Interstate 35W Bridge Research

Project Summary

The collapse of the Interstate 35W bridge over the Mississippi River on August 1, 2007, resulted in a tragic loss of life and a major disruption of the Twin Cities’ transportation system. Following the collapse, University of Minnesota researchers initiated several lines of research aimed at investigating the failure of the original bridge, analyzing the effects of the collapse on the rest of the traffic network, and developing enhanced sensor systems to monitor the health of the new I-35W St. Anthony Falls Bridge.

The original steel bridge was completed in 1967 and carried roughly 140,000 vehicles daily on four lanes of traffic in each direction. The new bridge opened to traffic on September 18, 2008—just over one year from the date of the collapse. The bridge is a key component of the freeway network serving the Twin Cities region and the entire state.

Additional information on the collapse and reconstruction of the bridge is available on the Minnesota Department of Transportation Web site, including the final report of the National Transportation Safety Board investigation into the causes of the collapse, background on the construction and inspection history of the original bridge, and aerial and ground photographs.