Train reporting number

A train reporting number in Great Britain identifies a particular train service. It consists of:
The train reporting number is often called the headcode, a throwback to when the number was physically displayed at the head of a train.
History.
Headcodes.
Headcodes were introduced around 1850 and were shown by oil lamps facing forward on the front of the locomotive. The position of these lamps on the locomotive denoted the class of train, which assisted the signalmen to determine the gaps between trains required in the interval-based signalling system that was used at the time. The lamps were lit at night and were usually painted white to assist with sighting by day. On some lines white discs were used by day in the place of lamps.
With the coming of absolute block signalling, the class-based headcodes allowed signallers to identify and regulate trains properly. However on some busy lines, particularly busy suburban ones, the headcode denoted the route of the train rather than the class of train. In these areas junctions were complex and timetables were intense: it was more important that signallers routed the trains correctly than regulated trains by class. This was prevalent in the south of England, where companies used six headlamp positions to show the route of train.
Some companies had their own code format which led to some confusion where trains from one company ran onto other companies' lines. The Railway Clearing House intervened to standardise headcodes, based on four lamp positions, and they were adopted by the majority of lines outside the south of England. At the time of the 1923 Grouping, the standard headcodes were simplified so that normally only two lamps were used at any one time, and these codes were adopted by the London Midland and Scottish Railway, the Great Western Railway (GWR) and the London and North Eastern Railway. The Southern Railway (SR) retained a route-based headcode system, with up to four lamps in six positions. Notable exceptions were former Glasgow and South Western Railway and the Somerset and Dorset Joint Railway lines, which continued with their own headcodes on internal trains. The Caledonian Railway maintained a completely different route-based headcode system consisting of a pair of semaphore arms mounted on the locomotive - the angle of the two arms and their position (on the buffer beam or smokebox) indicated the routing.
Train reporting numbers.
Historically train reporting numbers were used to denote trains in the internal working timetable. These contained one or more letters or numbers to either uniquely identify a particular train, or denote its route (particularly on busier lines). Not all lines used these and the details and extent of the practice varied widely between companies. Although these numbers were in many places confined to timetables and other documentation, in some busier areas they were actually shown at the head of the train.
On the SR, a single alphabetic character system of denoting routes used on suburban lines grew into a two character route-based system. This was developed at the same time as a significant programme of electrification and the consequent introduction of a large number of multiple unit trains. Many of these trains were fitted with display devices to show the route code instead of a lamp or disc-based headcode. Originally this was a back-lit stencil with the single letter code, later a two-character roller-blind system was used. The code system had equivalence with the lamp or disc route-based headcodes in assisting signallers with routing trains.
On the other railways, the reporting number was on occasion displayed at the head of the train along with the lamp headcode. This happened more often than not with special trains or other unusual trains (e.g. summer Saturday timetables), to allow signallers to identify unfamiliar trains and route them correctly. This code was sometimes either chalked onto the locomotive front or pasted as paper characters onto a headcode disc. The GWR sometimes used a three-character frame mounted on the locomotive smokebox in which the train reporting number could be displayed.
After nationalisation, British Railways continued with these headcodes and the new diesel and electric locomotives and multiple units were built either with a disc/lamp system (now powered by electricity) or a two to four character roller-blind display system depending on what part of the network they were to work.
1960 headcode/reporting number merger.
In 1960, the current format was introduced where train class, route and reporting number information are combined in four characters. All diesel and electric locomotives and multiple units built after that date were fitted with a roller-blind display that could display the full reporting number, except locomotives and multiple units destined for the Southern Region, which continued its long-standing practice of two-character alpha-numeric displays.
By 1976, the replacement of the huge number of manual signal boxes with centralised power-signalling coupled with computer-based train control and more modern telecommunications systems meant that it was no longer necessary to display headcodes throughout the railway network. Outside the Southern Region blinds were set to "00" or "0000", and discs/lamps to the former express passenger code. Roller blinds were later blanked or plated over to show two dots and new trains introduced for service outside the Southern Region after this time usually had no train reporting number display equipment. Many trains intended to run over Southern Region lines were designed to display the numeric route-code portion of the train reporting number, which they still display, usually as a dot-matrix display.
Components.
The main purpose of the headcode is to assist the signaller in routing and regulating the train correctly, and it is especially useful if services are disrupted. After the introduction of the four-character codes, originally it was intended for signallers to visually note the train by the number displayed on its front; with the coming of automated systems the number has been retained internally within timetables and signalling systems but with some exceptions detailed above is no longer displayed on trains.
Train classes.
For operational reasons, certain trains have priority in running. To help operating staff, they are grouped into classes; these were formerly identified using letters. When the letter groups were replaced by numerals on 18 June 1962, the classifications became:
The classes are periodically revised, and , the classes have been:
Destination letters.
For long distance trains, the country is split up into areas based upon the old British Rail regions. Each one is assigned a letter as follows:
A train going from one region to another is given the letter of the destination region in its headcode. Prior to 1967 N was used to signify trains destined for the erstwhile North Eastern region.
For trains internal to a region, the remaining letters can be used to indicate either:
Some areas within the Midland region are:
While on the Western:
Examples from the Scottish Region include
Other regions can use these letters for different areas, but the inter-regional codes have the same meaning throughout the country.
In 2007, a special letter Q was introduced for track recording trains, such as the Network Rail New Measurement Train. This emphasises to signallers that the train is to run its booked route as it is recording, not to be diverted without the prior knowledge of the controller. Prior to this, trains operated by British Rail Research Division used the letter T.
The letters X and Z are generally reserved for special use – see Special numbering.
Individual identifier.
Because there are many trains of the same type heading for similar destinations (for example, most expresses to Scotland have headcodes beginning with 1S) the last two digits are used to separate individual services or to indicate the route (generally for suburban services).
Special numbering.
It is common practice for empty coaching stock (class 5) trains on the way to form a service or returning to depot having completed a service to run with the same code as that service, with the 5 prefix. For example, the 23:03 East Midlands Trains 5D69 service from Leeds to Neville Hill TMD is formed using the coaching stock from the terminating 1D69 service from London St Pancras. Similarly, locomotives on the way to pick up or having dropped off a train, or running round to change the direction of travel, are given the train number but with a 0 prefix. For example the 00:40 Caledonian Sleeper 0B16 light locomotive movement from Edinburgh Waverley to Craigentinny TMD arrives on 1B16 from Aberdeen.
An unusual situation arose with the opening of the Channel Tunnel: many continental train reporting numbers are all numeric. Eurostar trains therefore have a 9Oxx or 9Ixx reporting number in Britain and a corresponding 90xx or 91xx number in Europe, neatly utilising the similarity between the letters O and I and the numbers 0 and 1 to unite the two reporting number systems.
Some passenger services operate with class 9s to differentiate them from other services. As at October 2018, the following services operated with class 9 reporting numbers:
Trains with some specific requirements, such as out-of-gauge loads or the Royal Train, run with the letter X, and special trains not in the regular train service (e.g. charters, railtours, emergency trains or as-required locomotive moves) have Z. Automatic Route Setting code prevents the automatic routing of trains with the letter X in their headcode and signallers must route these trains manually. The former "White Rose" service from London King's Cross to Leeds ran with a prefix of 1X due to the train's unusually long length.
Rail replacement bus services are run under the headcode 0B00. In a similar manner, shipping services run on behalf of or in tandem with rail services are given headcode 0S00. An example of 0S00 is the Portsmouth Harbour to Ryde Pier Head ferry service.
Tyne & Wear Metro trains have 3-digit numbers which are displayed in the driver's cab window. Those on the Sunderland line are generally in the range 101 – 112, and the set operates all day on the Newcastle Airport to South Hylton route with this number. When on Network Rail metals (i.e. south of Pelaw to South Hylton) the initial digit '1' is replaced by '2I' to give a 4-digit TOPS Train Reporting Number, e.g. train 104 becomes 2I04, although the 3-digit number in the cab remains unaltered.