 It's December 21st 2022, and a new bridge is being opened for vehicular traffic. This event marks the third bridge on this site. Usually a new bridge is due to the old one being put out to pasture, as it's gotten a little bit too expensive or complicated to maintain. However, this time the previous bridge kind of forced the requirement of a new one by refusing to stay uncollapsed. Interestingly, the previous bridge only fell apart 11 months before, marking a pretty impressive rebuild time. This video is a bit of a rare one for me, as no one thankfully died. A feat of brilliant luck when you look at this picture of the bridge post self dismantling. Well, although disaster came in 2022, our story will start just over 50 years before in the magical period known as the 1970s. Background This point on the map has been a location of a bridge dating all the way back to 1901. It carries the Forbes Avenue across Frink Park in Pittsburgh, Pennsylvania. The road allows a quicker cut through for traffic, heading towards and away from Pittsburgh. By the 1970s, the original steel deck arch was getting a bit long in the tooth, and at an age of over 70 years, it needed replacement. This would come along in 1972 when the original Fern Hollow bridge closed to traffic and a new one started construction. The new crossing was penned by Richardson, Gordon and Associates Design Firm. It had a four-lane undivided roadway, which was two lanes in each direction. The main structure had two steel girders running in parallel each side of the bridge, held together with a K-frame. Running along the bridge under the roadway was rolled steel stringers. At each end of the bridge, concrete caps were placed on masonry abutments, in which the steel structure was placed. The steel structure was then supported by steel beams with x-bracing sighted on reinforced concrete. The steel used wasn't planned to be painted over. Well, that's madness. What about rust you may be screaming at the screen? But there was a neat feature of the particular steel employed on this bridge. The bridge was built with a thing called weathering steel. It was a particular alloy formulation that would in theory not corrode, instead forming a layer of protecting rust on its surface. It wasn't perfect though, as it wasn't impervious to rust from standing water, as such proper drainage is required. On top of that, welds can be weak points in a structure like this, and as such they need to weather at the same rate as the steel. If not, then failure can occur. The 447 foot long bridge opened on 1st June 1973, and just the next year, it won an award from the American Institute of Steel Construction in 1974. The bridge had a speed limit of 35mph for vehicles, and a maximum posted vehicle weight of 26 short terms. As the years went on, the weathered steel would prove to be not completely safe, as corrosion beyond the surface level patina started to set in. As early as 2005, corrosion and deterioration was seen in the bridge's legs, causing concern with inspectors. Block drains were allowing debris to form over the vital steel sections. In order for the weathered steel to work, it needs to form the patina during dry periods. This can be hindered by material sitting in drainage areas, keeping the steel damp. You see parts of the bridge were rusting, so much so that in 2009, the city installed steel cables to laterally support the bridge on its legs, to help the original and rusting cross bracing. Over the coming years, the bridge would continue to be inspected, and issues would continue to be noted. Each inspection came with recommendations, but were not performed by the city. In 2014, the cables were retitoned, and in 2018, one of the rusted cross beams was photographed by a local resident. The issue was reported and the beam was removed, leaving just the cables in place. The bridge was again inspected in 2021, and yet again issues were highlighted. But soon enough, disaster would strike the Fern Hollow Bridge. The Disaster It's the snowy morning of 28th January 2022, and a port authority bastard approaching the Fern Hollow Bridge. Overnight snowfall had covered the bridge's structure. It's heading eastbound, and as it drives across the bridge, it's bouncing and shaking along the roadway. The time is roughly 6.35 in the morning, and the western part of the bridge is seen on the bus's rear-facing camera to have fallen off of its abutment. At around the same time, the eastern end's expansion joint had opened, as also seen on another camera on the bus. Residents around the same time heard loud banging and whooshing sounds emitting from the area of the bridge. Shortly after, the structure plunged 100 feet down into the ravine. Five vehicles were on the bridge at the time, and in a case of terrible luck, another vehicle was approaching westbound. It flew off the abutment and landed on its roof. Amazingly, no one was killed in the collapse, although some were injured. Emergency calls came in, and first responders were dispatched. The first on the scene had to rappel down the hillside to reach the stranded victims. And a jogger, who was thankfully running by, managed to assist in rescuing people from their cars. A ladder was placed next to the bus, helping in evacuating its driver and the couple of passengers aboard. If the collapsed bridge wasn't enough, then a burst gas main would add salt into the wound. It had been damaged as it ran along the underside of the structure. This would require the evacuation of nearby residents until the gas line was shut off. Everyone was rescued by 8.30 in the morning, although the wreckage would still be searched for several hours more, but amazingly, no one else was found to be trapped. A crane was employed to remove the stricken vehicles, with the bus finally being lifted to safety on the 31st of January. Aftermath So, due to it being a road bridge, the NTSB would be in charge of the investigation. NTSB officials were dispatched and began pouring over the wreckage the same day. They discovered, via the bus's cameras, that the failure started on the western end of the bridge, but initial inspections of vital welding joints showed no fractures. What they did find, however, was a very rusty and poorly maintained structure. A preliminary report was posted in February 2022, but a full report has yet to be released. However, the NTSB did release some recommendations for other bridges of similar design and construction to be inspected as there was a high risk of a similar failure unfolding. Quickly the need for a new crossing led to the third bridge over Frink Park, which opened in December 2022. Now hopefully we'll find out more soon about the definitive cause of the disaster, but we will have to wait and see. But in the meantime, maybe check out one of my other videos of a bridge self-deconstructing itself. This is a plainly difficult video. All videos on the channel are creative commons at Tuition's share light licence. Plainly difficult videos are produced by me, John, in the currently warm but rainy corner of southern London UK. I have Instagram and a second YouTube channel, so check them out if you want to see other stuff that I make, and I'd like to thank my Patreon and YouTube members for your financial support. And all that's left to say is thank you for watching and Mr Music, play us out please.