You probably could make a 3rd printer capable of printing the steel components for a bridge. If you pour enough money and time down the drain, there's no reason why you couldn't have some robots handling the scaffolding and "3D printing" the concrete too. It would be severalÂą orders of magnitude slower and more expensive than using the normal processes, but hey why build 10000 bridges when you can build just one that tech bros can masturbate to.
Âą this "several" is breaking the world record of heavy lifting
I really doubt that 3D printed steel will be able to handle to stress of a bridge support. Maybe it can be used for uniquely shaped joining panels, but recombined powdered steel is nowhere near as strong ir durable as cold rolled or forged steel beams.
A 12m stainless steel pedestrian bridge that took 6 years to make and was subsequently “strengthened” to meet safety requirements. Not quite the same thing.
second day you say? why, by then we can have the second backup bridge designed, printed, and installed next to the first, so that is not a problem. every two days, a new bridge.