London Underground rolling stock numbering and classification

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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.

Electric Multiple Units[edit]

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). The 'Sub-surface' lines are the Circle, District, Hammersmith & City, Metropolitan, and (former) East London lines; all the other lines are 'Tube' lines.

Unit Classification[edit]

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

Tube Stock[edit]

Tube Stock is classified by the year in which it was anticipated at the time of ordering that it would be delivered (this sometimes proves optimistic), e.g. 1992 Stock. This system was commenced by London Underground 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-christend 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 C&SLR's loco+carriage sets, the Watford Joint Stock of the Bakerloo, the GN&CR'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[edit]

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. Q23 Stock. This system was commenced by the DR for its stock. When the London Underground was formed the ex-Metropolitan Railway units were fitted 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' and 'D' respectively, omitting 'B'.

Types of Unit[edit]

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[edit]

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 Bakerloo Line. On lines with a loop at the end that allows trains to turn round (e.g. at Heathrow on the Piccadilly Line, and Kennington on the Northern Line), this system cannot apply rigidly.

Car Numbering[edit]

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:

  • A-end cars have even numbers and D-end cars have odd numbers; cars will usually be renumbered if they are turned to the opposite end. (This principle was applied by the DR and continued by London Underground.)
  • Cars within a unit usually either share the same last two digits, or one end uses the next odd digit after the other end's even digit; frequently when cars are swapped between units they will be renumbered to maintain this approach. (This principle was introduced by the London Underground.)

1931 Numbering Series[edit]

In 1931, the UERL began a major renumbering of all its multiple unit cars. The series was adopted by the London Underground when it took over in 1933 and renumbered stock inherited from other lines into the UERL's series. The table below shows the number ranges used for the inherited stock and initially used by the UERL/London Underground for new stock (including the LU-design 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
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


  • Ex-Metropolitan Railway hauled stock retained their original numbers as they did not conflict with any of the numbers allocated to the multiple unit stock; they were all numbered between 41 and 510 (511-519 were later allocated to cars converted from multiple unit to hauled stock).
  • A 'Composite' car had both First and Third class seating. All Tube stock was Third class only; all ex-DR stock was Third class except those trailers identified as Composite. In the ex-Metropolitan Railway ranges First class stock took the lowest numbers, then Composites, then Thirds. London Underground gradually declassified all stock to Third class, the process being completed in the early years of World War II.
  • Some cars converted to Trailers after 1935 carried a '0' prefix to their numbers, as was applied to new-build trailer cars in this period. In some cases, such cars briefly retained their original DM numbers but with a '0' prefix before being renumbered into the appropriate range for trailers.

Later Developments[edit]

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)
All cars in a unit had same last two digits.


  • 17000 and 20000 were used for cars converted from T Stock in 1946/1947 as prototypes for A Stock. 17000 was renumbered 17001 following further modifications.


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