World’s first 3D-printed pedestrian bridge pops up in Madrid

Alcobendas bridge, a 3D printed bridge in Spain.

Behold, the world's first 3D-printed pedestrian bridge. Inaugurated December 14 in the park of Castilla-La Mancha in Alcobendas, just south of Madrid in Spain, the micro-reinforced concrete structure spans nearly 40 feet in length and was created by fusing layers of sand using a massive d-shaped 3D printer.

It's the brainchild of the Institute of Advanced Architecture of Catalonia, a Barcelona-based research and education center that worked with a contingent of architects, mechanical and structural engineers, and municipal representatives to bring the design to life.

Besides Acciona, the firm that performed most of the heavy lifting, both literally and figuratively, the institute's most notable collaborator was Enrico Dini, the so-called "man who prints houses". Dini developed D-Shape, a massive 3D printer that's the first—and perhaps only—of its kind to fuse sand into layer after layer of solid rock. With the Alcobendas bridge marking a civil-engineering first, the IAAC is hailing the construction as a "milestone for the construction sector at international level."

But the designers didn't neglect to tip a hat to the ur-architect: nature. The IAAC leveraged parametric modeling to not only reflect the "complexities of nature’s forms" but also optimize the distribution of raw materials.

"The computational design also allows to maximize the structural performance, being able to dispose the material only where it is needed, with total freedom of forms, maintaining the porosity thanks to the application of generative algorithms and challenging the traditional techniques of construction," the institute said. The result? Less waste, greater stability, and one heck of a conversation piece.