The heyday of railway stations in the 19th century saw great halls for train terminals in many European cities. Typically stations were erected outside the historic cities, which soon grew around them, turning the tracks into a hindrance to urban development. This is especially true for the city of Stuttgart in southwest Germany, which lies in a tight valley. The existing station is a terminus and difficult to link to the growing European high-speed rail network. A new high-speed line is being built in an underground tunnel at a right angle to the existing tracks. This will free up space for a new urban quarter. The project is called “Stuttgart 21” and envisages the new tracks up to 12 metres below the old, whereby the station building from 1922, which is listed as historic monument (architect Paul Bonatz and Friedrich EugenScholer), will be retained. The station will become the nucleus of the urban development and an interface between the old and the new city. It will give Stuttgart a much improved link to Europe and, even more, a new centre. The “Schlossgarten” (castle gardens) as the green heart and most important public green space in Stuttgart, will be extended above the new station.
The most striking impression of the new subterranean station, which ingenhoven architects have designed, will be its brightness and visual openness, which combines aesthetic with security advantages. The new station has a beautiful white concrete structure subjected only to compressive loads with minimal construction thickness. The thickness of the optimised shell structure was reduced to one hundredth of the span, resulting in the use of much less material. The reusability of the formwork and the prefabrication of modular components facilitate efficient construction. The development of a special concrete enables the visibility of the structure due to the exposed concrete surface without fire-rated cladding.
The station concourse will be illuminated by natural light through large circular “light eyes” during the day. The “light eyes” will establish the presence of the subterranean station in the minds of passers-by above. The 16 tracks with 17 platforms of the existing terminus are reduced to eight tracks with four platforms by increasing efficiency and reducing the travel times.
The intelligent use of natural energies and resources avoids CO2 emissions. The “zero-energy station” requires no supplied energy for heating, cooling or mechanical ventilation. This is achieved by benefiting from the warm ground water and warm air flow from the tunnels. Additionally, own-generation of energy is foreseen by PV-modules assembled on the roof of the station building.
The integration of the new station with its new public spaces and green areas into the urban grid creates a new quality for the city centre of Stuttgart.
The unique nature-like structure of the station concourse creates a long-lasting aesthetic elegance of the loadbearing structure. The design of Stuttgart 21 translates the new era in rail transportation into a contemporary form.