Study of Pittsburgh bridge collapse looking at leg fractures

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PITTSBURGH (AP) — Investigators looking into the collapse of a Pittsburgh bridge nearly one year ago are looking closely at damage to the legs of the structure, the National Transportation Safety Board said Thursday.

An agency update on the Jan, 28, 2022, 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 (30 meters) 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.

The update 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.”