Reinforced Plastic 3D Printed Footbridge by DSM and Royal HaskoningDHV to Be Installed 2020

DSM and engineering firm Royal HaskoningDHV will collaborate with the Dutch city of Rotterdam to build a 3D printed circular composite footbridge. I was initially extremely skeptical about fiber reinforced polymer (FRP) 3D printed bridges. FRP materials don’t have a very sustainable reputation, since they’re often quite difficult to recycle. Just the idea of a plastic bridge made me incredulous. After having seen a few parts of this bridge by DSM, however, I’ve begun to be more and more convinced that this is something useful and viable. What’s more, where 3D printed concrete has a lot of players in it now, 3D printed large scale construction in polymers is a relatively underexposed area.

Amid the cutting edge architecture of Rotterdam, the team wishes to place the footbridge in the park Kralingse Bos. The bridge will actually be co-developed with the City of Rotterdam and may even include sensors. These sensors would enable the monitoring of the real bridge in real-time to optimize maintenance, with the team hoping that it will represent an example of a Digital Twin solution.

Mozafar Said, Asset Manager from the City of Rotterdam, said of the project:

“The city of Rotterdam is proud to be a leader in the smart and circular use of composite bridges. Together with Royal HaskoningDHV and DSM, we are continuing to push the frontiers of sustainability for bridges, using thermoplastics which will enable greater circularity. The 3D printed FRP footbridge as a circular composite aligns with our city’s ambitious sustainability targets to reduce carbon footprint and promote liveability and we are proud to be the first city to test, print and install it.

“We see the use of composite bridges as a smart solution to replacing our older constructions. With more than 1000 bridges in Rotterdam, we are constantly looking to push the boundaries to develop the next generation of bridges which will be more sustainable and circular with lower maintenance and lifecycle costs.”

The bridge is made with Arnite, a family of PET and PBT mix materials for automotive and construction. The bridge will use virgin PET material, but it would be very tempting to, at one point in the future, connect this development with PET recycling of water bottles for example. Senior Application Development Specialist Additive Manufacturing at DSM, Patrick Duis, commented:

“The printed circular composite bridge enables the transition to a more sustainable and circular type of bridges with minimal wear and tear. Now that we have the new circular composite of recyclable source material along with the required performance properties available to us, we can start taking the environment-friendly design of the infrastructure to the next level.”

An image of an earlier Arnite bridge made by DSM, DHV and CEAD

Maurice Kardas, Business Development Manager at Royal HaskoningDHV, commented:

“We announced the prototype of this circular composite bridge in 2019 and with the vision and support of our partners DSM and the City of Rotterdam we can now take this one step further.

“Rotterdam and the Netherlands are ahead of the curve in innovation in infrastructure, particularly in the areas of sustainability and circularity. By introducing circular composites into their bridge infrastructure, Rotterdam proves once again to be a city ahead of the game. This is a step change which signifies a collective effort to bring innovation from idea to realization and ushers in a new era of sustainable design and bridge functionality.”

In the past, the team of DSM and Royal HaskoningDHV have worked together with CEAD, a Delft based large-format 3D printing company, to 3D print footbridges. Most probably they will continue to work similarly for the current project as well. Whereas 3D printing in concrete still seems like a far-off proposition, this is a near-term application that may very well be quite disruptive. By manufacturing bridges in factories, foot and bicycle bridges could be cost-effectively produced and shipped to a particular location. Especially given that these structures are light, entire bridges or large segments could be transported inexpensively to locations.

To me, this would be significantly more logical than printing in place. The bridge is often going to be lighter and less cumbersome than the printer from which it is made. More geometric freedom and the use of finite element analysis and other software can also lead to the construction of structures with optimized geometries that could go way beyond current designs.

By relying on a relatively long-lasting construction material that can be reused, lightweight 3D printed FRP bridges could be potentially circular construction elements. At end of life, these structures could be renewed or ground up to create new parts. Requiring less energy and material than steel and concrete bridges to manufacture, they could furthermore be more efficient to make, maintain, and build initially.

Then, looking past the initial life of the bridge toward the longer-term maintenance and replacing of bridges, the idea would be to have a more efficient solution for decades to come. Rather than crush up and waste concrete, complete recycling could mean that there will be significant lower environmental costs to replacing these bridges. Rather than looking at a bridge as a single architectural element, this project looks at them as cascading, temporary solutions that, throughout time, serially provide a solution to letting people cross rivers and streams. All bridges could, therefore, be part of an integrated management and recycling system that can take into account the CO2, material, energy, and waste used throughout time. To be very trendy, we could see this as the dawn of Construction-as-a-Service.

If the FRP bridges hold up to the rigors of the environment and day-to-day use, then we could indeed see a rapid introduction of this technology worldwide. It will take time to analyze the data and conduct tests, but once this is performed many bridges could be made in a very industrial fashion. A lot of construction relies on formwork or installations that are very customized labor-intensive processes. Silly articles always proclaim that somehow 3D printing solves all of this and would eliminate labor. For most additive construction projects, there would still have to be a lot of on-site labor and supervision—aside from the manual operations that you’d have to conduct with the printing itself. But, with 3D printing FRP bridges, we could actual see a lot of cost savings, if these structures are made serially or in a mass-customized manner through highly automated 3D printers in a factory. Slowly, but surely, I’m starting to see a future for 3D printing in construction.