If you walk along the Oudezijds Achterburgwal canal in Amsterdam, you will notice an elegant and aesthetically pleasing steel bridge for pedestrians. If not for the media attention it got, you would even consider it a regular feature of the city's architecture. But this bridge loaded with sensors, is actually the world's first 3D-printed steel bridge, according to an Imperial College London press release.

Printed by four robots in a matter of just six months, the bridge heralds a new beginning in additive manufacturing. Most 3D printing projects, whether they are designed for outer space or rapid infrastructure, use proprietary inks or starting material. This bridge, however, uses steel, a tried and tested construction material, and is actually an experiment to test whether it can find applications in 3D printing.

"A 3D-printed metal structure large and strong enough to handle pedestrian traffic has never been constructed before," said Imperial co-contributor Prof. Leroy Gardner of the Department of Civil and Environmental Engineering, in a press release. "We have tested and simulated the structure and its components throughout the printing process and upon its completion, and it’s fantastic to see it finally open to the public."