NTSB investigators at the site of the collapsed bridge in Pittsburgh, PA. (Source: James Anderson, NTSB)
WASHINGTON (May 5, 2022) — The National Transportation Safety Board published an investigative update Thursday for its ongoing investigation of the Jan. 28, 2022, collapse of the Fern Hollow Bridge in Pittsburgh, Pennsylvania. Since the collapse, NTSB investigators have recovered, documented and examined structural components of the bridge, analyzed available video and prepared to test multiple steel samples.
The Fern Hollow Bridge, which carried Forbes Avenue over the north side of Frick Park, experienced a structural failure with the 447-foot-long bridge falling approximately 100 feet into the park below. At the time of the collapse, nine occupants were in six vehicles, including a transit bus operated by the Port Authority of Allegheny County. Two of the vehicle occupants sustained serious injuries, two sustained minor injuries, four were uninjured and the injury status of one is unknown.
NTSB investigators and investigative party members reviewed video footage from the transit bus’s camera system that provides information on the sequence of the collapse. The forward-facing camera showed the bridge deck separating at the east expansion joint. The curbside camera showed that, at nearly the same time, the west end of the bridge had already fallen off the west abutment.
(Video frame from the forward-facing camera, showing the opening expansion joint.)
(Video frame from the rear-facing curbside camera, showing the west end of the bridge already fallen off the west abutment.)
The investigation has not found any evidence of widespread deficiencies with rigid K-frame superstructure types.
NTSB and Federal Highway Administration investigators plan to conduct both mechanical and chemical testing on material samples prepared from portions of each bridge leg, as well as several girder sections. Investigators also plan to examine the plate dimensions and weld quality.
All aspects of the collapse remain under investigation while the NTSB determines the probable cause, with the intent of issuing safety recommendations to prevent similar events.
The full investigative update is available online at ntsb.gov
To report an incident/accident or if you are a public safety agency, please call 1-844-373-9922 or 202-314-6290 to speak to a Watch Officer at the NTSB Response Operations Center (ROC) in Washington, DC (24/7).