and reflects the light of the concourse back at night; the structure appears to be silver from the outside. Narrow slits between the membranes are left open over the hall arches, forming a total of 67 skylights. The roof area is about 33,000 square metres (of which 29,000 square metres is composed of glass fibre membrane), which covers a surface area about 24,500 square metres. The architects who won the competition emphasised their entry's relatively easy installation, low weight and low maintenance costs (self-cleaning). According to the Deutsche Bahn specifications, cooling is not required due to the "tent construction" of the roof even in bright sunlight. The restoration was carried out between February 2001 and July 2006 with trains running through the station. 800 tons of material were installed in the two outer halls from elevated work platforms and more than 1600 tons of material were installed in the central hall. On 15 May 2001, workers began with the removal of the old glass roof. Some of the old steel beams were rebuilt and some new ones have been inserted as wind bracing between the hall arches. Secondary structures were then built to attach the membranes on the beams. A total of more than 100,000 screws were installed, some of which also replaced rivets on the historic hall arches. A service lift was also installed. The planning began in 1997 and originally a full canopy covering the outer platforms was envisaged, but this was rejected in 2000. Instead it was decided to take up an option to extend the two outer roofs by 200 metres to the east above the outer platforms using a membrane roof. The membrane roof has been damaged several times during bad weather. In the winter of 2010/2011, eight cracks, which were up to two metres wide, were formed. Responsibility for the damage was still being contested in court in January 2013. Main entrance and lobby The main entrance of the station building forms part of a large circular portal window arch. The portal is installed in the massive Avant-corps that dominates the centre of the facade. In addition there is a statue of Saxonia, the embodiment of the spirit of Saxony, which is arranged between allegories of science and technology. Both the portal of the entrance building and the clock towers on both sides show the association of the station with the architectural style of