Large-scale 3D printing combined with digital design technology is permanently changing the shape of the built environment. Arup are leading the way with a first of its kind robot-printed steel bridge for Amsterdam. Set to be installed in the city’s Red Light District, the bridge is a 12-metre-long digital design masterpiece with curved, raw steel balustrades that belie its high-tech origins.

The award-winning bridge, developed by Dutch technology start-up MX3D, together with designers Joris Laarman Lab and a host of collaborators, offers a glimpse into how computational design working with state-of-the-art robotic welding technology could shape the cities of the future.

Digital design bringing form and function together

Fully 3D printed in stainless steel, the MX3D bridge is the culmination of a long-held dream to blend traditional steelwork and advanced digital modelling for an inspired, structurally sound piece of public urban infrastructure. Computational design and 3D printing worked together to streamline the design and production process, allowing designers to explore a greater freedom of form and greatly reduce delivery timelines.

With Arup as lead structural engineer, MX3D created intelligent software that transformed welding machines into 3-D printing robots capable of producing a fully functional steel bridge. Advanced parametric design modelling – a tool for designers to explore new shapes using code - enabled our engineers to significantly fast-track the initial design process. With the software capable of producing iterations in quick succession to reach an optimal design, the system offers the best solution against a set of benchmarks.

Departing from the traditional monolithic U-shape bridge concept, the team ran extensive iterations to progress swiftly through several stages of design. The final, more organic, S-shaped bridge marries structural integrity and functionality without compromising aesthetic relevance.

Designing by experimentation: digitally driven design process tests new boundaries 

Transcending its public function as a footbridge across the Oudezijds Achterburgwal canal, MX3D serves as a proof point for how digital design tools and 3D printing may forever alter the built environment. As an object for public use, Joris Laarman wanted MX3D to be a revolutionary piece of art that fully explored the rational design freedom allowed by 3D printing for large-scale infrastructure.

Parametric design modelling was a perfect fit for this boundary-pushing design process. The team worked with Grasshopper and Karamba, a tool for designers to explore new shapes using generative algorithms (graphical algorithm software) for 3D modelling tool Rhino to refine the design. The programme works by producing successive design iterations under a given set of parameters, moving from an initial test form towards the optimal or final shape.

Additional software can assign accurate material properties to the model, enabling extensive testing such as load path analysis even before the final bridge is built. The team ran digital simulations of the bridge, removing excess material by mixing structural calculations with geometric manipulation, teaching the algorithm to recognise which parts of the bridge are less crucial.

Designing beyond the codified materials was made possible thanks to repeated testing: Lab material test results, structural element tests results, and full-scale final test results would inform engineers working out the design. The testing sequence feeds into the structural assessment, allowing engineers to check the safety and serviceability of the bridge.

3D printing comes of age: printing large-scale urban objects

After arriving at a final design, the team moved into the production phase. Understanding materials performance was one of the first steps of the process: the material and mechanical properties of the self-supporting 3D printing steel differ from those of regular steel. To address this, the team ran several tests including load viability to ensure that the structural behaviour of the bridge complies with code safety requirements and confirms the performance of this new 3D printing steel.

3D printing, also known as additive manufacturing, is a novel method of manufacturing parts directly from a digital model by building layer after layer of a material. This new, high-precision technique provides opportunities and architectural freedom to designers and engineers alike, while potentially reducing the amount of material used and wasted. Printing began in March 2017 and the completed bridge was put on display at Dutch Design Week in October 2018. 

The design was by far one of the most challenging tasks of the MX3D bridge project. We chose to work with Arup, as their experience with innovative projects and generative design were crucial to the project. Our collaboration became even stronger than we expected. Now Arup plays a key role in the co-development of the design method for our metal 3D printing technique.

Gijs van der Velden


MX3d Bridge printing video still
Watch this video to see how the bridge came to life.

Digital Twin: data sensors to track performance

The bridge will be equipped with a sensor network to gather data which will be used to build a digital twin to monitor the health of the bridge. The digital twin will track performance under different environmental conditions and changing dynamic loads, including tracking pedestrian use, checking corrosion, or studying deflection and support forces, all of which will enable the further development of a data-centric design language. 

Collaborative partnership: key to innovation in the built environment

To bring the project to life, MX3D set up an innovative working collaboration with a large group of partners marrying expertise across disciplines, including software, hardware, construction and welding. These include Autodesk, ArcelorMittal, Arup, Force Technology, Imperial College London, Air Liquide, ABB Robotics, Heijmans, Lenovo and Lloyds Register Foundation.

Among the public partners are TU Delft, AMS Institute (Amsterdam Institute for Advanced Metropolitan Studies) and the Municipality of Amsterdam. On the sponsoring side are STV, Oerlikon, FARO and Plymovent, while the Visitor Centre is supported by the VSB Fund.