Well thats sorta accurate. It was the beams that are made with pre tensioned cables inside. The "camber" or "deflection rate" is calculated to specify the amount of pretension in the cables based on the dead load applied to the beams based on deck thickness and rebar weight.im no expert. dad and i talked about that exact bridge before he died.. they are pre arched and the weight of the loaded concrete them level or close too it. just like the old hump back semi flat beds that's why they are arched. dad had 60+ years exp in all aspects of const.
The consulting firm engineer screwed the pooch on this 1 calculation.
I didnt work in construction, I just designed and basically made the blueprint of how to design roadways. I didnt do bridgework but I did ask one of my friends at ODOT that did do bridge design, how this happened and that was the explanation I got from her.
And as you said, flatbed trailers that are cambered and designed to lay flat at maybe 60k pounds. (not sure of the number but thats close)