The I-35W Bridge in Mississippi was an arch bridge constructed of steel tuss, eight lanes long. The bridge passed Interstate 35W over the Mississippi River. Built in the 1960s, the bridge lasted nearly 40 years, until it abruptly collapsed in August 2007, 13 people were found dead and 145 others were injured (Stambaugh and Cohen, 2007).
According to LePatner (2010), flawed structures have led to a failure. However, a further investigation found that the metal plate defined by the builders was too small and could not be used as a junction for multiple girders. Further, the bridge had increased weight from the additional concrete structures that were installed to separate the lanes, increasing strain on the weak spots Investigations also found that corrosion or age could have caused of the problem. The bridge type was “fracture critical” meaning it had no redundancy and the failure of any part could lead to a collapse.
The National transport and Safety board stated that the likely cause was a design flaw caused by a gusset plate ripped along the rivets contributing to the catastrophic failure (LePatner, 2010).Historically, the bridge experienced a black ice phenomenon, when the temperatures reached below −30 °F (−34 °C).This identified the bridge as a dreadful cold weather spot because of the formation of the black ice layer. The state used embedded nozzles that were temperature sensitive and sprayed the bridge with a solution of potassium acetate to reduce the formation of the black ice. There is a possibility that the potassium acetate corroded the structural supports contributing to the collapse (Stambaugh and Cohen, 2007).
References
LePatner, B. B. (2010). Too big to fall: America’s failing infrastructure and the way forward. New York: Foster Pub.
Stambaugh, Hollis, and Harold Cohen. I-35W Bridge Collapse And Response, Minneapolis, Minnesota, August 1, 2007. [Emmitsburg, Md.]: FEMA, U.S. Fire Administration, 2008. Print.
