Are these real departures?

Yes — live prediction data from the MBTA's own public v3 API, refreshed every 45 seconds.

How is this different from the Rail Board?

The Rail Board shows Swiss mainline trains. This shows a mixed North American urban network — subway, bus and commuter rail leaving the same station.

Why did a duplicate train disappear?

The MBTA lists one physical train under every route pattern that shares its track. The board shows each train once.

No. The MBTA v3 API is key-less for this kind of request.

Yes — free, no download, in your browser.

Why does the arrival time change between refreshes?

Predictions are updated as service conditions change, so the estimate can shift with delays or catch-up. Treat any single figure as an estimate rather than a promise.

What is the difference between scheduled and predicted time?

The schedule is the planned stop time, while a prediction is the MBTA’s estimate of the actual arrival or departure time. They can differ when a vehicle is running early or late.

What do the colours of the lines mean?

They are names for routes: Red, Orange, Blue and Green identify the subway and light-rail lines. The MBTA assigned the colours in 1965, and they help riders tell the lines apart on maps and signs.

Transit Departures Screensaver

The Transit Departures screensaver shows real upcoming MBTA departures from a Boston-area station on a split-flap board. It's free, runs in your browser, and ESC exits.

How the Transit Departures screensaver works

Pick a station and the saver reads live departure predictions from the MBTA's own key-less public API.

Each row shows the departure time, the line, the destination and how many minutes away it is.

Cancelled trips are dropped, and trains listed under several route patterns are shown only once.

It refreshes every 45 seconds, and the tiles riffle as departures update.

The MBTA and its real-time prediction feed

The Massachusetts Bay Transportation Authority, usually called the MBTA or simply the T, runs rapid transit, light rail, buses, commuter rail and Boston Harbor ferries. Its Green Line includes the Tremont Street Subway, which opened in 1897 and is described as the first subway in the United States. The rapid-transit lines are known by colour: Red, Orange and Blue, plus the light-rail Green Line, the Mattapan Line (an extension of the Red Line) and the Silver Line bus rapid transit service.

The MBTA publishes a V3 developer API with three related kinds of data: schedules, which are the planned stop times; predictions, which are predicted arrival and departure times; and vehicle positions. Each prediction is tied to a stop, which corresponds to the platform where the vehicle will be. Predictions can be requested alongside schedules, so a listing may show a time that differs from the posted timetable when a vehicle is running late or early.

Predictions are estimates and can change from one refresh to the next, and entries can appear or disappear as service changes. The API describes the data; it does not replace the MBTA’s own service alerts, which remain the authoritative source for disruptions.

A worked example

At South Station the board shows a Red Line train to Park Street in 1 minute, a Providence commuter train departing now, and the next several Red Line trains behind them — the tiles clattering as each one moves up.

Settings & tips

Station switches between ten Boston-area stations.
Board width/height resize the tile grid.
Flap click sound adds the mechanical clatter (off by default).

Frequently asked questions

Are these real departures?: Yes — live prediction data from the MBTA's own public v3 API, refreshed every 45 seconds.
How is this different from the Rail Board?: The Rail Board shows Swiss mainline trains. This shows a mixed North American urban network — subway, bus and commuter rail leaving the same station.
Why did a duplicate train disappear?: The MBTA lists one physical train under every route pattern that shares its track. The board shows each train once.
Is a key needed?: No. The MBTA v3 API is key-less for this kind of request.
Is it free?: Yes — free, no download, in your browser.
Why does the arrival time change between refreshes?: Predictions are updated as service conditions change, so the estimate can shift with delays or catch-up. Treat any single figure as an estimate rather than a promise.
What is the difference between scheduled and predicted time?: The schedule is the planned stop time, while a prediction is the MBTA’s estimate of the actual arrival or departure time. They can differ when a vehicle is running early or late.
What do the colours of the lines mean?: They are names for routes: Red, Orange, Blue and Green identify the subway and light-rail lines. The MBTA assigned the colours in 1965, and they help riders tell the lines apart on maps and signs.

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