In 1974, World Cup games were played in the current AWD Arena in Hanover, the former Lower Saxony Stadium. With an eye on the 2006 World Cup, the stadium was brought into line with FIFA requirements and all spectator seats were covered. The membrane roof made of translucent ETFE foil plays an important role in sustainable planning as required by FIFAâ€™s â€śgreen goalâ€ť programme. It fosters grass growth and significantly extends the lawn replacement cycle. At 10,200 m2, the roof over the AWD Arena is the largest single-ply membrane roof in the world.
The primary goals of the stadium renovation included maintaining the stadiumâ€™s old lines and integrating it harmoniously into the park landscape. The new structure fits modestly and naturally into its environment and the existing geometry of the sports facilities. Two separate wheel and spoke systems with radial girders divide the entire roof into two different areas. The trapezoidal sheet metal outer ring of the roof matches the shape of the old roof structure, the inner ring made of transparent ETFE foil forms a kind of â€śroof within a roofâ€ť.
A ring cable on the playing field side of the roof and a steel tube where the membrane meets the sheet metal roof serve as supports for the radial girders. Secondary beams run parallel to the ring cable at four metres distance. With horizontal posts and diagonal bonds, the first two and the last two secondary beams are designed with their top booms as trussed beams. These beams assume the tensile forces of the radial cables. To prevent the cables from sagging under the weight of snow, for instance, they are supported by the top booms of the secondary beams and stretched across the horizontal trussed beams. The 34 flat, horizontal, obliquely angled foil rectangles ranging from 18 to 24 metres are held by piping with a patented EPDM seal. The construction was not only within the planned budget, but was also completed three months ahead of schedule.