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Rolling stock used on the London Underground and its constituent companies has been classified using a number of schemes. This page explains the principal systems for the rolling stock of the Central London Railway (CLR), the Underground Electric Railways Company of London (UERL), the District Railway (DR) and the Metropolitan Railway (MR). For information about individual classes of locomotives and other rolling stock, see London Underground rolling stock.

Electric Multiple Units

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 in the central area of the network.

Sub-surface lines were built using the cut-and-cover tunnelling method and use trains of similar size to those on the National Rail network. These are the Circle, District, Hammersmith & City, Metropolitan (and formerly East London) lines.

Tube lines are deep-level lines, built to a more restricted loading gauge using circular tunnelling shields or tunnel boring machines. These are the Bakerloo, Central, Jubilee, Northern, Piccadilly, Victoria and Waterloo & City lines. Outside of the central area, both types of trains run on the surface.[a]

Unit Classification

The method of classification depends on the type of line the train operates on:

Tube Stock

Tube Stock is classified by the anticipated year of delivery at the time of ordering.[b]

This system was inaugurated by the London Passenger Transport Board (LPTB) with the 1935 Stock. The large number of broadly similar Tube trains built for the UERL during 1922-1934 were called (and are commonly still referred to as) Standard Stock (officially re-christened Pre-1938 tube stock upon rehabilitation), although there were many detail differences. They replaced the UERL's original Gate Stock (itself known as Standard Stock before the introduction of the then-new Pre-1938 tube stock), introduced for the opening of the Bakerloo, Piccadilly and Hampstead (Northern) lines and the replacement of the City & South London Railway's locomotive and carriage sets, the Watford Joint Stock of the Bakerloo, the Great Northern & City Railway's surface gauge stock, and the CLR's Tunnel Stock and Ealing Stock (which in turn comprised DMs of 1903 and 1915 vintage constructed to replace locos hauling trailers of 1900 vintage).

Sub-surface Stock

Sub-surface Stock is classified by a letter, usually issued sequentially, and which is sometimes followed by the last two digits of the year of delivery, e.g. G23 Stock . This system was commenced by the DR for its stock. When the LPTB was formed, the ex-Metropolitan Railway units were incorporated into this series (types MV, MW, T, V, VT and W). By 1960, most letters had been allocated, and the decision was taken to re-issue A (for the Amersham electrification) to the new Metropolitan stock.[1] The next sub-surface types were built for the Circle and District lines, and the opportunity was taken to allocate C (for the Circle line) and D (for the District line) respectively, omitting B.

Types of Unit

On most lines, trains are formed from a pairing or triplet of units. Units are 'single-ended', where there is a driving cab at one end only, or 'double-ended', where there is a driving cab at both ends. In addition, some units have no driving cabs, and thus must always be included in the middle of a formation of units.

Car Classification

The different types of car used to make up electric multiple units are referred to by a series of codes, described below:

Code Description
DM Driving Motor car (with motors and a driving cab)
NDM Non-Driving Motor car (motored, but with no driving cab)
UNDM Uncoupling Non-Driving Motor car (as NDM, but with controls at one end to permit uncoupling and shunting, but not full driving facilities)
MS Motor Shunting car (as NDM, but with provision to split from the adjacent MS as required in depots)
T Trailer car (no motors or driving cabs)
CT Control (or 'Driving') Trailer car (with a driving cab, but no motors)

On most lines, the end cars of units are described as 'A' end cars or 'D' end cars ('B' end until the 1930s). In general, the 'A' end is the north or west end and the 'D' end is the south or east, but the reverse applies on the Bakerloo line. On lines with a loop at the end that allows trains to turn round (e.g. at Heathrow Terminal 4 on the Piccadilly line and Kennington on the Northern line), this system cannot apply rigidly.

Car Numbering

Each car carries its own unique number (although many numbers below 10000 have been reused by newer cars after the withdrawal of older trains), and unit numbers are not applied. Although car numbers have been allocated in a variety of different series over the years, two basic principles can be identified:

1931 Numbering Series

In 1931, the UERL began a major renumbering of all its multiple unit cars. The series was adopted by the LPTB in 1933 and renumbered stock inherited from the MR was incorporated into the UERL's series. The table below shows the number ranges used for the inherited stock and initially used by the UERL/LPTB for new stock (including the LPTB-designed M and N Stock and Q38 Stock DM cars - Q38 Stock trailers were allocated numbers in one of the new numbering series described later):

Number Series Car Type Line Type Numbers for Inherited Stock Numbers for New Stock Numbers for Converted Stock
1-37 DM Sub-surface
Surviving unrefurbished B Stock (not renumbered in 1931)
1000–1094 T
1700–1717 CT
2000-2999 DM Sub-surface
2200-2247 Hammersmith line stock
2500-2769 Main line stock[c]
2900-2940 Northern City line stock
3000-3999 Tube 3000-3069 and 3282-3688 ex-LER
3912-3999 ex-CLR
3723-3784 DM cars that changed ends
4000-4999 Sub-surface
4000-4390 and 4591-4645 4391-4437 4620-4642 (evens) ex-CT cars
5000-5999 CT Tube 5000-5359 ex-LER
5928-5999 ex-CLR
6000-6199 Sub-surface
6000-6022 6100-6109 ex-DM cars
6200-6999 Sub-surface
6201-6264 Hammersmith line stock
6500-6735 Main line stock
6900-6919 Northern City line stock
6558/6559/6561/6562 ex-trailers
6736-6755 ex-hauled stock
7000-7999 T Tube 7000-7059 and 7190-7570 ex-LER
7901-7999 ex-CLR
8000-8999 Sub-surface
8000-8048 Composites
8200-8258 ex-DM cars
8700-8780 ex-DM cars
8049-8083 Composites
8084-8095 Composites, ex-Third class
8786-8799 ex-DM cars
8801-8812 ex-Composites
8813-8848 & 8900-8904 ex-DM cars
9000-9999 Sub-surface
9200-9259 Hammersmith line stock
9400-9799 Main line stock
9582-9599 ex-DM cars
9900-9968 Northern City line stock
9479-9482 ex-CT cars
9800-9844 ex-hauled stock


Later Developments

This standard number series proved to be short lived; from 1935 onwards a variety of different series have been used, so the current list of numbers looks rather random. The table below sets out the numbering systems used for each type of London Underground stock:

Number Series Stock Number Ranges Allocation of Numbers
11-26 1986 11-16 DM
21-26 NDM
Formed 1x+2x.
100-897 1973 100-253 DM
300-453 UNDM
500-696 T
854-897 DM (from double-ended units)
All cars in a unit had same last two digits, except double-ended units, which were formed in a series from 854+654+855.
1956, 1959, 1962 1xxx DM
2xxx T
9xxx NDM
All cars in a unit had same middle two digits: fourth digit even for A-end cars and odd for D-end cars.
1967, 1972, 1983 3xxx DM
4xxx T
All cars in a unit had same last two digits: second digit even for A-end cars and odd for D-end cars.
1960 39xx DM
49xx T
Fourth digit was even for A-end cars and odd for D-end cars; the original trailers (converted from Standard Stock) were later replaced by trailers converted from 1938 Stock, whose numbers did not correspond with the DM cars.
A & C 5xxx DM
6xxx T
A Stock: four-car units, where all cars in a unit had same middle two digits, fourth digit even for A-end cars and odd for D-end cars;
C Stock: two-car units, where both cars had same last three digits.
D 7xxx DM
8xxx UNDM
17xxx T
All cars in a unit had same last three digits, except double-ended units, which were formed in a series from 7500+17500+7501.
1935, 1938, 1949 10xxx DM (A-end)
11xxx DM (D-end)
12xxx NDM (T when prefixed by "0")
30xxx UNDM (A-end)
31xxx UNDM (D-end)
70xxx T (ex-Standard Stock)
90xxx DM (nine-car unit A-end)
91xxx DM (nine-car unit D-end)
92xxx NDM (nine-car unit; T when prefixed by "0")
A-end & D-end DM cars had same last three digits; trailer numbers were not matched.
O & P,
Q38 trailers
13xxx A-end (DM or T when prefixed by "0")
14xxx D-end (DM or T when prefixed by "0")
A-end & D-end DM cars had same final three digits, trailer numbers were not matched. (Q38 Stock DM cars were numbered 4xxx in the original 1931 number series.)
1xxxx (2nd use) 2009 11xxx DM
12xxx T
13xxx NDM
14xxx UNDM
Eight car units formed from two four-car 'blocks' in which the last three digits of each car are the same; fifth digit even for A-end cars and odd for D-end cars.
2xxxx (1st use) R 21xxx DM (A-end)
22xxx DM (D-end)
23xxx NDM
The third digit indicated the position of the car in the unit, A-end to D-end, from 1 to 6 in six-car units and 5 & 6 in two-car units. Each car in the unit had same last two digits.
2xxxx (2nd use) S Stock 21xxx DM
22xxx, 23xxx NDM
24xxx MS
25xxx NDM (de-icing)
In sets fitted with de-icing equipment, the 25xxx car replaces the even-numbered 23xxx car. Eight car units (third digit is 0 or 1) are formed from two four-car 'blocks' in which the last three digits of each car are the same; fifth digit even for A-end cars and odd for D-end cars. Seven car units (third digit is 3, 4 or 5) are the same except the odd-numbered 23xxx is omitted.
4xxxx 1956 40xxx DM (four-car A-end)
41xxx DM (three-car D-end)
42xxx DM (three-car A-end)
43xxx DM (four-car D-end)
44xxx NDM
45xxx T (even in four-car, odd in three-car)
All DM and NDM cars in a unit had same last three digits. All cars were renumbered into 1xxx, 2xxx & 9xxx series when 1959 Stock delivered.
1995 51xxx DM
52xxx T
53xxx UNDM
All cars in a unit had same last three digits.
CO, CP 53xxx DM (A-end)
54xxx DM (D-end)
Ex-O and P Stock; 40000 added to original number.
1992 65xxx DM
67xxx NDM
91xxx DM
92xxx & 93xxx NDM
All cars in a unit had same last three digits; units in 6xxxx series are Waterloo & City line and retain their British Rail numbers.
75xxx Standard Trailers Ex-DT cars; 70000 added to original number.
96xxx 1996 960xx & 961xx DM
962xx & 963xx T
964xx & 965xx UNDM
968xx & 969xx T (fitted with de-icing equipment)
966xx & 967xx ST
All cars in a unit had same last two digits; unit number (1-126) is added to the car type (000=DM, 400=UNDM, 200/600/800=T)

Notes and references


  1. ^ In a number of cases, trains designed for tube lines run on surface routes originally built to mainline standards or for sub-surface trains:
  2. ^ This sometimes proves optimistic, for example the 1992 Stock did not become operational until 1993.
  3. ^ Cars 2752 and 2707 were renumbered to 17000 and 20000 in 1946/1947 for testing as prototypes for A Stock. 17000 was renumbered 17001 following further modifications.



  • Bruce, Graeme (1979) [1968]. Tube Trains Under London (2nd ed.). London Transport. ISBN 0-85329-095-4.
  • Hardy, Brian (1997). "Unit Formations". London Underground Rolling Stock (14th ed.). Capital Transport. ISBN 1-85414-193-7.
  • Hardy, Brian (2002). "Introduction". London Underground Rolling Stock (15th ed.). Capital Transport. ISBN 1-85414-263-1.
  • Hardy, Brian (2002). "Unit Formations". London Underground Rolling Stock (15th ed.). Capital Transport. ISBN 1-85414-263-1.