NTSB releases update on investigation into Fern Hollow Bridge collapse
PITTSBURGH (AP/KDKA) - The National Transportation Safety Board released an update on Thursday into the investigation of the Fern Hollow Bridge collapse nearly a year ago.
An agency update on the failure of the Fern Hollow Bridge said its engineers are examining "multiple fractures" found on the bridge's legs. All four legs have been scanned to enable further analysis.
The span dropped a bus and four cars some 100 feet into a ravine, injuring several people hours before President Joe Biden visited the city to promote a massive infrastructure law. The span carried Forbes Avenue over Frick Park, Fern Hollow Creek and Tranquil Trail.
A new bridge opened to traffic last month after design and construction were fast-tracked. One lane in each direction is open, but the full return is still a few months away.
The NTSB says that in addition to making 3D scans of portions of the collapsed bridge and assembling documentation, they have also been conducting mechanical and metallurgical tests that will soon be complete.
Results will be compared to specifications from the bridge's original design.
A preliminary report issued a year ago concluded the collapse began at the structure's west end and said there had been no primary fractures in sections of welded steel girders considered "fracture critical."
The NTSB said the latest 2,137-page update is just factual information collected by investigators and shouldn't be used to draw the probable cause of the collapse, which will be issued in a final report at a later date.
