201, G01, NS1: how Seoul, Tokyo and Singapore number their stations, and why the others don't

Three of the six cities in the game give every station a number. The other three do not number stations at all. The systems look alike from a distance, but each one handles new lines and extensions in its own way, and the cracks show where a network has grown faster than its numbers.

Seoul: the line is the first digit

Seoul's subway lines number their stations with three digits, and the first digit is the line. City Hall on Line 2 is 201, Anguk on Line 3 is 328. Lines run by other operators use a letter instead: K for the Korail lines such as the Gyeongui-Jungang Line (Munsan is K335) and the Suin-Bundang Line, D for the Sinbundang Line, S for the Ui-Sinseol Line, A for the airport railroad and G for the Gimpo Goldline. Of the 486 Seoul stations in the game, 352 have plain three-digit numbers, 87 start with K, 17 with S, 12 with D, 9 with G and 8 with A.

The interesting cases are extensions added after the numbers were handed out. When Line 1 was extended past Soyosan (100) to Yeoncheon in 2023, there was no number below 100 left, so the three new stations became 100-1, 100-2 and 100-3. Line 2's two short branches do the same at their ends: Sinseol-dong is 211-4 and Kkachisan 234-4.

Because a station shared by two lines keeps one number in the game, the codes you see there are the line that owned it first. Sinsa, for example, appears as 337 from Line 3, even when you ride the Sinbundang Line through it.

Tokyo: a letter and two digits

Tokyo Metro and the Toei subway added station numbers in 2004, with foreign visitors in mind. Each line has a letter and each station a two-digit number in a box of the line's colour: G01 is Shibuya on the Ginza Line, M17 is Tokyo Station on the Marunouchi Line. A station on two lines carries two codes. Azabu-juban, for example, is N04 on the Namboku Line and E22 on the Oedo Line. JR East announced in 2016 that it would number its Tokyo stations too, which is where the Yamanote Line's JY codes come from: Shinagawa is JY25.

The Oedo Line shows the system bending around a loop. It runs from Hikarigaoka to Tochomae, E28, and then round a loop through central Tokyo back to Tochomae. The Oedo Line guide follows the route.

Singapore: two letters, and a few missing numbers

Singapore's MRT used a different scheme until 2001. Stations were coded by region, E for east, W for west, N for north, C for the city and M for Marina, with B for the old branch line. On 31 July 2001 the codes were changed to start with the line, and that is the system in use today: NS for the North South Line, EW for the East West Line, NE, CC, DT and TE for the newer lines.

Some numbers are missing. The North South Line runs from NS1 Jurong East to NS28 Marina South Pier, but there is no NS6 among its stations. The Circle Line has no CC18 either. In the game all 145 Singapore stations have a code, and the interchanges keep the one they had first.

New York, London and Paris: names only

The three oldest systems in the game do not number their stations for passengers. New York numbers and letters its services instead: the 1, the A, the Q. Many of its stations are named after numbered streets, so the names already carry a number, and the same street can have several stations on different lines, which we explain in same name, different station. London and Paris rely on names alone.