London Underground rolling stock numbering and classification
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, the Underground Electric Railways Company of London, the District Railway and the Metropolitan Railway. 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 and Metropolitan 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.
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.This system was inaugurated by the London Passenger Transport Board with the 1935 Stock. The large number of broadly similar Tube trains built for the UERL during 1922-1934 were called Standard Stock, although there were many detail differences. They replaced the UERL's original Gate Stock, introduced for the opening of the Bakerloo, Piccadilly and Hampstead 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.
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 StockThis system was commenced by the DR for its stock. When the LPTB was formed, the ex-Metropolitan Railway units were incorporated into this series. By 1960, most letters had been allocated, and the decision was taken to re-issue A to the new Metropolitan stock. 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
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 |
| NDM | Non-Driving Motor car |
| UNDM | Uncoupling Non-Driving Motor car |
| MS | Motor Shunting car |
| T | Trailer car |
| CT | Control Trailer car |
On most lines, the end cars of units are described as 'A' end cars or 'D' end cars. 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, this system cannot apply rigidly.
Car Numbering
Each car carries its own unique number, 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 the LPTB.
- 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 LPTB.
1931 Numbering Series
| Number Series | Car Type | Line Type | Numbers for Inherited Stock | Numbers for New Stock | Numbers for Converted Stock |
| 1-37 | DM | Sub-surface ex-DR | Surviving unrefurbished B Stock | ||
| 1000–1094 | T | Sub-surface ex-DR | Surviving unrefurbished B Stock | ||
| 1700–1717 | CT | Sub-surface ex-DR | Surviving unrefurbished B Stock | ||
| 2000-2999 | DM | Sub-surface ex-MR | 2200-2247 Hammersmith line stock 2500-2769 Main line stock 2900-2940 Northern City line stock | ||
| 3000-3999 | DM | Tube | 3000-3069 and 3282-3688 ex-LER 3912-3999 ex-CLR | 3070-3281 3689-3721 | 3723-3784 DM cars that changed ends |
| 4000-4999 | DM | Sub-surface ex-DR | 4000-4390 and 4591-4645 | 4391-4437 | 4620-4642 ex-CT cars |
| 5000-5999 | CT | Tube | 5000-5359 ex-LER 5928-5999 ex-CLR | ||
| 6000-6199 | CT | Sub-surface ex-DR | 6000-6022 | 6100-6109 ex-DM cars | |
| 6200-6999 | CT | Sub-surface ex-MR | 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 | 7060-7189 | |
| 8000-8999 | T | Sub-surface ex-DR | 8000-8048 Composites 8200-8258 ex-DM cars 8500-8535 8700-8780 ex-DM cars | 8049-8083 Composites 8781-8785 | 8084-8095 Composites, ex-Third class 8786-8799 ex-DM cars 8801-8812 ex-Composites 8813-8848 & 8900-8904 ex-DM cars |
| 9000-9999 | T | Sub-surface ex-MR | 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 |
Notes:
- Ex-MR 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.
- 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-MR ranges First class stock took the lowest numbers, then Composites, then Third class. The LPTB 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
| 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 | All cars in a unit had same last two digits, except double-ended units, which were formed in a series from 854+654+855. |
| 1xxx 2xxx 9xxx | 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. |
| 3xxx 4xxx | 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. |
| 39xx 49xx | 1960 | 39xx DM 49xx T | Fourth digit was even for A-end cars and odd for D-end cars; the original trailers were later replaced by trailers converted from 1938 Stock, whose numbers did not correspond with the DM cars. |
| 5xxx 6xxx | 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. |
| 7xxx 8xxx 17xxx | 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. |
| 10xxx 11xxx 12xxx 30xxx 31xxx 70xxx 90xxx 91xxx 92xxx | 1935, 1938, 1949 | 10xxx DM 11xxx DM 12xxx NDM 30xxx UNDM 31xxx UNDM 70xxx T 90xxx DM 91xxx DM 92xxx NDM | A-end & D-end DM cars had same last three digits; trailer numbers were not matched. |
| 13xxx 14xxx | O & P, Q38 trailers | 13xxx A-end 14xxx D-end | A-end & D-end DM cars had same final three digits, trailer numbers were not matched. |
| 1xxxx | 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 | R | 21xxx DM 22xxx DM 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 | S Stock | 21xxx DM 22xxx, 23xxx NDM 24xxx MS 25xxx NDM | In sets fitted with de-icing equipment, the 25xxx car replaces the even-numbered 23xxx car. Eight car units 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 are the same except the odd-numbered 23xxx is omitted. |
| 4xxxx | 1956 | 40xxx DM 41xxx DM 42xxx DM 43xxx DM 44xxx NDM 45xxx T | 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. |
| 51xxx 52xxx 53xxx | 1995 | 51xxx DM 52xxx T 53xxx UNDM | All cars in a unit had same last three digits. |
| 53xxx 54xxx | CO, CP | 53xxx DM 54xxx DM | Ex-O and P Stock; 40000 added to original number. |
| 65xxx 67xxx 91xxx 92xxx 93xxx | 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 | All cars in a unit had same last two digits. |