[Zathras]

Interesting but I don’t think it will work.
Steel requires specific atomic structure of Iron, Carbon and other elements.
It also usually requires forging to place the stress patterns into the metal structure.

Kind of the difference between using stamped metal fork and a forged metal fork.
You can FEEL the difference in strength.

[LRoggy]

If it works just think how much of an uproar there would be from the Davis-Bacon supporters here!

[Still Thinking]

OK, so the foundation on one end is going to have to be strong enough to cantilever the bridge plus printer across the whole canal till it gets to the other end, or at least halfway, if they’re planning to build halfway across then build back to meet from the other side. That seems hugely wasteful. Second, what if you need cables? Cables do a great job for tension, and provide a little resiliency. even if a few strands break, the cable is still plenty strong to do what it needs to do. You obviously can’t print a good, resilient cable.

I’m tentatively calling BS.

[null and void]

3-D Printer Ping!

[Vince Ferrer]

It is an interesting attempt, but there are already better ideas of how to create large structures like this. MIT has been working on using small tinkertoy-like pieces made out of carbon fiber to assemble arbitrary large structures like bridges or skyscrapers:

A bridge made of this would be lighter and stronger than a bridge made out of current steel materials.

How to make big things out of small pieces

[USMCPOP]

Seems hugely wasteful compared to using hot rolled steel that has been made in an efficient mill. It’s hard to control the quality and properties of atomized metal (weld) under field conditions.

[tjps]

Its simple, just use Reardon steel.