Travelling Membrane Roof in Vienna City Hall

This 34.21 x 32.52 m extendable roof structure provides protection against sun and rain and allows the courtyard to be used for balls, ­concerts and other events. The entire membrane, cable and cross-girder construction is assembled on roller bearings in tracks. The travelling roof is operated by motors attached to the cross-girders, with pinions engaging in toothed racks welded to...