Bus video gives more insight into Pittsburgh bridge collapse
HARRISBURG, Pa. – Video footage of a bus from the bridge collapse in Pittsburgh this year shows one end of the structure had already fallen when an expansion joint at the other end parted, federal investigators said Thursday.
The National Transportation Safety Board released an update on the Fern Hollow Bridge collapse, saying the video gives them more information about the sequence of events.
So far, there is no evidence of “widespread deficiencies” in the “types of rigid K-superstructures” that form the base structure of the bridge, according to the report.
The investigation update indicates that all aspects of the disaster are still under investigation and the cause has not yet been determined. Investigators plan mechanical and chemical tests on material samples and will examine the dimensions of the plates and the quality of the welds.
A preliminary report released less than two weeks after the January 28 collapse found that the collapse started at the western end of the structure and noted that there were no primary fractures in the beam sections. welded steels considered “fracture critical”. A critical fracture zone in a beam is the part most likely to show damage if the bridge suddenly failed.
When the Forbes Avenue Bridge gave way, it sent a city bus and four passenger cars about 100 feet (30 meters) into a ravine carved out by Fern Hollow Creek. Another vehicle exited the eastern abutment of the bridge and landed on its roof.
Although the preliminary report said a total of 10 occupants of the vehicle were injured, the agency has now concluded there were nine people in six vehicles. Two were seriously injured, two were slightly injured, four were uninjured and the status of one person’s injuries is uncertain, the agency said Thursday. No one was killed.
Natural gas lines broke and necessitated the evacuation of nearby homes.
The 447-foot-long (136-meter) bridge, around 50 years old, showed some deterioration during an inspection in September, but not enough to warrant its closure. The bridge has had a weight limit of 26 tonnes (24,000 kilograms) since 2014.
The future of the bridge is the topic of a virtual meeting Thursday night that city officials and neighbors are expected to attend.
The Pennsylvania Department of Transportation said up to $25.3 million in National Highway Performance Program funds would be used to rebuild the structure. The state agency released images of the “overall design concept” of the replacement bridge.
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