Central line (London Underground) and Great Eastern Railway buildings east of , from when the line to Epping was a rural branch line. In terms of total passengers, the Central line is the busiest on the Underground. In 2011/12 over 260 million passenger journeys were recorded on the line. It currently operates the second-most frequent service on the network, with 34 trains per hour (tph) operating for half-an-hour in the westbound direction during the morning peak, and between 27 and 30 tph during the rest of the peak. This makes the Central line the busiest and most intensively-used railway line in the United Kingdom:
London Underground rolling stock numbering and classification London Underground rolling stock numbering and classification Rolling stock used on the London Underground and its constituent companies has been classified using a number of different schemes. This page explains the principal systems. The numbering and classification of electric multiple unit stock on the London Underground is usually related to the type of line that the trains are used on. There are two distinct types of line: 'Sub-surface' lines (earlier lines built on the cut-and-cover method, which use trains of similar size to those on the national railway network), and 'Tube' lines (deep-level lines, built to a more restricted size).