The new airport train station Stuttgart 21
Stuttgart 21 is one of the largest and most complex infrastructure projects in Europe. Nevertheless, many people know only that a futuristic-looking through station is to replace the old terminus station in Stuttgart city centre. There is, however, considerably more to the project: placing the tracks underground leaves the land above free for urban development. Three more stations and tunnels with a total length of approximately 57 km are also planned. The airport tunnel with its pair of 2.2 km long tubes being one of them.
Airport long-distance train station
The airport tunnel was driven at depths of up to 30 m using conventional tunnelling techniques. Constructing the tunnel was demanding, because, among other things, it ran under the A8 motorway and several exhibition halls of Stuttgart Messe. The new long-distance and regional train station on the Messe piazza is in the immediate neighbourhood of the airport terminal, local surface and light urban railway stations. The new station is an important component of Stuttgart 21, because it connects the airport and the Messe to long-distance and regional rail services as well as the bus network. This brings other towns and cities within easy reach. At the moment, travellers have to make a half-hour journey to reach the station in the city centre and continue to their destinations from there.
One system, several solutions
So that the new tunnel and station continue to meet future requirements, both are fitted out with the appropriate safety technology. For instance, in each of the tubes at the airport station there is a smoke extraction duct above the two 430 m long platforms. The site team working for the consortium made use of several NOE-Schaltechnik systems for constructing the ducts. These included NOEtec and NOEalu L. NOEtec is a flexible modular system that was developed for engineering and building structures. Tailored solutions can be created using the system’s very few components. For example, the NOE operatives on site assembled four working carriages and two deck formwork carriages from NOEtec system parts to transport the individual formwork elements into the tubes and install them in position. The deck formwork carriages have a plan area of 5.0 x 16 m and were used to cast the floor of the smoke extraction duct. The working carriages are 4.5 x 16 m in plan and allow the site teams to carry out tasks such as concreting.
The smoke extraction ducts with openings through which air and smoke can be drawn are to be seen on the left-hand side of the image
NOE systems make work easier
All six carriages are designed to allow site vehicles to pass under them while work continues on the platforms. They stand on rails and are moved from one concreting section to the next. The two 25 tonne deck formwork carriages are driven by an electric motor. The working carriages, which are lighter, are moved using a site vehicle. The formwork table on top of the deck formwork carriage rests on hydraulic jacks, which can be lowered by up to 50 cm to allow the formwork to be stripped after the concrete has hardened. As soon as these intermediate floors were complete, NOEalu L formwork was erected for the sidewalls of the smoke ducts. NOEalu L, as the name suggests, consists of aluminium and has a panel weight of less than 20 kg/m². As a result, it is extremely lightweight and easy to manoeuvre by hand. Moreover, NOEalu L has the advantage of a low transport volume due to its 10 cm installation height, and yet can withstand a concrete pressure of 60 kN/m².
The carriages are designed to allow site vehicles to pass under them
Main access
The main access to both station platforms is through a surface-level reception building and a 20 m diameter shaft centrally positioned between the two tunnel tubes. The internal intersection areas between the two tunnel tubes and the shaft were concreted using special formwork designed, manufactured and assembled by NOE. The external intersection areas were constructed by the consortium team using NOEtop R 275 formwork system. This system was developed for circular vertical structures with radii from 2.75 m. To ensure that it can be used immediately, NOE supplies it already set at the radius required for its first use. The formwork can be set quickly and precisely to the radius required for its next use. The circular formwork can be extended to the required height without problem using the NOEtop R 275 extension clamps. NOEform formwork facing is used for this formwork as standard. It produces homogeneous concrete surfaces without pores or trapped pockets of air. So that the concrete appearance matched that of the previously cast shaft, NOE added a second formwork liner for the long-distance train station project. Once Stuttgart 21 is complete, the long-distance and regional train station will considerably improve the transportation network of the region and Baden-Württemberg, as well as making it easier to reach the airport and trade fair centre.
