'Cascade of failures': NTSB blames Fern Hollow Bridge collapse on city, state, feds

The National Transportation Safety Board on Wednesday spread the blame for the Fern Hollow Bridge collapse, strongly condemning the city of Pittsburgh for years of chronic inaction by idly allowing severe corrosion and decay to weaken the span and faulting state and federal regulators for their lack of diligent oversight.

The failures were avoidable, the safety board said. But, in hindsight, the result — a dramatic collapse, severely injured motorists, and a citywide panic about the safety of its bridges — was all but inevitable.

“This bridge did not collapse by an act of God. It collapsed because of a lack of maintenance and repair. It is just sad for the city,” board member Michael Graham said.

The bridge’s condition was so dire at the time it fell Jan. 28, 2022, investigators said, that it should not have been open to traffic.

During a 3¹⁄₂-hour virtual meeting, the board voted unanimously to accept investigators’ findings that pinned the blame for the shocking collapse on the failure of a bridge component called a transverse tie plate, part of one of the legs.

But, they said, the probable cause and origins of the catastrophe were more broad and deep than the breakdown of a single piece of metal.

They traced the disaster to Pittsburgh’s failure to address inspectors’ “repeated” maintenance and repair recommendations. Investigators criticized the “poor quality” of inspections and noted flaws in identifying which bridge components could have brought the span down if they failed.

And they found fault with calculations for how much weight the bridge could hold.

“The ultimate responsibility for safety of this bridge is on the City of Pittsburgh, solely on the City of Pittsburgh. They own the bridge,” NTSB Chairwoman Jennifer Homendy said after the hearing.

Photographs attached to inspection reports year after year, she said, showed “progressive deterioration … to the point of absolute destruction.”

“The information was there. They had it,” she said. “They didn’t use it. They didn’t follow up and invest the money and resources into making the repairs that were called for.”

Safety board investigators also found insufficient oversight by the Pennsylvania Department of Transportation and the Federal Highway Administration to ensure the bridge inspection program was carried out effectively, that repairs were made and load ratings were accurate.

“It really was a cascade of failures from the local government to the state to the Federal Highway Administration,” Homendy said.

Citing severe corrosion and structural deficits, Homendy said the bridge should have been shut down at the time it broke apart.

“The Fern Hollow Bridge collapsed from extensive corrosion and section loss damage due to repeated failures to act on known maintenance and repair recommendations that were documented in inspection reports from 2005 to 2021,” Homendy said.

“In fact, had contractors for the City of Pittsburgh correctly calculated and accounted for the effects of section loss and other factors back in 2014, the Fern Hollow Bridge would have, should have been closed.”

Wake-up call

The 447-foot-long Fern Hollow Bridge, which was built in 1970 and connected Regent Square and Squirrel Hill, collapsed into a Frick Park ravine about 6:40 a.m. Five vehicles, including a Pittsburgh Regional Transit articulated bus, fell about 100 feet into the gorge below.

Nine people were inside the vehicles. None died.

In her opening statement, Homendy apologized to them.

“On behalf of the NTSB, we are so sorry you experienced such a terrifying event,” she said. “The Fern Hollow Bridge collapse should never have happened.”

For the hearing, Homendy and Graham were joined by fellow board member Tom Chapman in voting to adopt investigators’ findings. The five-member board has two vacancies.

Before the board adjourned, Homendy noted the good fortune that inclement weather had delayed the start of school that morning.

“Had it not been snowing, there would have been school buses full of kids and countless commuters walking, biking or rolling across the bridge on the morning of the collapse,” Homendy said. “It is clear that the Fern Hollow catastrophe was a serious wakeup call for both the City of Pittsburgh and PennDOT.”

Year after year, according to the investigation, Pittsburgh failed to heed inspection reports that showed blatant evidence of corrosion and section loss.

“Everybody wants to build, and nobody wants to do maintenance,” Homendy said. “I hope our investigation changes some minds about that. We cannot take infrastructure for granted. Lives depend on it.”

As the bridge continued to decay, the board said, officials should have lowered the span’s load rating — which governs the weight of vehicles allowed on the bridge — after initially reducing it in 2014 to 26 tons.

“The City of Pittsburgh was responsible for inspecting and maintaining the Fern Hollow Bridge,” said Dan Walsh, senior structural engineer for the safety board’s Office of Highway Safety.

“Similar maintenance and repair recommendations were made in the inspection reports for more than 15 years leading up to the collapse. The city failed to act on them, resulting in progressive corrosion to the point of failure,” Walsh said.

Turning a ‘blind eye’

Among those watching the proceedings were lawyers for people injured in the collapse. Most of them have sued Pittsburgh and several engineering firms involved in Fern Hollow Bridge inspections.

“That bridge, literally, rotted out from under itself over a period of 16 years, and the city did nothing but turn a blind eye to it until it collapsed,” said one of those lawyers, Jason Matzus. He is representing Clinton Runco, a dentist who was hurt when he drove off the embankment while on his way to work.

Mayor Ed Gainey said Wednesday he couldn’t “get into the report right now” because he first wants to go over it “with a fine-tooth comb.”

He added his administration “inherited a lot” from his predecessors, but he did not point fingers at anyone in particular.

Dennis Collins, the safety board’s lead investigator, said that attempts by NTSB officials to understand the rationale for the lack of maintenance by the previous administration were unsuccessful.

“The quality of the record keeping … was low, and the high staff turnover in the department as a whole really prevented us from getting any sort of answer,” Collins said.

Since it launched its investigation, the board has released nearly 6,000 pages of documents in the case. It focused on the bridge’s corroded legs, clogged drains and the uncoated weathering steel alloy from which it was built.

Early in the hearing, the board played an animation detailing the collapse, featuring video from cameras on a Pittsburgh Regional Transit bus that went down with the bridge.

The animation included images of the collapse’s aftermath, photos of holes in the span taken during inspections over several years before the bridge fell and video footage of the span’s collapse. The visuals included graphics showing how elements of the bridge failed.

In that animation, investigators said they found that the bridge drains were clogged and not regularly cleaned out.

“Despite maintenance recommendations being repeatedly issued to the City of Pittsburgh, nearly every routine inspection found the drains on the deck to be partially or fully clogged,” said Steve Prouty, a structural engineer with the Office of Highway Safety.

“Staff found that multiple inspectors failed to perform the inspections in compliance with the National Bridge Inspection standards.”

The clogged drains led to the bridge legs not being able to dry, prohibiting a protective patina from forming on the uncoated weathering steel.

That, investigators said, led to section loss — or reduction of thickness — and thinning structural elements with extensive corrosion on all four legs.

Further, cross bracing that was supposed to be replaced never was, and a rust-inhibiting coating was never applied.

“Maintenance and repair recommendations were repeatedly made to the City of Pittsburgh, however they failed to act on them,” Prouty said. “This led to progressive deterioration and structural failure of the bridge.”

The fixes inspectors had suggested before the Fern Hollow Bridge fell, such as cleaning clogged drains, wouldn’t have been difficult to implement, said Hota GangaRao, an engineering professor at West Virginia University.

“It’s not expensive,” he said. “It’s not a technically difficult task.”

There was simply no enforcement to ensure it got done, GangaRao said.

Prouty said multiple inspectors failed to perform their work in compliance with the National Bridge Inspection standards.

“These failures contributed to the inability of the bridge to maintain its rated capacity,” he said.

During questioning, Graham focused on the more intense, hands-on inspections of the bridge’s so-called “fracture critical members,” defined as steel bridge components whose failure could cause a partial or full bridge collapse.

“Of all those different inspectors over that time from 2005, none of them were able to identify the legs as fracture-critical members?” Graham asked.

“None of them did,” Prouty responded.

“None of them did,” Graham responded. “Wow. That is just amazing.”

Load rating woes

Another key problem identified by the safety board investigators was the failure to recalculate the bridge’s load rating.

Walsh, the safety board engineer, said inspectors did not calculate an adequate load rating, especially in their failure to accurately measure and account for the weight and thickness of the asphalt paving on the bridge.

While the load rating for Fern Hollow Bridge was reduced to 26 tons in 2014, even that was not adequate, Walsh said. Had the bridge load rating calculations been performed correctly, it would have been reduced to less than 3 tons and required closure.

The bridge design called for the asphalt driving surface to be 3 inches thick. However, at the time of collapse, it was 6 inches, he said.

That, Walsh said, should have resulted in a lower load rating because of the increased weight of the asphalt. The bridge’s capacity also was overestimated because of a failure to recognize section loss in its legs, he continued.

“Had the correct calculations and assumptions been used, the bridge would have been closed,” Walsh said.

He also was critical of the city’s paving records, which, with the exception of 2017, did not document how much asphalt was removed and replaced.

Prouty said the bridge should not have collapsed.

“Had it been properly maintained and things had been repaired properly and rust had been prevented from getting worse, then it certainly would have been expected to last many more years,” he said.