Preserving concrete thin shells. The case of Deitingen South Station by Heinz Isler (1968-1969)

After World War II the research about the double curvature structures in reinforced concrete was a frontier in the field of typological, spatial and expressive innovation. Among the principal leading figures was the swiss engineer Heinz Isler with his methods called “form finding” based on the use of physical modeling to determine the form and subsequently investigate its stability. When a concrete shell is shaped using a hangingmembrane model, it assumes an ideal form using a minimum of materials, with minimal deformations and in compression only. This is only the first step in the process of finding the form. Then one has to do the exact structural analysis, the layout of the reinforcement and prestressing elements, and the detailing, to deal with construction problems, and finally to carefully observe the structure in use. The need to protect the works of Heinz Isler has slowly been bearing fruit in recent years. This highlights in a very special way the crucial point of the debate on the protection of modern and contemporary architecture: the recognition of their architectural and cultural values, and consequently the difficulties of the institutions responsible for undertaking their preservation. The paper intends to investigate the case of the Deitingen service station built in 1968-1969 which represents a fortunate phase in this process and shows how the factors linked to the durability of structures play a small role in the decision-making processes regarding the future of these works. The key role is played by the significance and values that acquires (or loses) over time.