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| Last Sent 18/05/2016 at 09:49 #82495 | |
Andrew G
552 posts |
Are there any standards/conventions for 'Last Sent' train description berths? I used to think these related to the last train which had passed between control areas until I spotted a description stepping into a 'Last sent' berth when the train was still under the control of Walsall PSB. It was then explained to me that the berth displayed the last Train Description which had been transmitted to the adjacent box. Background to the query is I have noticed on York N&S that the 'Last sent' berth is only populated when a train passes York's last signal. In some cases (e.g. Gascoigne Wood & Poppleton) this will be too late for the receiving Signaller to start to deal with the incoming train before it starts to receive adverse aspects. Which is correct or is it one of these nuances with signalling which will depend on the age of the installation and/or signalling contractor? Log in to reply |
| Last Sent 18/05/2016 at 15:51 #82504 | |
GeoffM
6377 posts |
You're going to love this: It depends! I've seen some that copy in to the last sent as the description gets sent to the next box on the last signal; others that transmit on passing the point of no return (eg plain line, TD copies when going over the junction). While we use real TD data where available, sometimes the last sent berths are altered slightly as each sim "owns" each berth and a last minute step might not be possible once the next box has "got" the description. Another example, taking York, Strensall doesn't have a train describer except to inform York what's coming next, so that gets input manually sometime in a 10 minute window roughly, but on the sim we do have an off-screen TD area that copies to the approach berth at a defined point. SimSig Boss Log in to reply |
| Last Sent 18/05/2016 at 16:09 #82507 | |
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Andrew G
552 posts |
Thanks for the context.
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| Last Sent 18/05/2016 at 16:10 #82508 | |
madaboutrains
316 posts |
In some of the 233 boxes that I have been to seem to lose the Last sent berth after some time or are not working? how are these cleared normally?
RIP Feltham Panel 1 Log in to reply |
| Last Sent 18/05/2016 at 16:39 #82509 | |
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GeoffM
6377 posts |
" said:In some of the 233 boxes that I have been to seem to lose the Last sent berth after some time or are not working? how are these cleared normally?Some older installations have a 5 minute (or some other figure) timer to clear out the last sent berths. Most train describers I've SimSig Boss Last edited: 18/05/2016 at 16:40 by GeoffM Log in to reply |
| Last Sent 19/05/2016 at 07:53 #82527 | |
kbarber
1743 posts |
Where boxes are close together a description may be transmitted early, provided there is a route set towards the line on which it will transmit. Believe it or not, this feature was available as early as 1949, on the Liverpool St - Shenfield line; admittedly it didn't use the modern 4-character headcode descriptions and the describer display was in the form of screens above the panel, but in all other respects it was a modern train describer. In the inner area (Bethnal Green, Bow Junction, Stratford, Forest Gate and the two Ilford boxes - possibly Goodmayes as well) it would be usual for the description to be pretransmitted some time before the train even passed the box; when it was, the description would appear in the 'last sent' berth (the very top line of the screen) as well as remaining in position further down the screen (but a white visual would illuminate beside it to indicate it had pretransmitted). I never had the opportunity to see it work under serious pressure, but there were several locations where the signalling would have allowed more then one train to be in the area beyond the 'pretransmit' point and I suspect, in that case, pretransmit would still operate and the 'last sent' might well refer to a train two or three lines down. In that case I certainly never saw anyone clear out a 'last sent' and I'm not sure it was even possible. Certainly it never, so far as I am aware, self-cleared. Last edited: 19/05/2016 at 07:54 by kbarber Log in to reply |