The new €37.5m (£27.6m) Transfer Terminal at Arnhem Central Station in the Netherlands is the result of an ambitious 20-year project – master-planned by UNStudio – to redevelop the wider station area; the largest post-war development in Arnhem.
The 21,750m2 Transfer Terminal features a dramatic twisting structural roof geometry, which enables column-free spans of up to 60m in the transfer hall. Taking references from the continuous inside/ outside surface of a Klein Bottle, UNStudio aimed to blur distinctions between the inside and outside of the terminal by continuing the urban landscape into the interior of the transfer hall, where ceilings, walls and floors all seamlessly transition into one another. The structure of the roof and twisting column was only made possible by abandoning traditional construction methods and materials; much lighter steel replaced concrete – originally intended for the station – and was constructed using boat building techniques on a scale never before attempted.
Integrating the naturally sloping landscape distinctive to Arnhem, UNStudio conceived the Transfer Terminal as a flowing, utilitarian landscape of different functions stacked up to four storeys above ground and two below. The key space is the 5,355m2 main Transfer Hall, topped with a dynamic, undulating roof form.
In the development of the design, the practice used a series of conceptual structural tools to mold the geometry of the terminal landscape to accommodate the different program functions. These include the use of ‘V-walls’, a load-bearing concrete structure that absorbs the differences in the required grids and provides daylight to the below ground levels. The spaces between these elements also form the public access from the underground car park to the other components.
Working with structural engineers Arup, a space without columns was produced, forming an architectural expression designed around the ways people will intuitively use the space.
The intention of the building is to enable people to move around naturally and intuitively, to make them feel calm and comfortable. Using the data supplied by the municipality of Arnhem, the Arup team generated calculations showing the passenger movements. When the initial design process took place, Arup had not yet developed its now well-known MassMotion software for dynamically modelling pedestrian flows, so the team used models developed in the early 1970s by J.J. Fruin, which were generally regarded as the industry standard at that time. UNStudio then focused on the ‘Klein Bottle’ analogy to design the passenger terminal around activities taking place in the transfer hall.
— Ben van Berkel
Founder and Principal Architect