NTSB Finds 'Immediate Implications For Bridge Safety Nationwide'

WASHINGTON, DC — The National Transportation Safety Board on Thursday recommended a national review of inspection reports for bridges made of uncoated weathering steel. The recommendation came amid the agency's ongoing investigation into the January 2022 collapse of the Fern Hollow Bridge in Pittsburgh.

The board also asked the Federal Highway Administration to develop a process for bridge owners nationwide to perform necessary follow-up actions recommended in the inspection reports on the 10,000 bridges nationwide made of such steel.

The city-owned Fern Hollow span collapsed into Frick Park on Jan. 28, 2022. Five vehicles and an articulating Pittsburgh Regional Transit were sent plummeting onto a park walking path. No one was killed in the incident, but 10 people were injured.

President Joe Biden, who was in town that day to tout the Bipartisan Infrastructure Law that had been recently passed, toured the site and made a return visit in October. The bridge replacement project was fast-tracked and a new Fern Hollow span opened in December.

While the Fern Hollow bridge investigation is not complete, the NTSB said in a release that it is making this early recommendation "due to the immediate implications for bridge safety nationwide." The final Fern Hollow report is expected to be issued within months.

NTSB investigators discovered corrosion, deterioration, holes and section loss on all four of the Fern Hollow Bridge’s legs due to the continual accumulation of water and debris.

According to the NTSB, uncoated weathering steel requires dry periods to form a protective oxide coating, or patina, that resists corrosion over time. 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.

Investigators found that prior inspections of the Fern Hollow Bridge performed on behalf of the Pennsylvania Department of Transportation identified drainage problems, but regular maintenance failed to occur.

NTSB investigators and engineers conducted limited inspections of some other similar steel-frame bridges in Pennsylvania that revealed maintenance issues similar to the one that helped to trigger the Fern Hollow collapse.

In a May 3 board report, three of the 10 spans were identified: the McCallum Street Bridge in Philadelphia, the Shenango Road Bridge in Darlington and the Fahy Bridge in Bethlehem.

The agency noted that if used under appropriate conditions and properly maintained, weathering steel bridges can last for decades.

"However, as with any other steel, failure to properly maintain uncoated weathering steel can lead to corrosion damage, deterioration, and section loss in critical components, thus reducing the safety and service life of the bridge," the report stated.