What is Darwin? National Rail's live train data explained

What is Darwin National Rail data, in plain terms? Darwin is National Rail's live train information system. It takes the timetable, adds live reports of where every train actually is and updates from the train companies, and works out expected departure and arrival times, platforms and cancellations for trains across Great Britain. It's the system behind National Rail Enquiries, and it feeds many station screens and train times apps. When your phone, the screen at the station and a home board all agree that the 18:32 is now expected at 18:40, that's usually Darwin they're all reading.

What does Darwin actually do?

Think of it as the railway's running commentary. The timetable says what should happen. Darwin says what is happening, and what's likely to happen next.

For each train at each station, it holds things like:

• the booked time and the expected time
• the platform, once it's been confirmed
• whether the train is cancelled, and the reason given
• the stations it will call at after this one
• which train company runs it and, often, how many coaches it has
• messages for the station, such as engineering works or disruption

It doesn't drive the trains or set the signals. It's an information system, working out the most likely picture from what it's told.

Where does Darwin get its information?

Two broad sources. One is reports of train movements as trains pass points along the line, which come from the railway's signalling and train-reporting systems. The other is the train companies themselves, whose control rooms update things like cancellations, platform changes and the reasons for delays.

Darwin puts those together with the timetable and predicts forward. It can only be as current as its last report, though, so a train sitting between two reporting points can look on time for a minute or two before the next report catches up with it. If a train from Bristol Temple Meads is running six minutes late as it passes Swindon, Darwin works out what that probably means for Reading and London Paddington further along.

Why do expected times keep changing?

Because they're predictions, recalculated as the train goes. A few common reasons for a number to move:

So a time that jumps about isn't the board being broken. It's the railway's best guess getting better as the train gets closer. Our guide to departure board status words goes through what each one means, and why trains are delayed or cancelled covers the causes.

Why is there sometimes no platform?

Platforms are often only confirmed shortly before a train arrives, especially at big stations where trains get shuffled between platforms to keep things moving. At busy London termini such as Euston, you'll often see a crowd waiting under the screens for exactly this reason. Some smaller stations don't publish platform numbers at all. When there's nothing to show, a good board shows nothing, and fills it in as soon as the station gives it out.

Where can you see Darwin data?

In lots of places, many of which you'll already use:

• the National Rail Enquiries website and app
• many station departure screens
• train company and ticket apps
• home departure boards, browser boards and the odd hobby project

That shared source is why times broadly match wherever you look. Small differences usually come down to how often each screen or app refreshes.

How does TrainTicker use Darwin?

TrainTicker reads Darwin through the Rail Data Marketplace, where National Rail makes its live departure data available. It uses the live departure board for your station, plus the details of the next train so it can show where that train is (for example, "Left Swindon", the last place it called). It checks for changes every 10 seconds.

On the board itself, you see what a station screen would show you: the time, the destination, the platform when it's known, and the status, whether that's on time, expected later, delayed or cancelled, with the reason scrolling underneath. Calling points, the operator and number of coaches, and station notices scroll along too. There's a full walkthrough of the layout in how to read a train departure board.

Because the data comes from National Rail, it covers every National Rail station in Great Britain, from Penzance to Thurso. You choose yours by name or its three-letter code. And the train times are free for life, with no subscription. You can see the same live data in the free browser demo right now, or order a board for £199.99.