London Underground Metropolitan Line

London Underground Metropolitan Line is a Transport for London operated tube line in London, England. Running between Aldgate, Amersham and Chesham in Buckinghamshire, with branches to Watford in Hertfordshire and Uxbridge in the western London Borough of Hillingdon, it is coloured magenta on the tube map.

The line is 41.4 miles (66.7 km) in length and serves 34 stations. Unlike the deep-tube railways, its tunnels are just below the surface ("cut and cover") and are of a similar size to those on main lines.

The line is a suburban railway and one of only two Underground lines to cross the Greater London boundary (the other being the Central line). It is also the only Underground line with an express service at peak times. The longer distance between stops allows trains on this line to achieve the system's highest speeds of over 60 miles per hour (100 km/h) on some sections.

History
In 1863 the Metropolitan Railway began the world's first underground railway between Paddington and Farringdon with wooden carriages and steam locomotives, but its most important route became the line north into the Middlesex countryside, where it stimulated the development of new suburbs. Harrow was reached in 1880, and the line extended as far as Verney Junction in Buckinghamshire, more than 50 miles (80 km) from Baker Street. From the end of the 19th century, the railway shared tracks with the Great Central Railway out of Marylebone. The central London lines were electrified by 1907 but electric locomotives were exchanged for steam locomotives on trains heading north of Harrow. After the railway was absorbed by the London Passenger Transport Board in 1933 the line was cut back to Aylesbury. Steam trains ran until 1961, when the line was electrified to and services were curtailed at Amersham. The Hammersmith & City line was shown on the tube map as a part of the Metropolitan line until 1990, when it appeared as a separate line. The current S8 Stock trains entered service between 2010 and 2012.

The section between Aldgate and Baker Street is shared with the Circle and Hammersmith & City sub-surface lines; between Rayners Lane and Uxbridge with the Piccadilly line; and between Harrow-on-the-Hill and Amersham with the Chiltern Railways main line. The track is mostly below-ground between Aldgate and Finchley Road, save for at Barbican and Farringdon stations, as well as the Baker Street platforms. Baker Street is the southbound terminus for some trains not continuing on to Aldgate. Most of the route has two tracks, except for the single-track Chesham branch and a four-track section between Wembley Park and Moor Park that allows fast and semi-fast services to overtake "all stations" trains. There are four tracks between Wembley Park and Finchley Road, but only the outer ones are used by the Metropolitan line's non-stop trains: the inner pair was transferred to the Bakerloo line in 1939 (becoming the Jubilee line in 1979) with services calling at all stations. The disused Metropolitan line platforms at Willesden Green and Neasden are still in place despite Metropolitan line services having been withdrawn in 1940.

In 1927, T Stock trains were introduced.

On 12 June 1961, A60/62 Stock trains were introduced.

In 1962, the T Stock was withdrawn and the line was converted to a full A60/A62 operation.

On 31 July 2010, brand new S8 Stock trains were introduced.

On 26 September 2012, the A60/A62 Stock was withdrawn and the line was converted to a full S8 Stock operation.

There is a long-term aim to divert the two-station Watford branch to Watford Junction, resulting in the closure of Watford station and the opening of two new stations. This project would provide a link with the London Overground Watford DC Line and provide an interchange with the West Coast Main Line. Previously announced for completion by 2020, the future of the project is now uncertain, due to a funding shortfall.

Current Route
The Metropolitan Line operates via these primary locations.

Metropolitan Main Line

 * Aldgate
 * Liverpool Street
 * Moorgate
 * Farringdon
 * King's Cross St Pancras
 * Euston Square
 * Great Portland Street
 * Baker Street
 * Finchley Road
 * Wembley Park
 * Preston Road
 * Northwick Park
 * Harrow on the Hill
 * North Harrow
 * Pinner
 * Northwood Hills
 * Northwood
 * Moor Park
 * Rickmansworth
 * Chorleywood
 * Chalfont & Latimer
 * Amersham

Chesham branch

 * Chesham

Uxbridge branch

 * West Harrow
 * Rayners Lane
 * Eastcote
 * Ruislip Manor
 * Ruislip
 * Ickenham
 * Hillingdon
 * Uxbridge

Watford branch

 * Croxley
 * Watford