Rockman's Ramblings

Personal Reflections on I-35 Bridge Collapse in Minneapolis

On January 15, the National Transportation Safety Board released a safety recommendation letter report to the FHWA related to the I-35W bridge collapse in Minneapolis Minnesota that claimed the lives of 13 people and injured 145. The safety recommendations are based on the findings of an interim report from the FHWA Turner-Fairbank Highway Research Center  that some gusset plates, components of the steel trusses, were undersized (not thick enough). This deficiency was confirmed to be a flaw in the design and not construction-related based on review of the original drawings from the 1960s and inspection of the wreckage. Whether this was a calculation error or a drafting error will perhaps never be known as only portions of the original design calculations were located. But the point is that it was never caught by any reviewers.

When this event first happened back on August 1, I remember being very shaken up by it. After my initial sadness for the victims of the accident, my first thought as a geotechnical engineer was: “were the foundations at fault.” As more information came out, it quickly became evident that the failure did not have anything to do with the foundations but that it was related to the superstructure of the bridge. But this still was something that profoundly affected me. (Continues…)