Why the Fern Hollow Bridge Collapse Could Have Been Avoided

A new report shows corrosion and blocked drains were documented in inspections since 2005 and recommends more than 10,000 U.S. bridges be inspected for similar issues.
Bridge Collape Scene


Corrosion, holes and blocked drains were consistently reported on inspections of the Fern Hollow Bridge years before it collapsed in January 2022, according to an interim report issued Thursday by the National Transportation Safety Board.

The report also shows inspection notes regarding the uncoated weathering steel structure’s deficiencies — including from the last inspection in September 2021 — were not addressed to properly rehabilitate the City of Pittsburgh-owned span. 

The Fern Hollow Bridge collapsed just after 6:30 a.m. on Jan. 28, 2022, taking a PAT bus and four passenger vehicles 100 feet into the Frick Park ravine below, injuring 10 people. A fifth passenger vehicle was also involved. The bridge has since been rebuilt and was reopened to traffic in December. 

The NTSB has been investigating the collapse for more than a year and says it will release its final report with further guidelines in the coming months.

It recommends more than 10,000 bridges across the U.S. that were constructed with uncoated weathering steel be inspected for similar issues. A Pennsylvania Department of Transportation spokesman did not return a request for a list of other Allegheny County bridges constructed with the same material.

“The NTSB found extensive corrosion damage and deterioration of the Fern Hollow Bridge legs during the on-scene examination of the collapsed bridge,” the report reads. “We also reviewed the National Bridge Inspection Standards inspection reports for the 17 years before the collapse. Starting in 2005, each of these inspection reports documented corrosion damage and deterioration of the bridge legs, including the most recent inspection report in September 2021, four months before the collapse.”

Maintenance recommendations were included in the yearly inspection reports for the Fern Hollow Bridge but were not performed during the 11 years leading up to the bridge collapse, the report continues. 

The report also notes the blocked drains led to corrosion of the structure.

“Uncoated weathering steel requires periods of dryness to form a protective oxide coating, or patina, that resists corrosion over time,” an NTSB press release reads. “Debris, dirt, and leaves were blocking the drainage systems on the Fern Hollow Bridge, allowing water to drain onto areas not intended for water flow and preventing the protective patina from forming.”

NTSB investigators found other Pennsylvania bridges have similar issues with drainage, debris accumulation and corrosion.

PennDOT spokeswoman Alexis Campbell told The Associated Press the agency will continue to cooperate with the investigation and that safe, reliable infrastructure is a top priority of Gov. Josh Shapiro’s administration.

In December 2022, Pittsburgh Mayor Ed Gainey’s office issued a report indicating 27 of the 147 city-owned and maintained bridges were in need of critical attention and another 69 had high priority issues. None of the bridges that were named in the report had been scheduled for repairs this year. 

The city has declined to comment on the report since it is part of the investigation.

Attorney Jason Matzus, who is representing a Squirrel Hill dentist who was severely injured in the collapse, told the Tribune-Review: “Hopefully, the NTSB recommendation will underscore the importance of bridge inspections and bridge maintenance and prompt bridge owners, like the City of Pittsburgh, to do their job and fix problems rather than ignore them once problems are discovered.”

Categories: The 412