The innovative Czech company So Concrete, which is successfully developing the field of robotic construction technologies, designed and realized the project of the unique Výstaviště tram stop in Holešovice, Prague. The construction of the stop uses the natural principles of internal force distribution or pressures and tensions in the structure, and the resulting design is not only unique, but above all maximally efficient. Compared to conventional technologies, this approach saves up to 60% of material, and in terms of economics and sustainability, robotic 3D printing of high-performance concrete can be considered the technology of the future. This Prague tram stop, with a minimal share of human labour, is So Concrete's first intervention in the field of urban furniture.
A bench and information panels complete the stop. It is, therefore, a comprehensive solution for the entire space. The aim was to show the functionality of the technology and the high aesthetic added value.

The location was not chosen by chance, Prague is a modern metropolis with highly developed public transport. The location of the Výstaviště tram stop near the Stromovka park is located in the Prague 7 district, which is perceived as a progressive, modern and creative district, home to a number of artistic and cultural institutions.


The design

The parametric design of the tram stop, the location, the shapes of the ribs and the columns – all make maximum use of the effectiveness of nature-proven solutions. Záviš Unzeitig, designer at So Concrete, explains how the design process inspired by natural influences works: “Already during the design phase, the structure is statically analysed, and with the help of topology optimization, it is then possible to reduce the volume of material used. At the same time, the aesthetic qualities and structural requirements are maintained. The resulting morphology of the ribs reflects the actual behavior of the structure under load and thus directly shows the forces that take place in it. Thanks to the optimization, we were able to remove places with less usability from the structure and save 60% of the material. The result is a perforated fine structure that can withstand the same load as a solid concrete slab.”


The digital process

The stop design was developed using a digital workflow based on parametric design in Grasshopper (Rhino). “We use this framework to design our own software tools that cover processes ranging from geometry generation, topology optimization, static analysis, 3D slicers, and inverse kinematic solvers to post-processors. Our focus on creating custom digital solutions allows us to quickly adapt to a wide range of standard file formats and geometry types. Working closely with our customers to optimize the input digital models for our production process enables a quick transition from idea to physical object,” explains Dimitry Nikitin, robotic engineer at So Concrete. For the static verification of the design of the stop structure and its final appearance to be completely independent, the leading engineering company Stráský, Hustý a partneři, was approached for validation.


Production and materials

The stop is composed of several structural segments, for which different types of concrete and 3D printing approaches were used. The roof and the bench were manufactured using robotic 3D printing. The material – concrete – was chosen according to function and load. For example, steel-fiber reinforcement was not used for the bench seating area, as opposed to the roof, which contains this reinforcement. To produce the column heads, the robot milled and printed the moulds into which the final heads were subsequently printed.


Technology for the future

So Concrete technology is based on three pillars: topology optimization, ultra-high-performance concrete (UHPC) and robotic 3D printing. Thanks to the integration of these principles, the basic structure of the stop could be produced within 24 hours. The topology optimization allowed more than half of the material to be saved and to achieve natural aesthetics. The properties of UHPC make it possible to manufacture such subtle self-supporting structures using a minimum amount of steel. Robotic 3D printing not only brings the advantage of saving human labour, but also the possibility of producing such complex shapes without the need to use moulds or formwork.