In July and August 2011, the track of the London Underground District Line was completely renovated between Paddington and High Street Kensington stations in the city centre. In addition to new ballast and new rails, the track section of this very busy Underground line was fitted with new sleepers incorporating Getzner pads. London Underground installed around 8,000 sleeper pads for concrete and wooden sleepers. As well as protecting the track superstructure, the elastically mounted sleepers protect residential buildings from vibrations. This concerns the large number of residential buildings located directly adjacent to the tracks in central London.