Southern Railway multiple unit numbering and classification

The Southern Railway created classification and numbering systems for its large fleet of electric multiple units that were perpetuated by the Southern Region of British Rail until the early 1980s, when the impact of TOPS was felt. Even now, some stock have still been allocated Southern-style classifications in a semi-official manner.

Classification

The early AC overhead electric multiple unit types were referred to by a two-letter code. This was adapted for the DC third-rail system that was adopted as standard by the Southern Railway, with unit type being given a three-letter code (sometimes two letters) prefixed by the number of carriages within each unit, e.g. 4SUB for a 4-car suburban set.

The Southern Region of British Rail perpetuated this method of classification, and the same principles were also adopted for diesel-electric multiple unit stock, but with single-letter codes. The last type to be officially allocated a designation in this series was the PEP stock of the early 1970s. However, some types built since then have been given semi-official designations in this style.

NB: This was different from the system used by British Rail (adopted from the LNER) to indicate the type of non-powered coach — see British Rail coach designations.

AC overhead EMUs

DC third rail EMUs

Diesel-electric multiple units

Unit numbering

Unit numbers were allocated in a series commencing from 1001, which followed the set numbers given to semi-fixed formations of hauled coaching stock, 1-1000. Different types of unit were given numbers according to the following division:

This series was perpetuated by the Southern Region of BR, though with modifications, as older set numbers were reused for the following different types:

The 2PEP stock reused number 2001, the 4REP stock reused numbers from 3001 and the 4PEP stock reused numbers 4001/4002. This series was abandoned only in 1983, when units were renumbered to fit in with the TOPS classification system, which had nominally been in use for a decade. Even then, many units only displayed the last four digits of their TOPS number, dropping the first two digits - e.g. unit 412 301 would have the number "2301" applied. Only with later units and the 2xx series DEMUs were the full numbers shown, e.g. Classes 456, 465 and 466, along with some Class 455 sets, carry full 6-digit numbers.

See also

• List of British Rail classes
• British Rail brand names

Notes

References

• British Rail Locomotives and other motive power. London: Ian Allan. 1968. ISBN 0 7110 0008 5.