London Underground rolling stock the 150th anniversary of the opening of the Metropolitan Railway special services ran in January 2013 using a restored 1892 "Jubilee" carriage, 1898–1900 bogie carriages, steam locomotive No. 1 and electric locomotive "Sarah Siddons". Further events are planned in 2013 for Locomotive No. 1, "Sarah Siddons" and the Jubilee carriage, including a "Steam back on the Met" scheduled for May. To celebrate the 150th anniversary of the District Railway the London Transport Museum are restoring a three-car Q Stock train to run on the District Line as special services during 2018. After the District Railway had electrified in 1907 it
London Underground The London Underground is frequently studied by academics because it is one of the largest, oldest, and most widely used systems of public transit in the world. Therefore, the transportation and complex network literatures include extensive information about the Tube system. For London Underground passengers, research suggests that transfers are highly costly in terms of walk and wait times. Because these costs are unevenly distributed across stations and platforms, path choice analyses may be helpful in guiding upgrades and choice of new stations. Routes on the Underground can also be optimized using a global network optimization approach, akin to routing