With how crowded Japan's cities are, it's no surprise that in Tokyo
the trains are vital to getting around. Tokyo's rail network is the most extensive of any metropolitan area in the world: on a given day, about 20 million passengers use the network's more than 1,000 stations in Tokyo, Saitama, Chiba, and Kanagawa Prefectures
to get from here to there. Shinjuku Station is registered by Guinness as the busiest train station in the entire world at 3.64 million passengers a day. With all that, the actual subways of Tokyo don't make up that big of a percentage of the use - of those 1000+ stations only 290 of them are actually subway stations. Still, an estimated 8.7 million people use them each day, the highest of any city in the world.
But wait - why is it then that a list of the world's busiest metro systems doesn't have Tokyo first (currently Beijing) nor second (Seoul) nor third (Shanghai) nor fourth
)? Well, there are actually two different subway systems in Tokyo, run by two different administrations. While the two systems cooperate with one another in several areas (most notably the unified system of labeling lines and stations), the separate administrations also mean any trip using both systems incurs a surcharge via a special transfer ticket - a similar situation exists if you wanted to transfer to a line run by JR East, including the Yamanote Line (a new card system called PASMO was introduced in 2007 that simplified the process).
Each line is marked by both a unique color and a symbol containing a circle with that color, with a Latin alphabet letter corresponding to the first letter of that line's Romanized name (generally - in cases of overlap or other potential confusion another letter is used) - the two systems' lines don't repeat either between each other. Each station, in turn, is given a designation of that line's letter followed by what number stop it is along the line for ease of use by foreigners. For example, G-01 is the first station on the Ginza Line (Shibuya), G-02 is the second station on the line (Omotesandō), G-03 is the third (Gaiemmae), and so on. Multiple designations can apply to the same station - Omotesandō is also the fourth station on the Chiyoda Line (C-04) and the second on the Hanzōmon Line (Z-02).
The more extensive and used of the two systems. This was formerly the Teito Rapid Transit Authority (or Eidan), run by the Ministry of Land, Infrastructure, and Transport before being privatized in 2004 (albeit co-owned by the Japanese government and the Tokyo Metropolitan government). The company also runs several commercial developments near several of their stations.
- Chiyoda Line (green, Line 9)
- HanZōmon Line (purple, Line 11)
- Fukutoshin Line (brown, Line 13)
- The newest line, opened in 2008
- Hibiya Line (silver, Line 2)
- Ginza Line (orange, Line 3)
- Oldest subway line in Asia, opened in 1927
- Marunouchi Line (red, Line 4)
- Also contains a branch line, designated with a lower case "m".
- Namboku Line (emerald/dark aqua/teal, Line 7)
- Tōzai Line (sky blue, Line 5)
- According to Tokyo Metro this is the most crowded line in the system, running at 199% capacity during rush hour.
- Yūrakuchō Line (yellow, Line 8)
The smaller of the two systems, run directly by the Tokyo Metropolitan government. Toei also runs several light rail lines, bus lines, and even a fiber optic network and several power generators.
- Asakusa Line (rose, Line 1)
- MIta Line (blue, Line 6)
- ŌEdo Line (magenta or ruby, Line 12)
- If the complexity and headache of having two separate subway systems requiring separate fares in the same city annoys you, blame this - Toei incurred a ton of debt constructing this entirely-underground line in The Nineties (the second-longest rail tunnel in Japan after the Seikan Tunnel connecting Honshu and Hokkaido across the Tsugaru Strait) and Tokyo Metro is reluctant to assume this debt in any deals for the two systems to come under one administration.
- Shinjuku Line (leaf green, Line 10)
Other Major Lines (not part of either system, but still frequently used)
- Yamanote Line - operated by JR East. Runs in a loop that circles around the 23 special wards, frequently marked on both Tokyo Metro and Toei Subway station maps.
- Rinkai Line - underground line run by a non-profit organization near Tokyo's waterfront, connects from Osaki to the waterfront islands of Odaiba.
- Yurikamome Line - Another public transit line that runs to Odaiba. Unlike the Rinkai Line, it is a tram rather than a rail system, runs above-ground, and is driverless. Tickets are more expensive, but the ride offers scenic views of the city including a 270-degree loop before it crosses Rainbow Bridge.
- Saitama Rapid Railway - a suburban commuter line that is underground nearly the entire length.