The Fern Hollow Bridge near Pittsburgh collapsed on Jan. 28, leaving 10 injured, at least four of whom required hospital treatment. Five vehicles and a municipal bus were on the bridge at the time of the collapse, and the cause of the tragedy remains unknown.
According to the U.S. Department of Transportation’s National Bridge Inventory, a September 2019 inspection of the Fern Hollow Bridge showed the deck and superstructure of the Fern Hollow Bridge were in “poor” condition. The deck refers to the surface or roadway of the bridge and the superstructure includes the aspects of the bridge that support the deck, such as beams and barriers.
The 50-year-old Fern Hollow Bridge was one of 3,198 in Pennsylvania designated by the Federal Highway Administration as being in “poor” condition. This designation signifies one or more of a bridge’s main structural components is deteriorated.
In the 2021 National Bridge Inventory, 39 bridges in Northampton County were classified as being in “poor” condition as well as 47 in Lehigh County. In total, 7.5 percent of the nation’s bridges are in “poor” condition.
Northampton County is above the national threshold since just 11 percent of its 356 bridges have “poor” ratings.
“It’s no secret that the nation’s bridges are in dire crisis,” said Dan Frangopol, Lehigh’s Fazlur R. Khan endowed chair of structural engineering and architecture.
However, officials from the Pennsylvania Department of Transportation have warned against using the Federal Highway Administration’s ratings as any indicator of bridge safety as there are only three designations: good, fair and poor.
David Petrik, an engineer in Allentown, said that typically bridges can be rated “poor” for three reasons: age, deterioration, or structural members.
“Bridges in Allentown have actually been pretty well rebuilt over the past 30 years,” Petrik said. “There’s only three bridges which are older than the 1950s, which is pretty significant. We have been fortunate to be in a well-established urban area with good representation to help us get funding to rebuild most of our bridges.”
The Route 378 Interchange is the closest bridge to Lehigh University with a “poor” rating. While the deck, which directly carries traffic, and superstructure, which supports it, both have conditions that qualify as “fair,” the overall supporting substructure condition is “poor.”
Chris Buck, ‘25, who lives in Lehigh County, regularly drives down this interchange. Buck was unaware there were “poor” quality bridges in the region.
“Now knowing that these bridges are rated negatively, I’d avoid them if possible,” Buck said. “I’m definitely less trusting of the bridges. That’s kind of freaky.”
Frangopol has worked with University of California-Los Angeles Professor Sriram Narasimhan to curate a series of research papers entitled “Bridge Asset Management Collection” for the American Society of Civil Engineers. In them, he said that an influx of federal funding is necessary to repair and rehabilitate the nation’s bridges.
According to WFMZ, Bethlehem owns 10 bridges that it says are inspected on a regular basis by the Pennsylvania Department of Transportation. The city of Allentown also utilizes PennDOT to survey its bridges.
“It is crucial to continue to follow national bridge inspection standards to ensure future bridges don’t collapse,” Petrik said. “Those inspection reports should then be reacted to with scheduled bridge rehabilitation and maintenance as necessary. They should not be taken lightly.”