Contradicting the National Transportation Safety Board’s report that blamed too-thin gusset plates for the Aug. 1, 2007, collapse of the Minneapolis Interstate 35W bridge, an independent analysis concluded that rusted, frozen roller bearings were pivotal in the tragedy that killed 13 people and injured 145.  The roller bearings prevented thermal expansion and caused a truss chord to fail, triggering the gusset-plate failure that led to the bridge collapse.  The analysis employed forensic bridge information modeling and was presented to victims’ families. It will be deployed in an anticipated lawsuit against the engineers and contractor involved in the design and maintenance of the bridge.