London Underground L Stock London Underground L Stock London Underground L Stock was a clerestory-roofed rail stock built for the District line in 1932 and subsequently absorbed into the London Underground Q Stock, being redesignated Q31 Stock. The L Stock trains were built to provide additional rolling stock for the eastward extension of the District Line from Barking to Upminster. Two new electrified tracks were added parallel to the existing steam-operated LMS lines, including several new stations such as Upminster Bridge. Forty-five cars were built by the Union Construction Company, eight were driving motor cars and the rest were trailers. The eight motor cars,
London Underground infrastructure lines share all their stations and most of the track with other lines. The Bakerloo, Central, Jubilee, Northern, Piccadilly, Victoria and Waterloo & City lines are deep-level tubes, with smaller trains that run in two circular tunnels with a diameter of about , lined with cast-iron or precast concrete rings, which were bored using a tunnelling shield. It is these that were the "tube" lines, although since the 1950s the term "tube" has come to be used to refer to the whole London Underground system. Many of the central London deep-tube line stations, such as those on the Central and