PennDot will review Philly bridge, four others with similar design as the collapsed Pittsburgh bridge

PITTSBURGH — The Pennsylvania Department of Transportation will conduct field evaluations of five bridges, including one in Philadelphia, with structures similar to the Fern Hollow Bridge that collapsed Friday.

“We are evaluating the condition of each of the bridges which have a similar structure,” PennDot spokesperson Alexis Campbell said in an email. “Based on initial evaluation, all of the other bridges are in fair or better condition and are currently able to carry legal loads (i.e. do not require posting for weight restrictions). PennDot will be conducting field validations of these structures as well.

The bridges have what is called a “K-frame” construction, a design where weight is placed on single supports that have no secondary backup. The superstructure and deck of the Fern Hollow Bridge were rated in poor condition with scores of 4 out of 9 and the substructure was rated a 6.

Two bridges rated in fair condition are the Philip J. Fahy Memorial Bridge in Bethlehem and the McCallum Street Bridge, which spans the Cresheim Creek between Chestnut Hill and West Mount Airy. The only steel-frame bridge in Wissahickon Valley Park, it opened in 1985 to replace a circa-1891 span. The McCallum Street Bridge features rusted weathered steel and a deck that soars 100 feet over the creek bed.

One of the other five bridges is in Pittsburgh’s Squirrel Hill section. That structure has a fair rating with scores of 7 on the deck and superstructure and 6 on the substructure.

The two other 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 in all categories.

The National Transportation Safety Board is investigating the cause of the Fern Hollow collapse, which injured 10 people.