of I-35W Highway Bridge, Minneapolis, Minnesota, August 1, 2007 (NTSB HAR-08/03; NTIS PB2008-916203). Washington, DC: NTSB, 2008. Accessed at: http://www.ntsb.gov/publictn/2008/HAR0803.htm

 

National Highway Traffic Safety Administration. Partial Data Dump of Crashes Involving 10 or More Fatalities, by Year, Fatality Analysis Reporting System (FARS) 1975-2009 Final and 2010 ARF. Washington, DC: NHTSA, pdf file provided to Wayne Blanchard, 1-26-2012.

 

National Transportation Safety Board. “NTSB Determines Inadequate Load Capacity Due to Design Errors of Gusset Plates Caused I-35W Bridge to Collapse.” NTSB News, November 14, 2008.  Accessed at:  http://www.ntsb.gov/Pressrel/2008/081114.html

 

United States Fire Administration. I-35W Bridge Collapse and Response, Minneapolis, Minnesota (USFA-TR-166).  Emmitsburg, MD:  USFA, August 2007, 60 pages. Accessed at: http://www.usfa.dhs.gov/downloads/pdf/publications/tr_166.pdf