PITTSBURGH — The Pennsylvania Department of Transportation will conduct field assessments of five bridges, including one in Philadelphia, with structures similar to the Fern Hollow Bridge that collapsed on Friday.
“We are evaluating the condition of each of the bridges that have a similar structure,” PennDot spokesperson Alexis Campbell said in an email. “Based on initial assessment, all other bridges are in fair or better condition and are currently capable of carrying legal loads (i.e. do not require posting for weight restrictions) PennDot will also perform field validations of these structures.
The bridges have what is called “K-frame” construction, a design where the weight is placed on single supports that have no secondary support. The superstructure and deck of the Fern Hollow Bridge were rated in poor condition with ratings of 4 out of 9 and the substructure was rated 6.
Two bridges rated in fair condition are the Philip J. Fahy Memorial Bridge in Bethlehem and the McCallum Street Bridge, which spans Cresheim Creek between Chestnut Hill and West Mount Airy. The only steel-framed bridge in Wissahickon Valley Park, it opened in 1985 to replace a span dating from around 1891. The McCallum Street Bridge features rusted and weathered steel and a deck that rises 100 feet above the creek bed.
One of the other five bridges is in the Squirrel Hill section of Pittsburgh. This structure has a fair rating with scores of 7 on the deck and superstructure and 6 on the substructure.
The other two bridges are in the Pittsburgh area – the Canon-McMillan Alumni Bridge in North Strabane, which received a good rating with a 7 in all three categories, and the Shenango Road Bridge in Beaver, which is rated fair. with a 6 overall. categories.
The National Transportation Safety Board is investigating the cause of the Fern Hollow collapse, which injured 10 people.