Early departure times

[David Mountain]

We've just noticed early arrival and departure times (earlier than the scheduled times) being returned from the Darwin Web Services (Staff) feed.

We not sure we've seen these before - I think previously if services arrived early, the estimated time of departure was set to the scheduled departure time.

Just checking if this is a recent change, or for ServiceItem objects, etd values have always been able to be earlier than the std value?

many thanks

Dave

[Rail Ale Fan]

Hi Dave,

Do you have, or could you capture when you next observe this, an example RID and location?

[David Mountain]

I've capture one example. It was for Leeds as 12:11 on 5th Feb.

This example looks to be an example of a departed service staying on the board, and the actual departure being a few seconds earlier than the scheduled departure. So its the atd that is earlier than the std.

I haven't been able to capture an example where the etd is earlier than the std.

So it could be seen as erroneous for a service that has departed to still be on the board? But I expect there is a tolerance of a few seconds as it pulls out of the station?

{

  "rid": "201902056711141",

  "uid": "C11141",

  "trainid": "1V56",

  "rsid": "XC165000",

  "sdd": "2019-02-05",

  "operator": "CrossCountry",

  "operator_code": "XC",

  "sta": "2019-02-05T12:07:00+00:00",

  "ata": "2019-02-05T12:06:04+00:00",

  "arrival_type": "Actual",

  "std": "2019-02-05T12:11:00+00:00",

  "atd": "2019-02-05T12:10:54+00:00",

  "departure_type": "Actual",

  "departure_source": null,

  "platform": "11C",

  "origin": {

    "location": {

      "location_name": "Glasgow Central",

      "crs": "GLC",

      "tiploc": "GLGC"

    }

  },

  "destination": {

    "location": {

      "location_name": "Plymouth",

      "crs": "PLY",

      "tiploc": "PLYMTH"

    }

  },

  "category": "XX",

  "activities": "T           "

[Rail Delivery Group]

Hi,

To answer your main question, nothing has changed in this area recently and estimated times should not be earlier than scheduled times - please provide examples if you do spot any and we'll investigate.

Darwin's actual times are based on TD berth steps with an offset, so as the service steps out of the berth the offset is taken away from the recorded berth step to determine the time the train departed. As trains obviously don't pull away at exactly the same speed, and depending on exactly where the berth sits in relation to a platform the offset can be quite large, then as you guessed there is a certain margin of error. If this is happening consistenty for departures at a particular location then feel free to let us know and we'll investigate whether the berth offsets we have need updating.

RDG