Panther Hollow Bridge needs repairs to ‘critical’ support plates, work could take ‘less than a year’

It’s taken nearly six months, but Pittsburgh officials and consultants have determined that the Panther Hollow Bridge in Schenley Park likely will be closed through the summer and perhaps as long as another year for repairs.

The bridge was abruptly closed Oct. 19 out of “an abundance of caution” when inspectors for the city discovered problems with steel trusses that support the structure. The closure has created traffic problems in the area because the nearby Charles Anderson Bridge is closed for rehabilitation.

In a news release Wednesday, the city said consultants used ropes to rappel down the side of supports and other elements of the bridge for a hands-on inspection of its condition. After a full inspection that included a 3D structural analysis of the truss system, the city and engineering consultants are designing repairs and hope to go out for bids in June.

Asked in an interview how long the bridge might remain closed, Jacob Williams, a spokesman for the Department of Mobility and Infrastructure, said, “We’re hoping for less than a year because it wasn’t as serious as we expected.”

The closure of the two bridges in the park has created traffic problems in Squirrel Hill, which motorists use as an alternative to the park. Councilwoman Barb Warwick, whose district includes the park, declined comment Wednesday because she hadn’t talked with city officials about work needed on Panther Hollow.

Williams said the bridge needs repairs to its pins and gusset plates. In truss bridges such as Panther Hollow, gusset plates are considered critical members that are welded, riveted or bolted at seams where beams or other components come together to provide additional strength and distribute weight.

Pins are essentially longer bolts used to hold elements together.

Deteriorated gusset plates played a key role in the 2007 collapse of the Interstate 35 truss bridge in Minneapolis, according to investigators from the National Transportation Safety Board and Federal Highway Administration. After that incident, which killed 13 people, federal officials adopted minimum standards for the design of the plates and made them a critical element to review in bridge inspections.

The city announced the emergency closure in October, one day after a consultant unexpectedly found serious problems with steel truss supports during a routine load bearing evaluation on the 620-foot bridge. Before the exam, the bridge had a fair rating of 5, had no load restrictions and hadn’t been considered among the city’s many bridges with serious problems.

The bridge was built in 1897 and is “a very old and large example of steel arch technology and is also a rare example of a three-hinged deck arch. Just as noteworthy are the bridge’s stone arch approach spans,” according to historicbridges.com. It is nearly identical to the nearby Schenley Bridge except that Panther Hollow has large bronze panthers decorating each corner.

The website says the bridge should be considered “among the greatest of Pittsburgh’s treasures” because of its design and location in a city park.

In the city’s news release about bridge conditions, it also noted it has decided to raze the Wilkesboro Avenue pedestrian bridge that connected Brighton Heights and California before it was closed due to deterioration in 2007. Williams said there is little interest in refurbishing the bridge and the city is seeking bids to demolish it “sooner rather than later.”