Brief history of: The Tacoma Narrows Bridge Collapse (1940)

today's video was suggested to me by Tim one of my patrons I can't thank you enough for your support on the 1st of July 1940 the world's third-largest suspension bridge was open to the public but within 3 months would be just a pile of twisted metal and concrete you might be thinking that it was some kind of espionage in the lead-up to the u.s. joining the second world war where if you did unfortunately you'd be wrong as the cause was a minor design flaw and an unfortunate gust of wind ok it wasn't as simple as that but lessons learnt would influence every large structure built afterwards ever since 1889 there has been a need for a connection between Tacoma and the Kitsap Peninsula in Washington State originally idea of a trestle bridge was floated by the Northern Pacific Railroad company but the plan didn't come to fruition and more serious plan was put forward in 1923 would the Chamber of Commerce attempting to find financing for the project joonie initial stages of gaining support the appointed Washington's state tolled Bridge Authority found that a crossing bridge would not be able to cover the costs of construction from collecting tolls alone once again the project looked like it could not go ahead however the nearby Puget Sound Naval Yard and Fort Lewis run by the Navy and Army respectively showed great interest in the crossing back body Armed Forces the toll authority requested 13 million from the federal government to design and build a crossing an engineer clock Eldridge was appointed to design a preliminary concept for a suspension bridge which would feature 7.6 meter deep trusses to stiffen the underside of the roadway however another engineer Leah Moises veteran at the Golden Gate Bridge project proposed a much cheaper and sleeker design Leon's idea would use much smaller Road trusses of only 2.4 meters this would reduce the cost of the bridge from around 11 million down to a much more affordable 8 million the strength of the cables was thought to be able to offset the wind pressure on the bridge and in doing so transfer distress to the anchor the bridge would have a span of 850 meters making it the third largest suspension bridge in the world even though the bridge was rather long it was only predicted have like traffic flow and due to mr. design only allowed for a 12 meter narrow two-lane roadway as well as being narrow the roadway was also very shallow due to the cheaper to construct two point four meter trusses it was these seemingly minor but visually appealing design decisions would cause problems for the bridges short life due to flexibility of the roadway as with most government dealings the cheaper bid got the contract but Public Works Administration approved six million for the construction project with the remaining balance of 8 million to be collected from tell crossings after completion were to go ahead given and moist F's design planned out construction works began on the 27th of September 1938 the construction project took 19 months and at a cost of 6.4 million dollars even as the project was being built stability issues due to the shallow roadway caused workers to dub the bridge galloping gertie as she swayed in even mild wind the bridge twisted opposite size of the center span as the overly flexible roadway danced in the wind even before opening day the bridge began to become infamous for its unwanted vertical movement on the 1st of July 1940 galloping gertie was open to the public as the first vehicles navigated the bridge noticeable bouncing could be seen quickly she became a tourist attraction as the public came to see the bridge bounce around as people timidly crossed the span due to the entertaining experience at the bridge many film cameras captured the new buildings bizarre behaviour several attempts to design out the unwanted movement were implemented by touching cables to the bridge attached to 50 ton concrete blocks however the cables to the blocks snapped soon after installation another set of cables were installed although this time they didn't snap but still proved ineffective the bridge also had hydraulic buffers installed when a towers meant the roadway but again these had little effect to the unwanted movement gathering winds from the southwest on the morning of the 7th of November 1940 started to create oscillations gradually the bridge flexed as it had done before as the winds reach 38 miles per hour at 7:30 a.m. but after each movement the roadway bubbled higher and higher up to heights of 5 feet as it caught in the wind Clark Eldridge one of the original British designers drove across the bridge at 8:30 on route to his office by 9:30 the winds hit 42 miles an hour and scientists professor FB Farquharson arrived at a bridge within two hours the bridge would be in ruins now mr. Farquharson is worth mentioning here as he had been employed to try and tackle the galloping gertie once and for all and he was only days away from fixing the bridge he was discovered during experiments in a wind tunnel but the weak roadway and poor aerodynamic properties were the cause of the oscillation Frederick farquharson proposed on the 2nd of November to fixes one would include cutting holes in the roadway girders to allow air to pass through eliminating the unwanted movement this was not favored by the toll bridge authority as it was permanent and a destructive fix as an alternative and less invasive fix farquharson proposed fitting fairings to decide at the bridge to help air flow around the roadway much like a wing but time had run out back to the faithful day and a profession with fixing a bridge could only stand by and watch as the structure swayed uncontrollably in the wind he set up a motion picture camera to capture the unfolding disaster for the next half an hour leading up to 10:00 a.m. the last few cars braved the bridge and paid their tolls two more vehicles would attempt to traverse the bridge a delivery van from the rapid transfer company and a car Niva would complete their journey but transfer van would be toppled over by the west tower with its driver and passenger escaping on foot the car driven by Leonard cotesworth a news editor for the Tacoma News Tribune and his daughter's dog tubby managed to get as far as the east tower when a jolt from the bridge flew the car into the curb cotesworth escaped and started crawling towards the east tower eventually he made it to the safety of the toll plaza and told her a member of staff about his dog and then contacted the office which in turn dispatched one of their photographer to capitalize on the unfolding disaster Eldridge arrived at the scene at 10:15 a.m. after receiving a phone call saying the bridge was about to go by 1030 parts of the bridge were starting to fall off some workmen managed to save the two from the topple van as the wind started to low one of the photographers from the News Tribune Hauer Clifford braved his way onto the bridge to try and rescued a dog tubby strand in the psittacosis car but he couldn't get close enough farquharson he was still taking photos decided to try to reach the car at 10:55 a.m. to rescued a dog he opened the doors to find a terrified tubby who then went to bite Farquharson finger unsuccessful he retreated back to safety at 10 a.m. larger and larger bits of concrete were launched into the air as the bridge ripped itself to pieces steel girders bent like rubber bolt shot off like bullets in all directions as suspension cables whipped around like a fishing line as the building tour itself to shreds hundreds gathers to watch the destruction firsthand at 11:02 the bridge finally gave out and a hundred and eighty-two meter stretch broke free falling into the puget below cables cracked through the air and sparks spat out from damaged electrical wiring farquharson on the east house scrambled for his life reaching the toll plaza as several sections plunged into the water boats were stranded car with tubby still inside disappeared into the Narrows and never to be seen again by 11:10 a.m. it was all over with the East and West house standing with only disfigured cables dangling along the once grand center span of the bridge in the aftermath an inquiry was set up to understand the cause of the collapse and to find who was at fault for such an embarrassing demise of a publicly funded project Eldridge was quick to point the finger at the moneylenders for using a cheaper design and pointed out four he had opposed Moises design due to the two point four meter girders acting like sails in the wind telling newspapers no man who held the purse strings were the whip crackers for the entire project we had a tried-and-true conventional bridge design we were told we couldn't have the necessary money without using plans furnished from an Eastern firm of engineers chosen by the moneylenders the Public Works Administration officials claimed that they had heard no such objections from the engineering team about the British design however barely two months have passed before one of the administration's own engineers David Glenn blew the whistle to say that he'd refused to approve the bridge in July 1940 Amos submitting a report rejecting the bridge for use citing fatal design flaws the PWA and the toll authority ignored the report and accepted the completed structure two weeks after Glenn came forward he was fired from the PWA the Federal Works Administration appointed a panel of free engineers to investigate the collapse no single person was blamed but instead highlighted free causes for the incident the first being the bridges flexibility due to the relatively small support girders the second issue was the roadway deck acting like an aerofoil causing lift and drag which was the reason for the twisting motion finally the engineer is lack of understanding of the potential aerodynamic capabilities of a bridge which could have been solved by Windtunnel testing of potential design chief designer Leah Moss F was let off the hook however his career was in tatters and the shambles of the Tacoma Narrows Bridge would shadow him for the rest of his life until his death in 1943 Eldridge was not so forgiving scolding myself for designing a bridge for no more than seven million in doing so undercutting the original more thicker girded expensive design soon after Eldridge would quit his job and start working for the US Navy on the island of Guam bizarrely he'll be captured by the Japanese during World War two and whilst in a powa AMP will be recognized by one of the Japanese officers who is studied in the u.s. who in turn approached Eldridge only to say Tacoma bridge controversially not all the money for the bridge could be recovered from the insurers straightaway as it was claims about the towers and cables could be reused and because of its the underwriters offered a meager 1.8 million unsurprisingly the state filed a dispute trying to recover at least 4.3 million dollars after a nine-month battle both sides agreed on a payout of four million this delay stopped any project for a replacement in its tracks as the u.s. entered the second world war a second bridge would be built after the war opening in 1950 and a closely resembled original design by Eldridge and Farquharson would play a part in the new bridges design with his testing of scale models in wind tunnels many lessons were learned from the first Tacoma Narrows Bridge collapse helping to improve design and construction of all suspension bridges built since and it was lucky to have only had a death toll of one poor old tubby the dog thank you so much for watching I hope you enjoyed the video thanks again for Tim for suggesting this subject please help the channel grow by liking commenting subscribing and also sharing also 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Channel: Plainly Difficult

Views: 229,569

Keywords: tacoma narrows bridge collapse, plainily difficult, 1940, us history, education, history guy, tacoma washington, bridge, faquharson, tacoma bridge collapse, building failure, zepherus, simple history

Id: fMsjyQHtmiU

Length: 12min 25sec (745 seconds)

Published: Sun Oct 14 2018