tmr i want go贵州瓮马铁路南北延伸线湘江特大桥的 opened day , but first i want ask , why so many steel? i see video of engineer do work , they use crane lift , it's too much strain on human body

, and what is meaning of "控制性工程"?
i heard say this bridge have very hard terrain , like canyons , but still they make it so long

, i want to see how they do it, maybe take a trip there

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and 723.3米 main span wow , that's like 2 skyscraper tall

, how they make it not fall down? i think need more information about bridge design
