Why the arrival predictions are incorrect when there are delays

[tfl_enthusiast]

Hi

I’m new to using tel unified api and I’ve noticed that the arrival prediction isn’t correct when there are delays or cancellations

I’m relaying on time_to_station value to decide whether the train is at the station or not. All I want to know if Elizabeth line has arrived at a specific station or not and if a train has arrived, then I need to find out if that train has left or not.

I’m putting a condition that if time_to_station < 50 then assume that the train has arrived at the station.

If you look at the screenshot you can see that time_to_station value is not reliable and also according to national rail that train shouldn’t be anywhere close to the station.

I’m using
https://api.tfl.gov.uk/Line/{line_id}/Arrivals/{stop_point_id}?direction={direction}

Where line_id the the line I’m interested in
stop_point_id is the station I’m interested in
and direction is inbound

Any help or advice on this will be greatly appreciated.

Thanks

[jamesevans]

hi @tfl_enthusiast

For Elizabeth line and Overground, we have an ArrivalDepartures operation under StopPoint that may serve your purpose better.

https://api.tfl.gov.uk/stoppoint/910GWCHAPEL/ArrivalDepartures?lineIds=elizabeth

Each prediction has enhanced data.

  {
    "$type": "Tfl.Api.Presentation.Entities.ArrivalDeparture, Tfl.Api.Presentation.Entities",
    "platformName": "Platform B",
    "destinationNaptanId": "910GHTRWTM4",
    "destinationName": "Heathrow Terminal 4 Rail Station",
    "naptanId": "910GWCHAPEL",
    "stationName": "Whitechapel Rail Station",
    "estimatedTimeOfArrival": "2024-08-08T12:24:00Z",
    "scheduledTimeOfArrival": "2024-08-08T12:24:00Z",
    "estimatedTimeOfDeparture": "2024-08-08T12:24:00Z",
    "scheduledTimeOfDeparture": "2024-08-08T12:24:00Z",
    "minutesAndSecondsToArrival": "91:0",
    "minutesAndSecondsToDeparture": "91:0",
    "departureStatus": "OnTime"
  },

Hopefully this will provide you what you need.

Many thanks,
James