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Fern Hollow Bridge
media credits (ID:427417)
NTSB Board Meeting - 2022 Fern Hollow Bridge Collapse : The National Transportation Safety Board held a virtual board meeting Feb. 21 to determine the probable cause of the collapse of the Forbes Avenue Bridge over Fern Hollow (also referred to as the Fern Hollow Bridge) in Pittsburgh, Pennsylvania. On Jan. 28, 2022, the 447-foot-long bridge experienced a structural failure and fell approximately 100 feet into the park below. Six vehicles were on or near the bridge when it collapsed and four people sustained injuries. Investigators found corrosion, deterioration, and section loss on all four of the bridge’s legs due to the continual accumulation of water and debris. This finding led the NTSB in May to issue an early safety recommendation urging the Federal Highway Administration to develop a risk-based, data-driven process to identify, prioritize, and perform any incomplete follow-up actions on bridges with uncoated weathering steel components. During the board meeting, the NTSB’s board voted on the final findings, probable cause, and recommendations. The board also voted on all changes to the draft final report. Additional information is included in the public docket for the investigation. The docket includes factual information, including reports, interview transcripts, and other investigative materials. https://www.ntsb.gov/news/events/Pages/HWY22MH003-BMG.aspx
media credits (ID:433703)
NTSB Animation – Overview of the collapse of the Fern Hollow Bridge : On Friday, January 28, 2022, about 6:37 a.m. eastern standard time, the Fern Hollow Bridge, which carried Forbes Avenue over the north side of Frick Park in Pittsburgh, Allegheny County, Pennsylvania, experienced a structural failure. As a result, the 447-foot-long bridge fell about 100 feet into the park below. The collapse began when the transverse tie plate on the southwest bridge leg failed due to extensive corrosion and section loss. The corrosion and section loss resulted from clogged drains that caused water to run down bridge legs and accumulate along with debris at the bottom of the legs, which prevented the development of a protective rust layer or patina. Although repeated maintenance and repair recommendations were documented in many inspection reports, the City of Pittsburgh failed to act on them, leading to the deterioration of the fracture-critical transverse tie plate and the structural failure of the bridge. At the time of the collapse, a 2013 New Flyer articulated transit bus, operated by the Port Authority of Allegheny County, and four passenger vehicles were on the bridge. A fifth passenger vehicle drove off the east bridge abutment after the collapse began and came to rest on its roof on the ground below. As a result of the collapse, the bus driver sustained minor injuries and two bus occupants were uninjured. Of the six passenger vehicle occupants, two sustained serious injuries, one sustained a minor injury, two were uninjured, and the injury status of one was unknown.
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NTSB investigators beneath the collapsed Fern Hollow Bridge
media credits (ID:427413)
NTSB investigator points out a detail on the buckled steel deck of the Fern Hollow Bridge
media credits (ID:427414)
NTSB investigators at the scene of the Fern Hollow Bridge collapse
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NTSB investigators at the scene of the Fern Hollow Bridge collapse
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Post-collapse scene at the Fern Hollow Bridge
media credits (ID:427419)

General Information

Other name(s): Forbes Avenue Bridge
Beginning of works: 1972
Completion: 1 June 1973
Status: collapsed (28 January 2022)

Project Type

Structure: Rigid frame bridge with inclined legs
Support conditions:
Function / usage: Road bridge
Material: Weathering steel bridge
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Awards and Distinctions

1974 award winner  

Location

Location: , , ,
Address: Forbes Avenue
Replaces: Fern Hollow Bridge (1901)
Replaced by: Fern Hollow Bridge (2023)
Coordinates: 40° 26' 22.31" N    79° 54' 1.08" W
Show coordinates on a map

Technical Information

Dimensions

total length 136.2 m
number of spans 3
abutments number 2

Cost

cost of construction United States dollar 1 230 000

Materials

piers weathering steel
girders weathering steel

Participants

Owner
Design
General contractor
Steel construction
Steel erection

Relevant Web Sites

  • About this
    data sheet
  • Structure-ID
    20087280
  • Published on:
    24/10/2023
  • Last updated on:
    26/10/2023
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