Is the TD feed national?

[Andrew Larcombe]

Hi all,

I hope someone can help me understand a problem I think I'm having with the TD feeds, specifically train movements.

For the most part I receive messages just fine, but I do have problems with certain areas of the rail network. The Cotswolds
seems to be a good example where I _never_ seem to receive data from trains that I believe are there. I have a specific example from today.

Looking in the Darwin events I can see train P22853 today from Malvern Link (about 1600) to Reading (due about 1805).

Darwin tells me that the headcode of this train is 1P32, but the first TD messages I get for that train are at 1724 in TD area D5.

This seems to be fairly routine - is this because some TD areas or trains or journeys just don't report on movements through some areas?

Thanks,

Andrew
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Andrew Larcombe
and...@andrewl.net

[Gaelan Steele]

Hi Andrew,

I believe much of that area uses absolute block signaling, a rather old method of operation involving people in signal boxes observing trains as they pass and pulling levers. Such areas do not provide TD data, nor do areas using other legacy signaling approaches like tokens. 

I’m not sure off hand if all track-circuit/axle-counter areas provide TD feeds; I’m sure somebody will know better than I do.

Best wishes,

Gaelan Steele

On Feb 16, 2026, at 17:42, Andrew Larcombe <and...@andrewl.net> wrote:



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[Andrew Larcombe]

Hi Gaelan,

Many thanks. Having spot-checked a few additional areas, this looks like the explanation I was looking for.

Thanks again for your quick response,

Andrew

To view this discussion, visit https://groups.google.com/d/msgid/openraildata-talk/2E3F5615-CCF6-4E34-9C0F-BE9EA81AB9C6%40canishe.com.

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Andrew Larcombe
and...@andrewl.net

[Thomas Wood]

Not all TCB (rulebook term, rather than train detection methodology) controlled areas report TD stepping to TRUST, only those areas with modern enough TD and telecommunications technology. Some AB areas did provide TD stepping. It's not a hard and fast rule, but a generalisation.

On Mon, 16 Feb 2026 at 18:36, Gaelan Steele <g...@canishe.com> wrote:

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