London Underground A60 and A62 Stock

The A Stock (also known as the A60 and A62 Stocks ) is the type of train used on the Metropolitan Line of the London Underground. It was built in two batches (A60 and A62) by Cravens of Sheffield in the late 1950s. The trains replaced all the previous stock then used on the Metropolitan Line (such as F Stock, P Stock, T Stock and locomotive hauled carriages). The A Stock started to be replaced by new trains of S Stock from 2010.

The A Stock is currently the oldest type of train in passenger service on London Underground, and the last rolling stock to have independent motoring and braking controls. In addition, it has no automated announcements.

Development and introduction
The core design of the A Stock was formulated by W S Graff-Baker of the London Passenger Transport Board as part of the electrification of the Metropolitan Line from to  and  under the 1935–1940 New Works Programme. The project was delayed by the events of World War II and the lack of funds available during the austerity period which followed the war: however, in 1946 two experimental trailers similar in exterior appearance to the production trains were built using underframes of the T Stock. The trailers were scrapped when the trials concluded.

When the electrification project commenced in 1959, London Transport placed an order for 31 trains of the A60 Stock, which were built by Cravens of Sheffield. The first A Stock units (5004 and 5008) entered passenger service, beginning with the Watford service in August 1959. Twenty-seven trains of the A62 Stock were built in 1962–63 to replace the F and P Stocks on the Uxbridge service. The roll-out was completed by December 1963.

The trains were designated as the A Stock to mark the electrification of the Metropolitan Line to Amersham. However the A Stock was also used on the former East London Line (then a branch of the Metropolitan Line) between June 1977 to April 1985, May 1987 to 24 March 1995 and from 25 March 1998 until the line's closure for conversion to the London Overground network on 22 December 2007.

Design
The London Underground A60 and A62 Stocks were mainly designed as a compromise between the needs of longer distance “outer suburban” passengers on the outer reaches of the line and short distance “urban” passengers over part of the heavily used Circle and Hammersmith & City lines. For this reason the trailer cars feature three sets of doors per car.

A distinctive feature of this stock is the use of “tranverse” seating only. As it was designed for journeys which may last over an hour, most of the seating is of the high capacity 3 + 2 arrangement, oriented across the car's width as opposed to a longitudinal layout, where seats are arranged along the sides of the carriage. In addition, four tip up seats are provided at the rear of the driving motor. Nevertheless, despite each 8-car train seating 448 passengers, these trains provided fewer seats than the locomotive-hauled and T stock trains which they replaced: however, the stock provides more seats than the S Stock, which began replacing the A Stock from 31 July 2010. For the convenience of long-distance passengers the A stock is also equipped with luggage racks and umbrella hooks, being the only stock on the system to have these features, commonplace on most National Rail passenger stock.

The A60 and A62 stocks are identical by appearance but the manufacturer of the compressors are different: The compressors fitted to A60 cars are of the Westinghouse DHC 5A type, while A62 cars have the Reavell TBC 38Z type: the different sound of these can act as an identifying feature.

At 2.946 m these are London Underground's widest trains.

When the trains were refurbished by Adtranz (now Bombardier) Derby between 1993 and 1998, car end windows were installed and the overall livery was revised. At the time of refurbishment the line on which they ran had a low priority for receiving new trains.

Operation
A unit of the A stock consists of four cars: two powered driving motors at each end and two non-powered trailers in between. Each unit is further divided into two sets, consisting of a driving motor and trailer which are semi-permanently coupled. The A Stock operates in a two-unit formation of eight cars on the Metropolitan Line, between and, ,  and  stations.

Until 11 December 2010, a single unit operated on the Chesham branch at off-peak hours, with two two-unit services running directly to or from Aldgate at each peak hour period. Since 12 December 2010, the off-peak single formation was replaced by a half-hourly two-unit service from.

The A stock also operated in a single-unit formation on the East London Line until 22 December 2007 when the line was closed for extension and conversion works.

When built they had a top speed of 70 mph (World's fastest 4-rail train), and operated at this speed until the late 1990s/early 2000s. They are permitted to travel at no more than 50 mph to improve reliability. Despite this, these trains are the fastest on the London Underground network. The A Stock is the last rolling stock on the London underground that still feature independent brake and traction control. The A stock is also the last remaining stock currently on the London Underground not to have an automated public address system.

Other areas of operation
In addition to the Metropolitan line, the A Stock is permitted to traverse the following sections, subject to the following restrictions:

Roster
Cars of the A Stock are identified by a four-digit number. The first digit identifies the type of car (driver or trailer) and the last three digits identify the set number (Numbers 000 to 231). The numbering system of the A stock upon introduction were as follows: In further detail:

Renumberings: a. 5034 and 5008 swapped number on July 1985. The new 5008 and 6008 later became (set) No.234 on September 1994. b. No.9 renumbered No.235 on September 1994. c. No.28 renumbered No.232 on June 1985. d. 5036 renumbered 5116 on April 1993. e. No.117 renumbered No.233 on August 1985; No.37 renumbered No.117 on April 1993. f. 5208 renumbered 5218 on August 1992. g. 5209 renumbered on March 1993.

Converted works vehicles: s. Sandite dispenser car.

Withdrawals: S1. S2.

Withdrawal
The London Underground A60 and A62 Stock reached its 50th year of passenger operation on 12 June 2011. The age of the fleet meant that spare parts were becoming harder to obtain, and a number of cars had to be cannibalised to keep the rest of the fleet in operation while the S8 Stock is being introduced.

The A Stock operated on the East London line until the cessation of Underground services on 22 December 2007. Class 378 Capitalstar units now operate on the line as part of the London Overground network after the first phase of extensions was completed on 23 May 2010.

The first S8 Stock unit was introduced into passenger service on 31 July 2010. Although physically similar to the S7 Stock for the District, Circle and Hammersmith & City lines, the main differences are the layout and quantity of seats and the provision of two active sand hoppers for each rail due to the different conditions at the country end of the line. The final withdrawal of the A Stock after the introduction of the S8 Stock commenced on 9 and 10 October 2010, and is expected to be complete by the summer of 2012. As of 28 February 2012, 4 more trains were withdrawn for scrapping.

In February 2012 the London Transport Museum offered luggage racks from withdrawn A stock for sale.