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| Re: Debris falls from #7 train, again, and again (1515032) | |||
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Re: Debris falls from #7 train, again, and again |
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Posted by TransitChuckG on Thu Jun 6 14:15:30 2019, in response to Re: Debris falls from #7 train, again, and again, posted by Fisk Ave Jim on Wed Jun 5 13:51:28 2019. When you stop and think on how construction is done nowadays, back then building box girder elevated lines, which are essentially a series of bridges, all calculations & measurements with allowances for stress & seasonal expansion/contraction were figured out by men gifted with mathematical skills along with the worlds first analog computer...the slide rule. Truly amazing.Let us not forget #2 lead pencils & legal pads! I started drafting with pencils, etc. I watched the engineers calculate stress , strain, etc. with math skills and slide rules. I graduated to 2D- Auto-Cad, and finally 3-D Solid Works. Nowadays,computers figure out stress/strain ,etc., but you have to know what to input. |
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