Tom
Administrator
Signalfel?
Posts: 4,196 
|
Post by Tom on Oct 11, 2021 20:57:54 GMT
No, because the software is designed assuming a specific commissioning order. There's no opportunity to deviate from that.
The current issues are with the commissioned area and the intention is to sort that out before commissioning SMA5.
|
|
|
|
Post by roman80 on Oct 11, 2021 21:15:59 GMT
No, because the software is designed assuming a specific commissioning order. There's no opportunity to deviate from that. The current issues are with the commissioned area and the intention is to sort that out before commissioning SMA5. I am convinced from a passenger’s perspective waiting on the platform each evening the new system brings trains into the westbound platform at Westminster with a greater time gap between trains than the old system, even when they are clearly stacked behind each other as shown on the indicator board. Is that one? |
|
Tom
Administrator
Signalfel?
Posts: 4,196
|
Post by Tom on Oct 11, 2021 21:39:20 GMT
It's not one I'm aware of. One thing that is noticeable about the new system is that if everything is on time, it won't rush around - journeys can appear to be quite slow when actually they're spot on against the timetable. Conversely when the service is running behind, it'll turn up the speed to try and get trains back to time.
|
|
North End
Beneath Newington Causeway
Posts: 1,769
|
Post by North End on Oct 11, 2021 23:11:17 GMT
No, because the software is designed assuming a specific commissioning order. There's no opportunity to deviate from that. The current issues are with the commissioned area and the intention is to sort that out before commissioning SMA5. I am convinced from a passenger’s perspective waiting on the platform each evening the new system brings trains into the westbound platform at Westminster with a greater time gap between trains than the old system, even when they are clearly stacked behind each other as shown on the indicator board. Is that one? It’s certainly the case on the Northern that many locations have a worse platform re-occupation time than what existed before, and even more unfortunately some of these coincide with some pinchpoint locations where this is particularly undesirable. There is work going on to address this, however in terms of timescales this seems to be measured in decades. In reality much of this work is what could be said to be timetable-led - they will do the minimum possible to allow a proposed timetable to be achieved. This is why the Northern has seen a few tweaks plus some easing of speed restrictions, as part of the preparation for the current WTT. If a timetable appears which needs either a more intense headway and/or quicker running times to squeeze more mileage out of the same fleet size, then more mods will happen. But generally Seltrac isn’t anything that shouts wow - on the contrary it’s pretty mediocre in my view. It is, of course, 1980s technology, albeit with refinements. It perhaps doesn’t help that LU have tagged their own requirements onto the system, one being that a train must only be signalled for its final entry into a platform once it can be assured of not having to be brought to a stand part way in (does this apply on the JLE at PED stations?). This requirement in particular is quite destructive. |
|
Chris M
Global Moderator
Forum Quizmaster
Always happy to receive quiz ideas and pictures by email or PM
Posts: 19,766
|
Post by Chris M on Oct 11, 2021 23:25:37 GMT
It perhaps doesn’t help that LU have tagged their own requirements onto the system, one being that a train must only be signalled for its final entry into a platform once it can be assured of not having to be brought to a stand part way in (does this apply on the JLE at PED stations?). This requirement in particular is quite destructive. This restriction applies on the DLR too, and while it doesn't happen that often it's clear that it causes wasted time at places like Shadwell westbound. Most annoyingly perhaps it means that it is not possible to signal a northbound train into platform 2 at Mudchute while a train is leaving the bay platform. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Oct 12, 2021 4:55:47 GMT
It's not one I'm aware of. One thing that is noticeable about the new system is that if everything is on time, it won't rush around - journeys can appear to be quite slow when actually they're spot on against the timetable. Conversely when the service is running behind, it'll turn up the speed to try and get trains back to time. The joys of running a new signalling system with a timetable not fit for purpose in a automatic area. But having travelled on it myself its very good at self regulating itself |
|
Tom
Administrator
Signalfel?
Posts: 4,196
|
Post by Tom on Oct 12, 2021 6:29:12 GMT
It perhaps doesn’t help that LU have tagged their own requirements onto the system, one being that a train must only be signalled for its final entry into a platform once it can be assured of not having to be brought to a stand part way in (does this apply on the JLE at PED stations?). This requirement in particular is quite destructive. This has existed as a requirement (though not always expressed as such!) since the early Victoria line days, though it was possibly less noticeable there. It certainly exists on the Central line. |
|
|
|
Post by jimbo on Oct 12, 2021 6:55:03 GMT
Is my memory perhaps faulty? I recall an original Victoria Line train following another into the platform, perhaps a 4-car length between them?
|
|
|
|
Post by Chris L on Oct 12, 2021 8:38:24 GMT
Is my memory perhaps faulty? I recall an original Victoria Line train following another into the platform, perhaps a 4-car length between them? The Victoria line is much more straightforward than the SSL. |
|
rincew1nd
Administrator
Junior Under-wizzard of quiz
Posts: 10,286
|
Post by rincew1nd on Oct 12, 2021 13:08:04 GMT
Most annoyingly perhaps it means that it is not possible to signal a northbound train into platform 2 at Mudchute while a train is leaving the bay platform. This sounds more like a generous overlap on the 'starter' rather than a platform occupation restriction. |
|
Tom
Administrator
Signalfel?
Posts: 4,196
|
Post by Tom on Oct 12, 2021 20:24:21 GMT
Is my memory perhaps faulty? I recall an original Victoria Line train following another into the platform, perhaps a 4-car length between them? I think so. While it's been a few years I'm fairly sure you couldn't get two trains in the same platform - I'll recheck my old notes. |
|
North End
Beneath Newington Causeway
Posts: 1,769
|
Post by North End on Oct 12, 2021 22:22:47 GMT
Is my memory perhaps faulty? I recall an original Victoria Line train following another into the platform, perhaps a 4-car length between them? I think so. While it's been a few years I'm fairly sure you couldn't get two trains in the same platform - I'll recheck my old notes. It did happen, sort of. If a train was right up the back of another, the home signal would clear from red to white and the second train would follow the first quite closely, relying on nothing out of course happening to slow or stop the first. If something did happen then the second train would sooner or later encounter a track circuit with no code and get tripped, which if the first train was “pulled down” leaving the platform could well result in two trains in a platform length. Needless to say in the final years of the old Vic signalling this exact scenario happened, which resulted in much jumping up and down from the RMT, and of course no one able to explain what had *actually* happened! |
|
North End
Beneath Newington Causeway
Posts: 1,769
|
Post by North End on Oct 12, 2021 22:29:04 GMT
It perhaps doesn’t help that LU have tagged their own requirements onto the system, one being that a train must only be signalled for its final entry into a platform once it can be assured of not having to be brought to a stand part way in (does this apply on the JLE at PED stations?). This requirement in particular is quite destructive. This has existed as a requirement (though not always expressed as such!) since the early Victoria line days, though it was possibly less noticeable there. It certainly exists on the Central line. It’s certainly more noticeable with TBTC / CBTC, partly as the train will manage to close up quite closely but then be brought to a stand, often for what seems like an age (far longer than one would have waited for the inner home signal to clear in olden times), then the train has to restart from a stand. Whereas with signals the inner home would normally clear with the train still moving, which if the driver was responsive would normally result in a fairly quick re-occupation. The final speed-control signalling installation at Oval was wonderful if used as designed, but the problem latterly was this meant getting very close to anticipating signal clearance, which had become increasingly unacceptable. So you’d only really get to see it working if the train in front was detained in the platform for some reason. This particular location could certainly deliver a better reoccupation time then compared to now. |
|
|
|
Post by jimbo on Oct 13, 2021 1:43:20 GMT
I think so. While it's been a few years I'm fairly sure you couldn't get two trains in the same platform - I'll recheck my old notes. It did happen, sort of. If a train was right up the back of another, the home signal would clear from red to white and the second train would follow the first quite closely, relying on nothing out of course happening to slow or stop the first. If something did happen then the second train would sooner or later encounter a track circuit with no code and get tripped, which if the first train was “pulled down” leaving the platform could well result in two trains in a platform length. Needless to say in the final years of the old Vic signalling this exact scenario happened, which resulted in much jumping up and down from the RMT, and of course no one able to explain what had *actually* happened! This did happen with multi-home conventional signalling, intended to bring trains close together to improve platform reoccupation. As a train departed, the following train received progressively clearing home signals, but the final one had no signal alongside its trainstop. If a departing train stopped in an unusual position, the following train could be tripped to a stand part-way down the platform. So the original Victoria line signalling provided an auto version of this. |
|
Tom
Administrator
Signalfel?
Posts: 4,196
|
Post by Tom on Oct 13, 2021 20:56:05 GMT
[It did happen, sort of. If a train was right up the back of another, the home signal would clear from red to white and the second train would follow the first quite closely, relying on nothing out of course happening to slow or stop the first. If something did happen then the second train would sooner or later encounter a track circuit with no code and get tripped, which if the first train was “pulled down” leaving the platform could well result in two trains in a platform length. Needless to say in the final years of the old Vic signalling this exact scenario happened, which resulted in much jumping up and down from the RMT, and of course no one able to explain what had *actually* happened! This was exactly the detail I needed to check! There were several overlaps throughout the platform length, starting at each track circuit boundary, with no Headway Posts. The idea was exactly as you describe, to allow a second train to closely follow the first based on the assumption that the first wouldn't stop for any reason. From memory, the setup was designed so that the code would step up for the second train about three seconds before it passed over the blockjoint - in other words the second train was always about three seconds away from a trip. |
|
|
|
Post by spsmiler on Oct 13, 2021 22:41:12 GMT
This did happen with multi-home conventional signalling, intended to bring trains close together to improve platform reoccupation. As a train departed, the following train received progressively clearing home signals, but the final one had no signal alongside its trainstop. If a departing train stopped in an unusual position, the following train could be tripped to a stand part-way down the platform. So the original Victoria line signalling provided an auto version of this. I can remember seeing tripcocks part way along the platform - and seeing / hearing them lowering as the train approached. Liverpool Street Central line westbound had that type of multi-home signalling; as a schoolboy I used to listen out for the the hiss of air as the tripcocks raised as the back of the train was passing over them. I almost always travelled in the last car where I could watch the guard at work. But, re: the Victoria line I seem to recall that the sight of two moving trains partially in the one platform so upset the passengers on the platform (who feared that there was about to be a crash) that LT changed the signalling to prevent this from happening. |
|
DWS
every second count's
Posts: 2,487
|
Post by DWS on Oct 14, 2021 19:44:21 GMT
This did happen with multi-home conventional signalling, intended to bring trains close together to improve platform reoccupation. As a train departed, the following train received progressively clearing home signals, but the final one had no signal alongside its trainstop. If a departing train stopped in an unusual position, the following train could be tripped to a stand part-way down the platform. So the original Victoria line signalling provided an auto version of this. I can remember seeing tripcocks part way along the platform - and seeing / hearing them lowering as the train approached. Liverpool Street Central line westbound had that type of multi-home signalling; as a schoolboy I used to listen out for the the hiss of air as the tripcocks raised as the back of the train was passing over them. I almost always travelled in the last car where I could watch the guard at work. But, re: the Victoria line I seem to recall that the sight of two moving trains partially in the one platform so upset the passengers on the platform (who feared that there was about to be a crash) that LT changed the signalling to prevent this from happening. Spsmiler, the hiss of air you listen to on the Central Line was from a trainstop on the track. Tripcocks were on the leading bogie and rear bogie of a train . |
|
|
|
Post by spsmiler on Oct 14, 2021 23:21:19 GMT
I can remember seeing tripcocks part way along the platform - and seeing / hearing them lowering as the train approached. Liverpool Street Central line westbound had that type of multi-home signalling; as a schoolboy I used to listen out for the the hiss of air as the tripcocks raised as the back of the train was passing over them. I almost always travelled in the last car where I could watch the guard at work. But, re: the Victoria line I seem to recall that the sight of two moving trains partially in the one platform so upset the passengers on the platform (who feared that there was about to be a crash) that LT changed the signalling to prevent this from happening. Spsmiler, the hiss of air you listen to on the Central Line was from a trainstop on the track. Tripcocks were on the leading bogie and rear bogie of a train . ooops! late at night... yes I was thinking of the trainstops ... which interact with the tripcocks on the trains if a signal was passed at danger! |
|
|
|
Post by transportizm on Oct 17, 2021 17:47:48 GMT
Hi there,
I am just wondering when SMA5 will be commissioned. Some people are saying November and some people are saying January. Which date is this?
|
|
rincew1nd
Administrator
Junior Under-wizzard of quiz
Posts: 10,286
|
Post by rincew1nd on Oct 17, 2021 18:11:39 GMT
I am just wondering when SMA5 will be commissioned. Some people are saying November and some people are saying January. Which date is this? Yes. |
|
|
|
Post by transportizm on Oct 17, 2021 18:16:00 GMT
Is it November or January???
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Oct 17, 2021 18:37:14 GMT
10th April latest date
|
|
rincew1nd
Administrator
Junior Under-wizzard of quiz
Posts: 10,286
|
Post by rincew1nd on Oct 17, 2021 18:50:23 GMT
What year?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Oct 17, 2021 19:38:27 GMT
|
|
|
|
Post by transportizm on Oct 17, 2021 20:39:24 GMT
That is very late, I wonder why they already put the DMIs at Earl's Court already. |
|
Tom
Administrator
Signalfel?
Posts: 4,196
|
Post by Tom on Oct 17, 2021 21:50:31 GMT
It was supposed to be 6/7 November, and the DMIs were installed in readiness for that date.
|
|
|
|
Post by d7666 on Oct 18, 2021 14:05:25 GMT
That is very late, I wonder why they already put the DMIs at Earl's Court already. Believe it or not, we do actually try to install things before commissioning dates. Just because that date itself may slide back, there is no reason to slide everything else that leads up to it. |
|
|
|
Post by transportizm on Oct 19, 2021 15:54:43 GMT
We'll see if it is the 6/7 November if not it will be most likely January. I don't believe it would be April because that is very far away.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Oct 19, 2021 18:24:17 GMT
We'll see if it is the 6/7 November if not it will be most likely January. I don't believe it would be April because that is very far away. Want to put some money to your quote? My money is April if not beyond |
|
|
|
Post by spsmiler on Oct 19, 2021 19:17:09 GMT
I'm not putting money on anything as I'm not a betting person.
But I am curious to know just how serious / severe are the issues preventing progressing according to the planned time-frame?
|
|
