PITTSBURGH — The National Transportation Safety Board initial review doesn't identify the cause of a recent bridge collapse in Pittsburgh.
But the preliminary report issued Monday concluded it began at the structure’s west end.
The report says investigators found no primary fractures in sections of welded steel girders they examined that were considered “fracture critical.”
The Forbes Avenue bridge gave way early Jan. 28 and sent a city bus and four cars to the bottom of a ravine.
Ten vehicle occupants were injured. There were no fatalities.
The NTSB says it's extracting bridge components for closer study. A final report could take more than a year.