instead of a ticket, first went on sale in 2003. The scheme was originally managed as a PPP by TranSys; TfL bought the rights to the Oyster card name in 2008. On 7 July 2005 three bombs exploded on underground trains, two on the Circle line at Aldgate and Edgware Road and the third on the Piccadilly line between King's Cross and Russell Square. Later the same day a bomb exploded on a bus in Woburn Place. Four suicide bombers had killed themselves and fifty-two other people, and it took over a month before underground services had been restored. In 2007 the East London line, operated as an isolated shuttle since 1939, closed so that it could be converted into a London Overground line. In December 2009 the Circle line changed from serving a closed loop around the centre of London on the north side of the River Thames to a spiral serving Hammersmith. On the Jubilee line a seventh car was added to all trains, in 2006 and a new signalling system allowing automatic operation was commissioned in 2011. On the Victoria line, new trains were introduced between July 2009 and June 2011, and a new signalling system has allowed 33 trains per hour from January 2013. The sub-surface (Metropolitan, District, Circle and Hammersmith & City) lines have been upgraded, with new air-conditioned S Stock. Also, the sub-surface track, electrical supply and signalling systems are also being upgraded in a programme allowing an increased peak-hour capacity by the end of 2018. A single control room for the sub-surface network is to be established in Hammersmith and an automatic train control (ATC) system will replace signalling equipment installed from the 1940s. During the London 2012 Olympic and Paralympic Games, the Underground saw record ridership levels, with over 4.3 million people using the Tube on some days. This record was subsequently beaten in future years, with 4.82 million riders in December 2015. In 2013, the Underground celebrated its 150th anniversary, with celebratory events such as steam trains and installation of a unique Labyrinth artwork at each station. In the 2010s, the Crossrail project was built at a cost of £18.8bn to connect two mainline railways with a new east west tunnel under central London, similar to Paris' Réseau Express Régional. Designed to increase rail capacity and reduce cross London journey times, the line opened as the Elizabeth line in May 2022.