The car you board decides your exit — reading a Tokyo platform's floor marks

On a Tokyo platform, the most useful information is under your feet. Painted lines and small tiled numbers mark where each door will open, and if you read them before the train arrives, you can decide something the map never told you: which car puts you closest to the stairs at the far end.

The marks on the ground

Look down where people already stand and you will see pairs of lines angled into a lane — the seiretsu jōsha (整列乗車), the orderly-boarding queues. Usually there are two sets in two colours: one for the next train, one for the one after. On lines that run more than one kind of service — a Chūō rapid (快速 kaisoku) behind a local (各駅停車 kakueki-teisha), an Odakyū express behind a slow train — the marks split by shape as well as colour, a circle for one service and a triangle for another, because the trains are a different length and the doors land in a different place. Stand behind the line that matches the service shown on the board above you.

A step in front of the queue runs a yellow strip of studded tiles, the tenji burokku (点字ブロック), tactile paving for the blind and the edge nobody crosses until the doors open. The platform announcement calls it the kiiroi sen (黄色い線), the yellow line, and asks you to wait behind it. Arrivals step off through the gap in the middle of your lane; you file in after they clear. Nobody announces the queue. The floor does.

Choosing a car for the far end

Every door has a jōsha ichi (乗車位置), a boarding position, numbered by car and door — a small "3-2" underfoot reads as car three, door two. At a large interchange the gap between car three and car eight is a real walk: at Shinjuku or Ōtemachi, boarding the wrong end can cost five minutes and a wrong staircase once you arrive. Regular riders solve this once. They learn that at their destination the west stairs sit level with the second door of the front car, and they board there every morning.

You can borrow the habit without living it. The pillars along the platform carry a gōsha annai (号車案内), a car-position chart showing which car lands nearest each exit and each transfer. The same information sits inside the route apps — Yahoo Norikae Annai, or Japan Transit Planner in English — under a line that reads something like "near the stairs" or "convenient for the exit." Pick the car once, notice where the stairs met you, and the next day you step off into the exit rather than the length of the platform.

The car that isn't yours at rush hour

One position on the floor is not a free choice. During the weekday morning peak, one car — usually near the front or the back of the set, marked in pink on the ground and on the doors — is the josei senyō sha (女性専用車), the women-only car. It is restricted only during the posted hours, generally the thick of the morning rush, and outside them anyone may ride it. The sign states the times and the days in English as well as Japanese, so read it rather than guess: the window differs by line, and a car that is women-only on the Chiyoda line around 08:00 is open to everyone by mid-morning.

足元の線を見れば、次の電車で並ぶ場所がわかる。

What it costs, and the one mistake

None of this costs anything to read, and the ride itself starts from a base fare of around ¥150 on JR lines when you tap a Suica or Pasmo — the IC cards sold from any ticket machine for a ¥500 refundable deposit plus whatever you load onto them. Tap in at the orange reader on the way through the gate, tap out at your exit, and the fare for the distance is deducted; there is no zone to guess at. Trains on the Yamanote and the Marunouchi come every few minutes, so a missed one is not a lost morning.

The mistake to avoid is the kake-komi jōsha (駆け込み乗車), the last-second dash through a closing door. The chime sounds, the doors give no forgiving second bounce like an elevator, and if you jam one, staff will hold the whole train while they check it. The next service is already marked on the board — and if you looked down first, it already has your car waiting on the floor. Read the ground before you read the arrivals board. It was written there, in paint and tile, for anyone willing to look down before looking up.