How can we help?

Choo! doesn't come with spots: you choose your own, anywhere you can stand beside a railway. Long-press the map where you'll stand (or tap +, tap the map, then Next).

1. Long-press the map where you'll stand. Choo! suggests a name from the street.
2. It finds the nearest railway, and picks National Rail or Tube & TfL and the line for you.
3. National Rail: choose the nearest station, and the very next station along the line past your spot, so no junction comes between them. Tube & TfL: choose the station, the line, and the station on the other side of your spot.
4. Tap Check for Trains to see what's due each way before you add it. "No trains due" usually means a different station is needed.

To change a spot later, open the list (top left), where you can also reorder and delete spots.

Yes. When a train passes, tap A train just passed on the spot's details. Choo! learns from your last few taps in each direction and fine-tunes that spot's timings. You can also edit a spot's timings by hand, in 5-second steps.

Times are estimates, worked out from the timetable and where each train has been seen. In the last couple of minutes before a National Rail train reaches your spot, its time comes straight from the railway's signalling, so the countdown can jump a little as it gets more precise. Trains can be held at signals or stations, so it's worth keeping an eye out for a minute either way.

National Rail trains across Great Britain, including trains that don't stop, freight and empty trains; and in London, the Tube, DLR, Overground and Elizabeth line. Trains in Northern Ireland, heritage railways, and trams aren't included.

Allow notifications when Choo! asks. You'll get one 5 minutes before an unusual train (freight, test, charter, leaf-clearing and so on) passes a spot, for the next couple of hours after you last had Choo! open. Each kind can be turned on or off in Choo!'s Settings.

Open a spot and choose Follow on the Lock Screen. The countdown then shows on your Lock Screen and in the Dynamic Island while you walk there. There are Home Screen and Lock Screen widgets too: add them as you would any other widget.

Choo! draws trains along the real shape of the track where it has it, which so far is south-west London. Elsewhere, a train moves in a straight line between the places it's timed, so on a curvy line it can look like it's taking a shortcut. The countdown isn't affected.

Use Report an Issue: it's in Settings, on a spot or a train, or shake your phone. Write a note about what went wrong and tap Send. It sends the last two hours of what the app received and showed, a screenshot if you choose, and your spots, with no account or contact details. The privacy policy has the details.

Choo! is free to download, with no ads, no accounts and no tracking. It's on TestFlight now, Apple's way of trying apps before they're on the App Store.

Choo! is made for a grown-up to hold while you watch together. Please watch from public places behind a fence or barrier, never on or near the tracks, and hold little hands near the railway.

No. Choo! is independent, and isn't affiliated with or endorsed by Transport for London, Network Rail, National Rail or any train company. It uses their open data, credited at the bottom of the home page and in the app's Settings.