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  • These women are working on the Churchill  tank, a World War two era British tank  

  • that was heavily armored, but agile enough  to climb. From 1941 to 1945 thousands  

  • of what The New York Times called the  "world's deadliest tanks" were made

  • But there was a problem: the Churchill tank  weighed at least 40 tons, 36 metric tons.  

  • Imagine 20 cars. That would cause a normal bridge  

  • to buckle without a way to cross waterthe Churchill tank was basically useless

  • American tanks had the same problem. And as the  war waged on, the allies needed new bridges and  

  • replacement ones. Bombed out bridges like this one  in Germany needed a sturdier fix than a gangway.  

  • The solution to both of these problems was a new  type of bridge that improved on old breakthroughs  

  • and also represented a model maker's way of  thinking about how a bridge could win a war

  • Here's a bridge being built in China in 2020. Now  imagine no heavy machinery, no custom design, no  

  • materials heavier than a person could carry, and  no reliable access to the other side of the river.  

  • And half the time, you had to build it at night. That's the challenge of a wartime bridge.  

  • Donald Bailey was an engineer at the British  Experimental Bridging Establishment in 1940,  

  • and he needed a way to make  the standard temporary bridge,  

  • the Inglis bridge work for a new generation  of heavy tanks. When the Inglis bridge buckled  

  • under test weights, Bailey took an envelope  out and sketched an idea for a new bridge

  • He had made models since he was a kid and used  them to help test his design. He needed something  

  • adjustable to a range of gaps. It could  work with a pontoon floating in a river  

  • as well as with land. It had to be  made of something other than aluminum  

  • because airplanes needed that. It could be made  easily by manufacturers. No confusing parts,  

  • but most importantly, everything had to fit insmall service truck and be lifted by six soldiers

  • The design is strong and more flexible  than earlier ones like the Inglis Bridge  

  • or this small box girder bridge that  was also used. The panel was smaller  

  • than a box girder, lighter and easier to stack. This is the key to his design. I'll show you

  • It's the real breakthrough ingredient. This  reinforcement makes a bridge that's really strong,  

  • but at just five hundred and seventy pounds  or two hundred and fifty kilograms, six  

  • people could lift it. Other designs like the  Inglis bridge, twisted under heavy weight

  • The Bailey Bridge didn't. You can see how easy it is to move in  

  • this video made shortly after the war. Panels were  joined by pins driven in. After that, soldiers  

  • laid a transom across. I used glue to join  mine, but clamps made the process even easier

  • But it is the next stepbefore finishing the bridge,  

  • that made the Bailey Bridge even more special. See these men pushing? You could roll a Bailey  

  • Bridge across a gapimportant when you  couldn't get to the other side during a war

  • I can kind of show you with  mine and this roller right here

  • Rollers to slide the bridge alone and  a link to make the front of the bridge  

  • slightly tilt up by making the bottom longer than  the top. You can see it here in this Army manual

  • The bridge is pushed along the rollers with  more weight, usually more panels in the back  

  • to keep it from tipping over. Sometimes  they drive on it as a counterweight too.  

  • In the front, this link makes the nose tilt up. The snoot didn't droop

  • That helps keep it from sinking into  the gap as it gets pushed across

  • Adding a second or even third level was easythanks to the Bailey Bridge's modular design.  

  • These bridges quickly became an  indispensable tactical trend

  • By 1943, wartime manuals were  sandwiching crucial Bailey Bridge facts  

  • in between information about German  guns and warnings about dangerous fish

  • The Allies built twenty five hundred Bailey  Bridges in Italy and fifteen hundred in  

  • northwest Europe, as well as some in other  theaters, allowing those heavy Churchill tanks  

  • and the American equivalents to  move over land and water alike

  • General Dwight D. Eisenhower said,  "along with radar and the heavy bomber,  

  • it was one of the three most important engineering  and technological developments of World War II." 

  • Now, labeling the Bailey Bridge as  the reason the Allies won the war,  

  • it's impossible to say. However, a model maker's  breakthrough gave them a tool that was flexible,  

  • fast and strong in a war that  needed all three of those things

  • The modular design presaged a more  flexible, nimble type of construction

  • And the Bailey Bridge did allow them to cross the  rivers in Italy and push a bridge over the Rhine.  

  • They could use a Bailey Bridge, playing accordion  

  • over the water. And  

  • they could cross and play piano amidst the ruins.

These women are working on the Churchill  tank, a World War two era British tank  

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B1 Vox bailey war design churchill needed

The bridge design that helped win World War II

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    林宜悉 posted on 2021/03/12
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