How it works

Kotodur combines the Bangladesh Railway timetable with GPS from passengers' phones to show where a train is, how late it is, and when it should reach each station. No app to install, no account, no ads.

Where positions come from

1. Live GPS: when someone on the train taps "I'm on this train", their browser sends its position every few seconds. With several passengers the median position is used, so one bad GPS reading cannot throw the result off.
2. Estimated from last GPS: when sharing stops, the train is projected forward from its last known position and delay at timetable speed (for up to 90 minutes).
3. Timetable: with no GPS at all, the timetable position is shown and clearly labelled as an estimate.

Every position says which source it comes from, how many passengers are sharing and when it was last updated.

How wrong or fake positions are kept out

• The position must be close to that train's line.
• It must fit the timetable — far too early or implausibly late is rejected.
• Successive positions from one phone must move forward at train speed; going backwards or faster than 150 km/h is rejected.
• A new phone only counts once the train has moved at least 1 km, or when it agrees with other passengers. Standing on a platform cannot place a train.
• Positions more than 3 km from the other passengers are dropped.

How expected times are worked out

From the current position, the timetable running time to each following station is added. Trains do not leave a station before the scheduled time, so delays shrink a little at long halts — the estimate does the same.

Privacy

• No name, phone number or account is ever asked for.
• While sharing, your browser makes a random id; the server only keeps a hash of it.
• Your latitude and longitude are not stored — only how far along the line the train is. That is deleted after 2 days; the train's combined position history (not linked to any phone) is kept for 30 days.
• No ads, trackers or third-party analytics. Only map tiles come from OpenStreetMap.
• Tapping "Stop" or closing the page ends sharing immediately.

Limitations

• Live positions depend on passengers. If nobody shares, only the timetable can be shown.
• Browsers pause GPS in the background, so the page has to stay open while sharing (it tries to keep the screen on).
• Rail lines on the map join stations, so in places they are off the real track.
• Bangladesh Railway can change timetables. Confirm at the station or with official sources before you travel.

Sources

Timetables, stations and fares: Bangladesh Railway Open Data (MIT licence, version 3.0.0, updated 2026-10-04) — 224 trains, 415 stations. Map: © OpenStreetMap contributors. Kotodur is not affiliated with Bangladesh Railway.