British Rail locomotive and multiple unit numbering and classification
Encyclopedia
A number of different numbering and classification schemes were used for locomotives and multiple units operated by British Rail
ways (BR), and this page explains the principal systems. This section also covers the post-privatisation period, as the broad numbering and classification arrangements have not altered since the break-up of BR.
Locomotives and multiple units (the majority being self-propelled) have frequently had similar arrangements for classification and numbering, so are considered together here. There are also links to other pages that deal in greater depth with the particulars of individual types.
In the main, new locomotives and multiple units built by BR to pre-nationalisation designs were numbered and classified according to the principles applied by the relevant 'Big Four' company.
In order to remove the duplications of locomotive numbers, all locomotives were placed into a new number series as follows:
Note: *Isle of Wight locomotives retained their existing numbers in a separate series commencing at W1, and locomotives transferred to the island by BR were renumbered into that series - and vice versa for those returned to the mainland.
This approach meant that the numbering arrangements adopted by the pre-Nationalisation companies were retained in the new system, and new locomotives built to the designs of the old companies were numbered appropriately in their series. Locomotives inherited from smaller concerns were numbered in the most appropriate regional list, e.g. ex-East Kent Railway
stock utilised blank numbers in the 3xxxx ex-SR series.
The new series for diesel, petrol, gas and electric locomotives were arranged as follows:
Note: * Number 13000 was initially allocated to a 250 hp (186 kW) ex-LMS shunter, but this locomotive was withdrawn before being renumbered.
s was undertaken on a regional basis, with each region having its own series commencing from 001. Most diesel multiple unit
s were not allocated unit numbers, though in later years numbers were allocated on a regional basis in the Scottish and Western regions, and by individual depots elsewhere. For more details on these series, see British Rail Regional Multiple Unit Numbering
.
To classify electric stock, a two-letter prefix was used to indicate what type it was, followed by a number issued sequentially from 1. This was a system adapted from that used by the LNER for its electric stock (e.g. EM1, see here). The additional prefixes used were:
The Eastern and North Eastern Regions used a series of different classifications for diesel locomotives. The first method was also adapted from the old LNER system, and applied only to diesel shunters operating on those regions. It comprised a prefix, indicating the transmission type and wheel arrangement, followed by a number allocated sequentially from 1. The prefixes used were:
The second classification system was developed in 1955 and applied to all types then in existence on British Rail. It was based on the format Dx/y, where x was the power of the locomotive in hundreds of horsepower and y was a number allocated sequentially to specific types (e.g. D1/1 would be a shunter with a 100 to 199 hp (75 to 148 kW) rating, D33/1 would be a Type 5 locomotive). The series was extensively re-arranged in 1962 in a somewhat confusing way, but following the same basic principles.
The Southern Region followed existing numbering (for its multiple unit
s) and classification systems (for both multiple units and locomotives) inherited from the SR. The EMU classification system (e.g. 4SUB, see here
) system was also extended to include their diesel-electric multiple units, but with a single letter. Locomotives were given a two-letter code, with the second letter indicating detail differences within the main type. For instance, what were to become Class 33 locomotives from 1973, were Class KA or KB depending on whether they were the standard design or that fitted for push-pull working with 4TC units.
The 1955 Modernisation Plan heralded big changes in this situation, and from 1957 a new numbering system was used for diesel and electric locomotives ordered by British Railways, including those shunters ordered before 1957, which were renumbered into the new system. All steam and gas-turbine locomotives, and diesel and electric locomotives built to pre-nationalisation orders retained their existing numbers under the 1948 arrangements, though some had a 'D' or 'E' prefix added to their number in error.
Of the shunters that were renumbered, the only transparent renumbering was for those that had been numbered in the 13xxx series, for which the '1' was simply replaced with a 'D'. All the others were completely renumbered to separate out the different classes.
As always, there were some oddities. The 650 hp diesel hydraulic locomotives later Class 14 were numbered from D9500 upwards. When the Type 2 series got too crowded later on, new Sulzer Type 2 locomotives (later British Rail Class 25
) were numbered from D7500 upwards. Some experimental locomotives carried D0xxx numbers.
When the last mainline steam locomotive was withdrawn in August 1968 (leaving only three on the self-contained narrow gauge Vale of Rheidol Railway
), the 'D' prefix was dropped.
s, with a diesel generator for working off electrified lines, were numbered from E6000 upwards.
For AC locomotives, the first number was to be an indication of power. For example, if the power was in the range 2000 to 2999 hp, it would be numbered between E2000-E2999, and so on. In fact, apart from E2001 (the prototype AC locomotive, converted from a gas turbine locomotive, later Class 80), all AC locomotives were numbered from E3001 upwards. When new 5000 hp locomotives were under construction (later Class 87), these were allocated numbers from E3201 upwards, though they never carried these numbers as the 1973 arrangements were already in place by the time the first one was built.
(TOPS), a computerised system developed by the Southern Pacific Railroad
in the United States. All types of locomotive and multiple unit received a TOPS classification, according to this broad division:
From 1973, British Railways started to apply new numbers to locomotives and multiple units based on the TOPS classification system. The format of these numbers is xxxyyy, where xxx is the class number and yyy the unique identifier for that locomotive or unit. All locomotive classes have unique identifiers that commence at xx001, except classes 43 (originally treated as multiple unit carriages), 97 and 98 (departmental and steam locomotives). Multiple unit classes are treated differently, because an attempt has been made to give units working within the same region or sector unique identifiers (for more information see British Rail Regional Multiple Unit Numbering
). In recent years, unit numbers have also been tied in with the numbers of the carriages within a unit (e.g. 150201 is formed of carriages 52201 and 57201). As a result, very few multiple unit classes commence from xxx001.
Where there are variations within a class, subclasses are used in the format xxx/y. Usually, the subclass is connected to the first digit of the unique identfier, so that the first locomotive in subclass 47/3 was 47301. However, some caution is required on this point for the following reasons:
So far as renumbering from the 1957 arrangements was concerned, most locomotives retained the last two digits of their number, though some classes were renumbered without reference to their previous numbers. This was usually where sub-classes had already been or were in the process of being created (for example Classes 45 and 47), but some classes were renumbered randomly for no apparent reason (for example Class 86). The other exception was the first locomotive of each class, which had usually carried Dxx00 numbers under the 1957 arrangements, since TOPS could not handle numbers ending in '000'. These were often renumbered to the end of the class (e.g. D400 became 50050), or took the number of another class member that had already been withdrawn (e.g. D5000 became 24005).
The situation was different for multiple units. Where unit numbers were carried, they were usually three-digit already. TOPS simply prefixed these existing unit numbers with the newly-allocated TOPS class number. The process was more complicated on the Southern Region, which used four-digit unit numbers and where a more general unit renumbering was required so that the first number of the unit coincided with the last digit of the class number. Many diesel multiple units were not kept in regular formations, so did not have existing unit numbers, and this situation was not changed under TOPS (except following refurbishment).
The TOPS system has been perpetuated by the privatised railway, though the allocation of classes and numbers appears to have become more random and less governed by the rules followed by British Railways (but even they made exceptions). See British Carriage and Wagon Numbering and Classification
for an explanation of how TOPS applied also to carriages and wagons.
Please Note: This section explains the successful application of TOPS
to multiple unit stock, the arrangement that persists today. However, there was an earlier attempt to apply TOPS that differed from the arrangement set out below. More details about the first arrangement may be found here
.
The following table shows in more detail how the classification of diesel locomotives was overlaid on the 1957 classification by Type:
AC electric locomotive classes AL1 to AL6 became 81-86 in order.
AC electric multiple units AM1-AM11 became 301-311 in order (in fact the AM1 units had already been withdrawn, so Class 301 was never actually used). The 1xx and 2xx series were originally arranged so that driving motors, driving trailers and trailer cars all had their own individual class numbers (presumably because these units were more prone to being reformed), but this was subsequently revised so that each type of unit had a single class number, as allocated to the driving motor car.
Whereas within most ranges class numbers were allocated sequentially as new types were constructed, the Southern Region adopted a more complicated system for their electric multiple units, with the second and third digits indicating in more detail the type of unit. Second digits were allocated as follows:
Third digits were allocated as follows:
Of course, many exceptions arose over time. One major change was to change the classification of unpowered trailer units from 49x numbers to 4x8 numbers (which involved reclassifying Class 491 to Class 438). When Southern Region unit numbers were changed to fit with the TOPS classification system, former 4x0 classes were all reclassified to 4x2. This was necessary because Southern Region units only displayed the last four digits of their six-digit TOPS number, and it was decided that no painted unit number should commence with a '0'. It is worth noting that despite only showing the last four digits, the actual number of the unit was still the six-digit TOPS number. This often causes confusion both to enthusiasts and those outside the field alike.
Related pages on BR numbering and classification include:
British Rail
British Railways , which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages...
ways (BR), and this page explains the principal systems. This section also covers the post-privatisation period, as the broad numbering and classification arrangements have not altered since the break-up of BR.
Locomotives and multiple units (the majority being self-propelled) have frequently had similar arrangements for classification and numbering, so are considered together here. There are also links to other pages that deal in greater depth with the particulars of individual types.
Constituent companies
In 1948, BR inherited a variety of locomotives and multiple units from the 'Big Four' railway companies and some smaller concerns. Details of the numbering and classification systems used by the 'Big Four' companies are covered in the following pages:- Great Western RailwayGreat Western RailwayThe Great Western Railway was a British railway company that linked London with the south-west and west of England and most of Wales. It was founded in 1833, received its enabling Act of Parliament in 1835 and ran its first trains in 1838...
: GWR locomotive numbering and classificationGWR locomotive numbering and classificationThe GWR was the longest-lived of the pre-nationalisation railway companies in Britain, surviving the 'Grouping' of the railways in 1923 almost unchanged. As a result, the history of its numbering and classification of locomotives is relatively complicated... - Southern Railway: SR locomotive numbering and classificationSR locomotive numbering and classificationA number of different numbering and classification schemes were used for the locomotives owned by the Southern Railway and its constituent companies...
and SR multiple unit numbering and classificationSR multiple unit numbering and classificationThe 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... - London, Midland and Scottish RailwayLondon, Midland and Scottish RailwayThe London Midland and Scottish Railway was a British railway company. It was formed on 1 January 1923 under the Railways Act of 1921, which required the grouping of over 120 separate railway companies into just four...
: LMS locomotive numbering and classificationLMS locomotive numbering and classificationA number of different numbering and classification schemes were used for the locomotives owned by the London, Midland and Scottish Railway and its constituent companies; this page explains the principal systems that were used.... - London and North Eastern RailwayLondon and North Eastern RailwayThe London and North Eastern Railway was the second-largest of the "Big Four" railway companies created by the Railways Act 1921 in Britain...
: LNER locomotive numbering and classificationLNER locomotive numbering and classificationA number of different numbering and classification schemes were used for the locomotives owned by the London and North Eastern Railway and its constituent companies. This page explains the principal systems that were used...
In the main, new locomotives and multiple units built by BR to pre-nationalisation designs were numbered and classified according to the principles applied by the relevant 'Big Four' company.
1948 numbering and classification
Immediately after nationalisation, BR had to decide how to number and classify the stock it had inherited from the 'Big Four' companies, and how newly-built stock would be included. In the main, it decided to simply adapt what was already there.Locomotives
The classification systems of the 'Big Four' were left unchanged for the inherited locomotives. However, BR decided to adopt the LMS power classification system as its preferred model and all inherited locomotives received a classification in this series as well as their traditional classification.In order to remove the duplications of locomotive numbers, all locomotives were placed into a new number series as follows:
| Range | Description | Renumbering |
|---|---|---|
| 1-9999 | Ex-GWR steam locomotives | Numbers unchanged |
| 10000-19999 | Diesel and gas turbine locomotives | Without reference to previous number, except pioneer mainline locos LMS 10000/10001, whose numbers were unchanged |
| 20000-29999 | Electric locomotives | SR CC1-3 to 20001-3, LNER 6000 to 26000, others without reference to previous number |
| 30000-39999 | Ex-SR steam locomotives (except Isle of Wight*) | Addition of 30000, except: C1 etc to 33xxx, 21C101 etc to 34xxx, 21C1 etc to 35xxx, 3xxx series renumbered without reference to previous number |
| 40000-59999 | Ex-LMS steam locomotives | Addition of 40000, except 2xxxx series renumbered without reference to previous number into the 58xxx series |
| 60000-69999 | Ex-LNER steam locomotives | Addition of 60000, except 10000 to 60700 |
| 70000-79999 | BR-design tender steam locomotives | New Build |
| 80000-89999 | BR-design tank steam locomotives | New Build |
| 90000-99999 | BR & War Department large freight locomotives | ex-War Department locos renumbered without reference to previous number |
Note: *Isle of Wight locomotives retained their existing numbers in a separate series commencing at W1, and locomotives transferred to the island by BR were renumbered into that series - and vice versa for those returned to the mainland.
This approach meant that the numbering arrangements adopted by the pre-Nationalisation companies were retained in the new system, and new locomotives built to the designs of the old companies were numbered appropriately in their series. Locomotives inherited from smaller concerns were numbered in the most appropriate regional list, e.g. ex-East Kent Railway
East Kent Railway
The East Kent Railway was an early railway operating between Strood and the town of Faversham in Kent England, during 1858 and 1859. In the latter year it changed its name to the London, Chatham and Dover Railway to reflect its ambitions to build a rival line from London to Dover via Chatham and...
stock utilised blank numbers in the 3xxxx ex-SR series.
The new series for diesel, petrol, gas and electric locomotives were arranged as follows:
| Range | Description |
|---|---|
| 10xxx | Mainline diesel Locomotives |
| 11xxx | Diesel mechanical & diesel hydraulic shunters (British Railways orders) |
| 12xxx | Ex-LMS shunters 300 hp (224 kW) and over |
| 13xxx | Diesel electric shunters (British Railways orders) * |
| 150xx | Ex-LNER shunters |
| 151xx | Ex-GWR shunters |
| 152xx | Ex-SR shunters |
| 18xxx | Gas turbine locomotives |
| 20xxx | Ex-SR electric locomotives |
| 26xxx | Ex-LNER electric locomotives |
Note: * Number 13000 was initially allocated to a 250 hp (186 kW) ex-LMS shunter, but this locomotive was withdrawn before being renumbered.
Modern traction
Numbering of electric multiple unitElectric multiple unit
An electric multiple unit or EMU is a multiple unit train consisting of self-propelled carriages, using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a number of the carriages...
s was undertaken on a regional basis, with each region having its own series commencing from 001. Most diesel multiple unit
Diesel multiple unit
A diesel multiple unit or DMU is a multiple unit train consisting of multiple carriages powered by one or more on-board diesel engines. They may also be referred to as a railcar or railmotor, depending on country.-Design:...
s were not allocated unit numbers, though in later years numbers were allocated on a regional basis in the Scottish and Western regions, and by individual depots elsewhere. For more details on these series, see British Rail Regional Multiple Unit Numbering
British Rail regional multiple unit numbering
Prior to the introduction of TOPS, electric multiple unit numbers were allocated by the British Rail regions in their own series. Diesel multiple units did not carry unit numbers at first, but the Scottish and Western Regions later adopted their own series for these units, whilst elsewhere...
.
To classify electric stock, a two-letter prefix was used to indicate what type it was, followed by a number issued sequentially from 1. This was a system adapted from that used by the LNER for its electric stock (e.g. EM1, see here). The additional prefixes used were:
- AL: AC electric locomotive
- AM: AC electric multiple unit
The Eastern and North Eastern Regions used a series of different classifications for diesel locomotives. The first method was also adapted from the old LNER system, and applied only to diesel shunters operating on those regions. It comprised a prefix, indicating the transmission type and wheel arrangement, followed by a number allocated sequentially from 1. The prefixes used were:
- DEJ: Diesel-electric, 0-6-0 wheel arrangement
- DJ: Diesel-mechanical or hydraulic, 0-6-0 wheel arrangement
- DY: Diesel-mechanical or hydraulic, 0-4-0 wheel arrangement
The second classification system was developed in 1955 and applied to all types then in existence on British Rail. It was based on the format Dx/y, where x was the power of the locomotive in hundreds of horsepower and y was a number allocated sequentially to specific types (e.g. D1/1 would be a shunter with a 100 to 199 hp (75 to 148 kW) rating, D33/1 would be a Type 5 locomotive). The series was extensively re-arranged in 1962 in a somewhat confusing way, but following the same basic principles.
The Southern Region followed existing numbering (for its multiple unit
Multiple unit
The term multiple unit or MU is used to describe a self-propelled carriages capable of coupling with other units of the same or similar type and still being controlled from one driving cab. The term is commonly used to denote passenger trainsets consisting of more than one carriage...
s) and classification systems (for both multiple units and locomotives) inherited from the SR. The EMU classification system (e.g. 4SUB, see here
SR 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...
) system was also extended to include their diesel-electric multiple units, but with a single letter. Locomotives were given a two-letter code, with the second letter indicating detail differences within the main type. For instance, what were to become Class 33 locomotives from 1973, were Class KA or KB depending on whether they were the standard design or that fitted for push-pull working with 4TC units.
1957 numbering and classification
In the early period of British Railways, steam locomotion had continued to be of prime importance. Apart from a growing selection of diesel shunters, there had been almost no development of mainline diesel or electric traction beyond the few locomotives ordered by the 'Big Four' companies.The 1955 Modernisation Plan heralded big changes in this situation, and from 1957 a new numbering system was used for diesel and electric locomotives ordered by British Railways, including those shunters ordered before 1957, which were renumbered into the new system. All steam and gas-turbine locomotives, and diesel and electric locomotives built to pre-nationalisation orders retained their existing numbers under the 1948 arrangements, though some had a 'D' or 'E' prefix added to their number in error.
Diesel locomotives
The numbering system matched up the new 'Type' classification that had been adopted for diesel traction, and which was based on the power of the locomotive. The broad categories were as follows:| Range | Type | Engine power |
|---|---|---|
| D1-D1999 | Type 4 | 2000 to 2999 hp |
| D2000-D2999 | Shunters | Under 300 hp |
| D3000-D4999 | Shunters | 300 to 799 hp |
| D5000-D6499 | Type 2 | 1001 to 1499 hp |
| D6500-D7999 | Type 3 | 1500 to 1999 hp |
| D8000-D8999 | Type 1 | 800 to 1000 hp |
| D9000-D9999 | Type 5 | Over 3000 hp |
Of the shunters that were renumbered, the only transparent renumbering was for those that had been numbered in the 13xxx series, for which the '1' was simply replaced with a 'D'. All the others were completely renumbered to separate out the different classes.
As always, there were some oddities. The 650 hp diesel hydraulic locomotives later Class 14 were numbered from D9500 upwards. When the Type 2 series got too crowded later on, new Sulzer Type 2 locomotives (later British Rail Class 25
British Rail Class 25
The British Rail Class 25 diesel locomotives were also known as Sulzer Type 2 and nicknamed Rats, as it was alleged they could be seen everywhere in Britain, and hence were "as common as rats"...
) were numbered from D7500 upwards. Some experimental locomotives carried D0xxx numbers.
When the last mainline steam locomotive was withdrawn in August 1968 (leaving only three on the self-contained narrow gauge Vale of Rheidol Railway
Vale of Rheidol Railway
The Vale of Rheidol Railway is a narrow-gauge gauge heritage railway that runs for between Aberystwyth and Devil's Bridge in the county of Ceredigion, Wales...
), the 'D' prefix was dropped.
Electric locomotives
The numbering system was divided into two series, one for AC locomotives and one for DC locomotives. DC locomotives were numbered from E5000 upwards, and DC electro-diesel locomotiveElectro-diesel locomotive
An Electro-diesel locomotive is powered either from an electricity supply or by using the onboard diesel engine...
s, with a diesel generator for working off electrified lines, were numbered from E6000 upwards.
For AC locomotives, the first number was to be an indication of power. For example, if the power was in the range 2000 to 2999 hp, it would be numbered between E2000-E2999, and so on. In fact, apart from E2001 (the prototype AC locomotive, converted from a gas turbine locomotive, later Class 80), all AC locomotives were numbered from E3001 upwards. When new 5000 hp locomotives were under construction (later Class 87), these were allocated numbers from E3201 upwards, though they never carried these numbers as the 1973 arrangements were already in place by the time the first one was built.
1973 numbering and classification - TOPS
At the end of the 1960s, British Railways adopted the Total Operations Processing SystemTOPS
Total Operations Processing System, or TOPS, is a computer system for managing the locomotives and rolling stock owned by a rail system...
(TOPS), a computerised system developed by the Southern Pacific Railroad
Southern Pacific Railroad
The Southern Pacific Transportation Company , earlier Southern Pacific Railroad and Southern Pacific Company, and usually simply called the Southern Pacific or Espee, was an American railroad....
in the United States. All types of locomotive and multiple unit received a TOPS classification, according to this broad division:
| Class | Allocation |
|---|---|
| (0)xx | Locomotives and Ships (leading zero was ignored) |
| 1xx | Diesel-Mechanical (including hydraulic) Multiple Units |
| 2xx | Diesel-Electric Multiple Units |
| 3xx | AC and Multi-Voltage Electric Multiple Units |
| 4xx | Southern Region DC Electric Multiple Units |
| 5xx | Other DC Electric Multiple Units |
| 9xx | Departmental (non-revenue earning) Multiple Units |
From 1973, British Railways started to apply new numbers to locomotives and multiple units based on the TOPS classification system. The format of these numbers is xxxyyy, where xxx is the class number and yyy the unique identifier for that locomotive or unit. All locomotive classes have unique identifiers that commence at xx001, except classes 43 (originally treated as multiple unit carriages), 97 and 98 (departmental and steam locomotives). Multiple unit classes are treated differently, because an attempt has been made to give units working within the same region or sector unique identifiers (for more information see British Rail Regional Multiple Unit Numbering
British Rail regional multiple unit numbering
Prior to the introduction of TOPS, electric multiple unit numbers were allocated by the British Rail regions in their own series. Diesel multiple units did not carry unit numbers at first, but the Scottish and Western Regions later adopted their own series for these units, whilst elsewhere...
). In recent years, unit numbers have also been tied in with the numbers of the carriages within a unit (e.g. 150201 is formed of carriages 52201 and 57201). As a result, very few multiple unit classes commence from xxx001.
Where there are variations within a class, subclasses are used in the format xxx/y. Usually, the subclass is connected to the first digit of the unique identfier, so that the first locomotive in subclass 47/3 was 47301. However, some caution is required on this point for the following reasons:
- Where there are more than 100 examples in a subclass the identifier becomes obscured, e.g. 31201 is in subclass 31/1, which runs from 31101 to 31327.
- Some classes renumbered from the 1957 arrangements simply had consecutive numbers from xx001, which ignored the subclasses identified, e.g. 25033 was in subclass 25/1.
- Where numbers within a class became congested, it wasn't always possible to make the connection, e.g. locomotives in subclass 47/2 were numbered downwards from 47399. In other cases it wasn't possible to start from xxxy01, e.g. subclass 08/9 started from 08991 because subclass 08/0 ran from 08001 to 08958.
- Because of the different arrangements for numbering multiple units (see above), subclasses may have no link to the unique identifier at all; this is especially true on the Southern Region. Sometimes, where there is a principal run of units and a small variant subclass, the majority will be subclass xxx/0 whatever their identifier, but the variant's subclass does reflect the identifier, e.g. Subclass 302/0 for the standard passenger units (302201-312) and 302/9 for the postal units (302990-302993).
So far as renumbering from the 1957 arrangements was concerned, most locomotives retained the last two digits of their number, though some classes were renumbered without reference to their previous numbers. This was usually where sub-classes had already been or were in the process of being created (for example Classes 45 and 47), but some classes were renumbered randomly for no apparent reason (for example Class 86). The other exception was the first locomotive of each class, which had usually carried Dxx00 numbers under the 1957 arrangements, since TOPS could not handle numbers ending in '000'. These were often renumbered to the end of the class (e.g. D400 became 50050), or took the number of another class member that had already been withdrawn (e.g. D5000 became 24005).
The situation was different for multiple units. Where unit numbers were carried, they were usually three-digit already. TOPS simply prefixed these existing unit numbers with the newly-allocated TOPS class number. The process was more complicated on the Southern Region, which used four-digit unit numbers and where a more general unit renumbering was required so that the first number of the unit coincided with the last digit of the class number. Many diesel multiple units were not kept in regular formations, so did not have existing unit numbers, and this situation was not changed under TOPS (except following refurbishment).
The TOPS system has been perpetuated by the privatised railway, though the allocation of classes and numbers appears to have become more random and less governed by the rules followed by British Railways (but even they made exceptions). See British Carriage and Wagon Numbering and Classification
British carriage and wagon numbering and classification
A number of different numbering and classification schemes have been used for carriages and wagons on Britain's railways, and this page explains the principal systems...
for an explanation of how TOPS applied also to carriages and wagons.
Please Note: This section explains the successful application of TOPS
TOPS
Total Operations Processing System, or TOPS, is a computer system for managing the locomotives and rolling stock owned by a rail system...
to multiple unit stock, the arrangement that persists today. However, there was an earlier attempt to apply TOPS that differed from the arrangement set out below. More details about the first arrangement may be found here
British Rail TOPS first arrangement
At the end of the 1960s, British Railways adopted the Total Operations Processing System , a computerised system developed by the Southern Pacific Railroad in the United States. All types of locomotive and multiple unit received a TOPS classification, but the first attempt at applying TOPS was soon...
.
Locomotives
The series of locomotive classes were allocated according to the following pattern:| Class | Allocation |
|---|---|
| 01-69 | Diesel locomotives (Excluding Class 70 British Rail Class 70 (diesel) The General Electric PowerHaul is a type of six axle Co-Co mainline freight locomotive manufactured by General Electric in Erie, Pennsylvania, and also assembled under licence by Tulomsas of Turkey and to be produced by UGL Limited in Australia.... ) |
| 70-79 | DC electric and electro-diesel locomotives |
| 80-96 | AC and multi-voltage electric locomotives |
| 97 | Departmental (non-revenue earning) locomotives |
| 98 | Steam locomotives |
| 99 | Ships |
The following table shows in more detail how the classification of diesel locomotives was overlaid on the 1957 classification by Type:
| Class | Type | Horsepower Horsepower Horsepower is the name of several units of measurement of power. The most common definitions equal between 735.5 and 750 watts.Horsepower was originally defined to compare the output of steam engines with the power of draft horses in continuous operation. The unit was widely adopted to measure the... |
Previous number range |
|---|---|---|---|
| 01-07 | Shunters | Under 300 | D2000-D2999 |
| 08-14 | Shunters | 300 – 799 | D3000-D4999/D9500-D9999 |
| 15-20 | Type 1 | 800 – 1000 | D8000-D8999 |
| 21-32 | Type 2 | 1001 – 1499 | D5000-D6499/D7500-D7999 |
| 33-39 | Type 3 | 1500 – 1999 | D6500-D7499 |
| 40-54 | Type 4 | 2000 – 2999 | D1-D1999 |
| 55-69 | Type 5 | Over 3000 | D9000-D9499 |
AC electric locomotive classes AL1 to AL6 became 81-86 in order.
Multiple units
The multiple unit series were divided up as follows:| Class | Type | |
|---|---|---|
| 100-114 | Diesel-Mechanical | 'Low Density' passenger units (i.e. few doors per carriage) - mostly short (57'0") frame, but Class 114 are long |
| 115-127 | Mixture of 'High Density' (i.e. doors to every seating bay) and 'Cross-Country' (long distance) passenger units - long (63'6") frame | |
| 128-131 | Parcels units - mostly long frame, but Class 129 are short | |
| 140-144 | Second generation railbus (4-wheel) units ('Pacer') | |
| 150-199 | Second generation bogie units ('Sprinter', 'Networker', 'Turbostar', 'Coradia') | |
| 200-207 | Diesel-Electric | First generation units |
| 210-249 | Second generation units | |
| 250-299 | Express units | |
| 300-312 | AC Electric | First generation units |
| 313-369 | Second generation units | |
| 370-399 | Express units (since the privatisation of British Rail Privatisation of British Rail The privatisation of British Rail was set in motion when the Conservative government enacted, on 19 January 1993, the British Coal and British Rail Act 1993 . This enabled the relevant Secretary of State to issue directions to the relevant Board... , this series has included other second generation units) |
|
| 920-935 | Departmental units | Southern Region departmental units |
| 936-939 | Other departmental electric multiple units | |
| 950-960 | Other departmental diesel multiple units (since the privatisation of British Rail, this series has included electric multiple units) |
AC electric multiple units AM1-AM11 became 301-311 in order (in fact the AM1 units had already been withdrawn, so Class 301 was never actually used). The 1xx and 2xx series were originally arranged so that driving motors, driving trailers and trailer cars all had their own individual class numbers (presumably because these units were more prone to being reformed), but this was subsequently revised so that each type of unit had a single class number, as allocated to the driving motor car.
Whereas within most ranges class numbers were allocated sequentially as new types were constructed, the Southern Region adopted a more complicated system for their electric multiple units, with the second and third digits indicating in more detail the type of unit. Second digits were allocated as follows:
| Class | Type |
|---|---|
| 40x | Southern Railway-designed units |
| 41x | 1950s British Railways-designed units |
| 42x | 1960s British Railways-designed units |
| 43x | 1967 Bournemouth Electrification units |
| 44x | 1970s British Railways-designed units |
| 45x | 1980s British Railways-designed units |
| 46x | 1990s Networker units |
| 48x | Underground ('Tube'-sized) units (also temporary formations and, later, 'Gatwick Express' units) |
| 49x | Unpowered trailer units (later 4x8) |
Third digits were allocated as follows:
| Class | Type |
|---|---|
| 4x0 | Express units with buffet (later 4x2) |
| 4x1 | Express units |
| 4x3 | Four-car outer-suburban units |
| 4x4 | Two-car outer-suburban units |
| 4x5 | Four-car inner-suburban units |
| 4x6 | Two/three-car inner-suburban units |
| 4x7 | Special purpose units (e.g. first 'Gatwick Express' units) |
| 4x9 | Single car units |
Of course, many exceptions arose over time. One major change was to change the classification of unpowered trailer units from 49x numbers to 4x8 numbers (which involved reclassifying Class 491 to Class 438). When Southern Region unit numbers were changed to fit with the TOPS classification system, former 4x0 classes were all reclassified to 4x2. This was necessary because Southern Region units only displayed the last four digits of their six-digit TOPS number, and it was decided that no painted unit number should commence with a '0'. It is worth noting that despite only showing the last four digits, the actual number of the unit was still the six-digit TOPS number. This often causes confusion both to enthusiasts and those outside the field alike.
See also
For further information on individual classes of locomotive or multiple unit, see these pages:- List of Non-steam British Rail classes
- Steam locomotives of British RailwaysSteam locomotives of British RailwaysThe steam locomotives of British Railways were used by British Railways over the period 1948–1968. The vast majority of these were inherited from its four constituent companies, the "Big Four"....
- Locomotives of the Great Western RailwayLocomotives of the Great Western RailwayThe first Locomotives of the Great Western Railway were specified by Isambard Kingdom Brunel but Daniel Gooch was soon appointed as the railway's Locomotive Superintendent. He designed several different broad gauge types for the growing railway, such as the Firefly and later Iron Duke Class 2-2-2s...
- Locomotives of the Southern RailwayLocomotives of the Southern RailwayThe Southern Railway took a key role in expanding the 660 V DC third rail electrified network begun by the London & South Western Railway. As a result of this, and its smaller operating area, its steam locomotive stock was the smallest of the 'Big Four' companies. Yet its locomotives were unique...
- Locomotives of the London, Midland and Scottish RailwayLocomotives of the London, Midland and Scottish RailwayThe London, Midland and Scottish Railway had the largest stock of steam locomotives of any of the 'Big Four' Grouping, ie pre-Nationalisation railway companies in thec UK. Despite early troubles arising from factions within the new company, the LMS went on to build some very successful designs;...
- Locomotives of the London and North Eastern RailwayLocomotives of the London and North Eastern RailwayThe London and North Eastern Railway produced several classes of locomotive, mostly to the designs of Nigel Gresley, characterised by a three cylinder layout with a parallel boiler and round-topped firebox. It produced the most iconic locomotive of its day, 4468 'Mallard', the holder of the...
- British diesel and electric multiple unitsBritish diesel and electric multiple units'Multiple Unit' is a term used to describe a train which does not have a separate locomotive. Typically these are passenger trains with accommodation in every vehicle and motors or engines distributed under the floor along the length of the train...
Related pages on BR numbering and classification include:
- British Rail TOPS first arrangementBritish Rail TOPS first arrangementAt the end of the 1960s, British Railways adopted the Total Operations Processing System , a computerised system developed by the Southern Pacific Railroad in the United States. All types of locomotive and multiple unit received a TOPS classification, but the first attempt at applying TOPS was soon...
- British Rail Regional Multiple Unit NumberingBritish Rail regional multiple unit numberingPrior to the introduction of TOPS, electric multiple unit numbers were allocated by the British Rail regions in their own series. Diesel multiple units did not carry unit numbers at first, but the Scottish and Western Regions later adopted their own series for these units, whilst elsewhere...
- British Carriage and Wagon Numbering and ClassificationBritish carriage and wagon numbering and classificationA number of different numbering and classification schemes have been used for carriages and wagons on Britain's railways, and this page explains the principal systems...
- Route availabilityRoute availabilityRoute Availability is the system by which the permanent way and supporting works of the National Rail network of Great Britain are graded. All routes are allocated an RA number between 1 and 10....