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Minnesota Department of Transportation (MDOT) officials say that the new I-35W bridge is ahead of schedule and should be open before this Christmas. The completion date is December 24th, but with $27 million in incentives for early completion, MDOT expects the project to be done early.

MDOT Metro-District Engineer Khani Sahebjam said during a panel discussion at the Transportation Research Board’s recent annual meeting that one of the hardest things MDOT had to deal with was the assumption people made about the cause of the bridge failure. “The people assumed that it was a lack of inspection, done by non-qualified people,” said Sahebjam.

An interim recommendation released by the National Transportation Safety Board (NTSB) points to a design flaw in the gusset plate as the cause of the bridge failure, but the investigation is ongoing. The recommendation is “for all non-load-path redundant steel truss bridges within the National Bridge Inventory, require that bridge owners conduct load capacity calculations to verify that the stress levels on all structural elements, including gusset plates, remain within applicable design requirements, whenever planned modifications or operational changes may significantly increase stresses.”

NTSB Chairman Mark Rosenker emphatically stated that the cause of the collapse was not due to inspection failures. “What caused the [gusset plate] failure has yet to be determined. It is important to understand the bridge inspections would not have identified the error in the design plate, said Rosenker.