Yeah.. "pedestrians will be able to walk across it" doesn't give me hope for a Sim City-esque BRIDGE GOES HERE and it's done in a month or two type future any time soon. Still cool though. There's a bridge here that's been being built for the last 6 years and all things considered it's a pretty puny bridge compared to the other ones (and no cars are allowed so it won't ease up traffic, unless it encourages more people to take public transportation but that's a different issue). Why they built it on-site is beyond me: in the past most bridges constructed in pieces somewhere else and then shipped in and put together where they want it to be, right?

Bridges that are designed for foot traffic only kinda scare me.. if I'm gonna be falling 3 feet into water or something that's cool but I've been over some that are hundreds of feet up. Just because it can support me doesn't mean that it didn't feel the pressure of much heavier people walking across it at various points.

Cool. Tech.

IZ, you build on site because it allows you do to more without having to deal with the bullshit of logistics. You bring in the materials and fabricate it there. It's why wind farms are somewhat locked into certain sizes inland. You need to make the pylons basically solid. To truck that in requires flat land, no bridges, gradual curves, that's not practical everywhere and is very limiting.

This is likely a proof of concept to see what we can do with this sort of technology in situ. Anything that gives freedom and breaks the current barriers in building technology is fantastic.

As for that bridge up hundreds of feet, everything is designed with a massive safety factor to it. It'll hold. If your bridge is stressed by a few fat people, you have other issues to worry about.

printed materials are generally weaker than their traditional counterparts.

metals moreso, as strengthening them requires precise thermal and compressive treatments to get high strength steel.