NTSB report: Pittsburgh's Fern Hollow Bridge collapse started on Squirrel Hill side

The collapse of Pittsburgh’s Fern Hollow Bridge likely started on the west, or Squirrel Hill, side of the span, according to a preliminary report from the National Transportation Safety Board released Monday.

The brief report notes only facts surrounding the collapse and the bridge itself. It does not draw any conclusions regarding the cause of the Jan. 28 collapse.

A Port Authority of Allegheny County bus and four passenger vehicles were on the Forbes Avenue bridge that connects Squirrel Hill to the East End when it collapsed around 6:40 a.m.

The report said “a fifth passenger vehicle drove off the east bridge abutment following the collapse and came to rest on its roof.”

Ten people were injured in the collapse. Officials have said none of the injuries appeared to be life-threatening.

The report speaks mainly to the structural components of the bridge, which was rated in poor condition by PennDOT.

“Just because they say ‘poor’ doesn’t mean there is something significantly wrong with that bridge that is putting (motorists) in jeopardy,” PennDOT Acting Deputy Secretary Melissa Batula said during a briefing Friday.

The NTSB report said that “although certain areas of the welded steel girders were identified as being fracture critical, no primary fractures were found in these areas.”

NTSB releases preliminary report on the January 28 collapse of Pittsburgh’s Fern Hollow Bridge: https://t.co/rMfD3bDyC6

(Photo: The collapsed Fern Hollow bridge, as viewed from the east approach, showing the transit bus and four of the five passenger vehicles.) pic.twitter.com/WAA1gLt5s5

— NTSB_Newsroom (@NTSB_Newsroom) February 7, 2022

The Port Authority bus that had been on the bridge when it collapsed had seven cameras on it, including two outside the bus. NTSB officials wrote that the footage has been recovered and so far appears to be “consistent with the initial assessment of the bridge components.”

A group of specialists will further analyze the video, the report said. It could take 12 to 18 months for the board to release its final report.

The bridge, which had a “K-frame” design, had a posted speed limit of 35 mph and load limit of 26 tons per vehicle.

Officials have said the new span will likely not be another K-frame design, with Batula noting that such designs have become expensive.

PennDOT District 11 Executive Cheryl Moon-Sirianni said getting the necessary materials for a bridge with a K-frame design would likely be a lengthy process.

She said the New Kensington-based Swank Construction and HDR Inc., headquartered in Omaha, Neb., are working parallel with the NTSB. The transportation board remains on site investigating as crews begin removing debris and demolishing the remaining structure.

“Designers are working on what design may fit, working with the contractor, calling suppliers, looking at what options there are to expedite the design and construction,” Moon-Sirianni said.

She said there is no time frame for completing the design or demolition.

Five other bridges across the state have the same design as Fern Hollow Bridge, all of which have been inspected since the collapse, said Mike Keiser, PennDOT’s acting deputy secretary for highway administration.

“These other five bridges are in a little bit better condition – most are fair or good, and none of them have postings or restrictions on them,” he said. “There are no concerns with those other bridges.”

Bridges in Pennsylvania are rated on a three-tier scale: good, fair and poor. In the 9-point scale, “good” scores range from 7 to 9, “fair” ranges from 5 to 6 and “poor” is 4 and below.

“If you’re getting to the lower end of that (poor) score, it could mean you have more serious deterioration going on,” Batula said.

She said bridges are inspected every two years, though bridges with posted weight limits and poorly rated ones are generally inspected at least once a year.

Batula stressed that the three-tier rating system is meant to provide a quick assessment of bridges for those deciding upon and planning infrastructure improvements.

“A bridge condition is just far too complex to be fully described with just three condition ratings,” she said.

Related:

• Pittsburgh police officers recount surreal moments after Fern Hollow Bridge collapse
• Emergency contract to allow for design work to begin on Fern Hollow Bridge replacement
• Biden visits site of bridge collapse