Toward a circular infrastructure

Great strides are being made towards a circular economy. The Closing The Loop consortium, consisting of Nebest, Antea Group, GBN Group and Strukton Civiel, is taking the next step towards a circular and climate-neutral infrastructure in 2030 in response to the Circular Viaducts SBIR call. Parallel to this call, four graduating students from the Avans University of Applied Sciences were given the opportunity at Nebest to go through a similar process. And with success. The fresh perspective of the younger generation led to useful insights even within the experienced consortium.

Rijkswaterstaat wants to be at the forefront of the transition and work circularly as early as 2030. "In that capacity, the first circular viaduct in Kampen was built earlier," says Wouter van den Berg, New Business Manager at Nebest. "There 'people' thought quite a bit about that. It was modular rather than circular. Anyway, at least it started a positive movement. For example, an Open Learning Environment was created with different theme lines to engage in dialogue about the challenges and obstacles to achieving a circular acreage. That was the basis for the Circular Viaducts SBIR call, a call to the market to come up with physically applicable and procurement-ready circular viaduct concepts based on product innovations."

Almost simultaneously with the Circular Viaducts SBIR call issued by Rijkswaterstaat, four enthusiastic graduate students came our way, says Van den Berg. "A great opportunity for us and for them to participate in this project, parallel to the initial call, so they had the chance to take their own direction, but their findings could be included within the bigger picture. So we largely replicated the competition in which we participated as a consortium. The students went into pairs and were asked to develop their own concept for a circular viaduct, specifically focused on reuse. In doing so, they first used live sessions with municipalities and provinces, among others, to "hunt" for works of art that are nominated for unsustainable demolition within ten years. On this basis, an inventory was made of which materials will be available on the market when. Input that was obviously also perfectly usable to support the consortium's feasibility study."

After the joint inventory round, the students set to work to develop a design of a circular viaduct with released materials at a specific location. Important criteria included technical feasibility, economic perspective and environmental impact.

"Our research showed that more than 75% of the artworks are scrapped before the end of their technical lifespan, mainly for functional reasons, while the parts can still last a hundred years perfectly well," says Xander ter Meulen, who formed a duo with Marck Span. Based on the materials from an existing work of art in Groningen, which is about to be demolished, they created a design for a completely new viaduct in Nuth. "Despite the distance - all usable parts have to be transported from Groningen to Limburg - we achieved a reduction of 40% both on MKI and CO2 emissions. So building with used materials makes perfect sense," concludes Marck Span.

The other duo, formed by Steven Keemers and Twan Looije, followed a similar path, but in addition to researching profitability, described the process of how municipalities and counties could get started with reuse.

"We captured that in a clear roadmap," says Twan. "Our case study focused on the replacement of an overpass over the A44 Lisserweg. In our view, the first concept was too long and should have been twice as wide. We reduced the span from 40 meters to 28 meters with a width of 32 meters. To do this we used materials from an existing viaduct over the A9 motorway that was to be demolished just 30 kilometers away. All these efforts demonstrably lead to a reduction of 60% on the MKI, a 61% lower CO2 emissions and a cost saving of 60%. With that, we have also tackled the rationale that sustainable construction costs a lot of money."

Steven adds: "One thing we have learned from this research is that, above all, you have to think big and not let things initially seem impossible get in the way."

The design of both student duos was tested by a committee of as many as 30 parties against the previously set criteria during a live session in the Nebest Studio. "Moreover, the recommendations during the live session brought a lot in the refinement of both studies towards the defense," said Van den Berg. "Both duos ended up scoring wonderful grades of 8.3 and 9. Meanwhile, Xander is working at Nebest, Marck is also active in the field, and Twan and Steven have started advanced studies. In addition, as the Closing The Loop consortium, we were selected from no less than 32 submissions to realize the first circular viaduct with high-quality reused object parts in the Netherlands. Both graduation studies proved to be very valuable in this. I am convinced that without the young generation we will never achieve the goal of a circular economy/infrastructure. Because: the older, the more colored. The combination of experienced structural engineers with the fresh eyes of students leads to beautiful insights."

The students also look back enthusiastically. "We made a graduation attempt before this at another company, but that came to nothing," says Xander. "The guidance and benevolence of the people at Nebest was so obviously different. They themselves were super enthusiastic, incredibly helpful and that also motivated us tremendously to put in an extra load of hours to achieve a great result. It really was a top experience with the live session at Studio Nebest as the icing on the cake."