It sounds like the university is getting by on a technicality with its “first-ever” claims, but that doesn’t make this project any less interesting. Manufacturing of the concrete parts has begun, and it’s anticipated that bridge construction will start in September. To get to the point where the 3D printed parts were considered reliable, the team at the university first built a 1:2 scale model, which was able to hold a 2,000kg (over 4,400 pounds) load.
As for why this process is an improvement over standard concrete techniques, printing a bridge will use far less concrete than pouring it into molds. There’s an environmental impact here, as well — the production of concrete cement releases CO2, so cutting down on those emissions is worth noting. There’s also more freedom of design, as a 3D-printer can fabricate shapes that are much harder to produce with a mold.
Another benefit is that the steel reinforcement cables can be printed at the same time as the concrete parts, leading to pieces that are “pre-stressed” for additional stability. Of course, this bridge is meant for much lighter weights than those that handle auto traffic are meant for — it’s not clear that this production technique would be able to scale up to handle a more intense load. But even if 3D printing can only be used for less strenuous jobs, there’s still plenty of places where it could be useful.