Station numbering is a sign system which assigns station codes consisting of a few letters and numbers to train stations. It aims to facilitate navigation for foreign travelers not familiar with the local language by using globally understood characters (Latin letters and Arabic numbers). The system is now in use by various railway companies around the world such as in Mainland China, Indonesia, Japan, South Korea, Singapore, Taiwan, Thailand, and the United States.
Station numbering first introduced—but to less fanfare—in South Korea, by the Seoul Metropolitan Subway in 1983 as a section of Seoul Subway Line 2 (Euljiro 1-ga to Seongsu) was opened.
Its first usage in Japan was in the Nagasaki Electric Tramway where it was introduced in May 1984. The Tokyo subway system introduced station numbering in 2004. Sports events are usually the turning point for the introduction of station numbering in Japan; the Yokohama Municipal Subway introduced station numbering in preparation for the 2002 FIFA World Cup and there was a mass adoption of station numbering in the months leading to the 2020 Summer Olympics.
The station number often consists of two parts: the "Line symbol part", and the "Station symbol part".
The line symbol part is the part that represents the railway line the station is belonged to. Therefore, all stations on the same railway line shares the same line symbol part.
In some countries, such as South Korea and Mainland China, where the railway lines are often named with numbers (e.g. Line 1, Line 15), the number used to name the railway line is used as the line symbol.
In other countries, such as Japan, where the railway lines are often not named with numbers, the line symbol part usually consist of one or two letters, which are often abbreviations of the Romaji notation of the line name, many of them being the initials. However, when there are more than two lines with the same initials in the same region, either of them is often changed in order to avoid duplicated line symbols, even across different company lines (for example, the Tokyo Metro Marunouchi Line uses ‘M’and the Toei Mita Line uses ‘I’ , although the name of the two lines both starts with the letter M). Another method to avoid duplicated line symbols is to assign them in an alphabetical order (A to Z) regardless to the abbreviations.
While most of the station numbering systems follow the aforementioned two styles, there is a few exceptions. Shinbundang Line of Korea uses the line symbol of letter D, even though there is no notable reason preventing them from following the two popular styles presented above. Neo Trans, the line's operating company, mentions it is a part of their branding strategy: to emphasise the latest digital technologies applied to their railway line. Another group of examples of such exceptions is found among minor branch lines operated by Seibu Railway of Japan. One of their railway lines is the Seibu Ikebukuro Line, which has the line symbol of SI (the alphabet abbreviation of the line name). The Seibu Sayama Line, a branch line that splits off from Seibu Ikebukuro Line, shares the same line symbol of SI, even though its own alphabet abbreviation is not SI.
The station symbol part is the part that identifies each station on the scale of one entire railway line. Therefore, there must not be any duplicated station symbols on the same railway line: no more than one station on the same railway line should have the identical station symbol.
In most of the cases, the station symbol is a two digit number. Usually, the starting station of a railway line is assigned number 00 or 01, and stations along the line are distributed sequentially ascending whole numbers (i.e. If the starting station is assigned the number 01, the first station a person traveling outwards from the starting station would encounter will be assigned the number 02, then the station after this will be assigned 03, and so on). It is notable that, unlike other regions of the world, most of the station numbering systems in Korea assigns number 10, instead of number 00 or 01, to the starting station of a railway line. This is known to be a part of preparation for the possibility of line extension, so that the stations on the extended section could be easily numbered, rather than shifting and renumbering the entire line (e.g. the extension of Seoul Subway Line 4 from Sanggye station (410) to Danggogae station (409)).
As for any branch sections branching off from the main line (like a ‘Y’ shape track), there are several possible methods to number the stations located on the branch sections.
Likewise, there are several possible methods to number the new stations constructed after the initial opening of the railway line. Written inside each bracket below are the station numbers which would be assigned to the new stations under each method, assuming an imaginary case where, for example, two new stations are added between stations of number 07 and 08.
Sub-Heading 1 are sorted in alphabetical order.
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