Station numbering

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 was 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, which contains the initial part of the line name or number (as seen below) and the station symbol part, which consists of the numerical positioning of the station relative to the railway line and its starting station number (example listed below)

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’ M and the Toei Mita Line uses ‘I’ 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) without regard 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.