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Post by Deleted on Sept 15, 2019 11:38:47 GMT
I’ve had a quick look but can’t find them, can somebody post the SMA please? I will save them this time.
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Chris M
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Post by Chris M on Sept 15, 2019 11:56:37 GMT
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Post by ijmad on Sept 15, 2019 15:49:14 GMT
Is the Kensington Olympia branch part of SMA5, or is it not being modernised? Diagram isn't entirely clear one way or another.
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Colin
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Post by Colin on Sept 15, 2019 16:11:08 GMT
Olympia is indeed part of SMA5
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Post by philthetube on Sept 16, 2019 10:24:43 GMT
I would love to know how much more power the trains use when running with the new signalling system, it is noticeable that there is a lot more accelerating and brakeing with the new system then the old, especially going down from Finchley Rd. to Baker St.
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Post by ijmad on Sept 16, 2019 21:15:04 GMT
Slightly OT, but looking at the SMA diagram, it seems resignalling the Piccadilly with anything other than Seltrac would be insane given the overlaps in West London. Not only from a interoperability point of view, but also from a timetabling point of view to make the Picc trains squeeze in to the right paths between both the District and Met trains. I wonder if it will go out to tender and whether any other system will be able to claim it'll produce a working mixed system. I'm almost surprised the upgrade project wasn't the SSR + Piccadilly.
I know there's an idea to give over Ealing Broadway to the Picc to make things a bit simpler in time, but not running both the Met and Picc to Uxbridge seems like a pipe dream given there won't ever be enough trains per hour on the Met to ever make this sensible.
Then again, those compromise height platforms are going to have to be dealt with somehow at some future date when the accessibility legislation is once again tightened and level access is required across the network.
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Post by Deleted on Sept 16, 2019 21:33:38 GMT
Hence there is a rumour the 4 track past Barons Court (SMA5) will not get upgraded until the Picc has its own upgrade, again its a Rumour
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Post by scheduler on Sept 17, 2019 23:40:38 GMT
Picc and District signalling will operate in some sort of combined manner, with one over the top of the other - no idea of the technical details, but I believe the intention is that when the shared track sections come on, both Picc and Districts or Mets will be able to operate on the same tracks under different signalling systems!
I do know that the Picc's new control system - PICU will allow timings to a quarter minute precision, which is of course the case with 4LM new signalling.
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Post by Deleted on Sept 18, 2019 0:51:16 GMT
Thales call them inter operable areas but we call it underlay and overlay.
I always get them muddled up but one is where the existing signalling controls what CBTC will do and the other is where CBTC controls the existing signalling.
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Post by jimbo on Sept 18, 2019 1:34:16 GMT
I would love to know how much more power the trains use when running with the new signalling system, it is noticeable that there is a lot more accelerating and brakeing with the new system then the old, especially going down from Finchley Rd. to Baker St. I can tell you that the Victoria line upgrade provides lessons, with its overall power consumption lowered from pre-upgrade times, with composite conductor rails, reduced sectionalisation, inverting sub-stations, and 750V nominal supply voltage (1,000V, 6000A regenerative braking capability). |
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Post by goldenarrow on Sept 18, 2019 5:48:18 GMT
Thales call them inter operable areas but we call it underlay and overlay. I always get them muddled up but one is where the existing signalling controls what CBTC will do and the other is where CBTC controls the existing signalling. Underlay is where CBTC controls the fixed block signalling and Overlay is where fixed block signalling controls CBTC. Metropolitan interoperable’s use underlay whilst the Districts are overlay. |
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Post by jimbo on Sept 18, 2019 7:51:31 GMT
Overlay includes west of Chiswick Park, as well as Network Rail lines.
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Post by ijmad on Sept 18, 2019 8:22:14 GMT
What's happened this morning? Another non-communicating train?
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Post by norbitonflyer on Sept 18, 2019 10:20:14 GMT
Metropolitan interoperable’s use underlay whilst the Districts are overlay. Why two different systems? |
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Post by trt on Sept 18, 2019 11:14:13 GMT
Metropolitan interoperable’s use underlay whilst the Districts are overlay. Why two different systems? Presumably something to do with train detection. But surely if a fixed-block section is occupied by a non-CBTC train, then the fixed-block signalling must be telling the CBTC controller something. Curious about how that would work. I await a reply from someone in the know! |
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Post by ninefoot on Sept 18, 2019 11:30:14 GMT
Metropolitan interoperable’s use underlay whilst the Districts are overlay. Why two different systems? The two interoperable areas are quite different. The Met involves Chiltern Railways running over LU infrastructure which is signalled from Hammersmith. The District involves LU trains running over Network Rail infrastructure signalled by NR. There are a lot of complexities but hopefully that helps. Neil |
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Post by ijmad on Sept 18, 2019 14:09:58 GMT
I can understand how an overlay system works, very roughly I guess you'd feed the CBTC system fixed blocks the same size and positions as your fixed traditional aspect signalling blocks and have a set a target speed of 0 for red, slow for yellow and line speed for green.
What I don't quite get yet is the underlay system, as it would seem the typical commands sent to a train running under full CBTC (target speed and braking curve information) would be difficult to communicate to a driver just with traditional aspect signalling. Perhaps more info on this will become apparent in due course.
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Post by goldenarrow on Sept 18, 2019 17:36:36 GMT
Why two different systems? Presumably something to do with train detection. But surely if a fixed-block section is occupied by a non-CBTC train, then the fixed-block signalling must be telling the CBTC controller something. Curious about how that would work. I await a reply from someone in the know! As ijmad correctly inferred, the Vehicle On Board Computer (VOBC) would issue/receive commands to stop at the hold point which in the scenario you describe would be the auxiliary signals themselves. Once the section immediately ahead is clear, the hold point moves accordingly. What I don't quite get yet is the underlay system, as it would seem the typical commands sent to a train running under full CBTC (target speed and braking curve information) would be difficult to communicate to a driver just with traditional aspect signalling. Perhaps more info on this will become apparent in due course. CBTC fitted trains will not need to rely on auxiliary signals when traversing underlaid or overlaid signalled sections of track as they will not transition out. Only non CBTC equipped stock will need to adhere to them under normal running conditions. |
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Post by norbitonflyer on Sept 18, 2019 18:34:12 GMT
Why two different systems? The two interoperable areas are quite different. The Met involves Chiltern Railways running over LU infrastructure which is signalled from Hammersmith. The District involves LU trains running over Network Rail infrastructure signalled by NR. There are a lot of complexities but hopefully that helps. Neil Very clear, thanks. I had overlooked the NR trains, as I was focussing on the other LU trains which will be running on SSR tracks, which are of course the same (1973 stock) on both the Met and the District. Will the Uxbridge branch and the Hammersmith-Ealing Common section use underlay, overlay, or both? |
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Post by MoreToJack on Sept 18, 2019 18:38:15 GMT
Uxbridge is due to be underlay.
Hammersmith to east of Acton Town (excluding Richmond) will be full CBTC with no underlay or overlay and fully segregated running.
Acton Town to Ealing Common... I can never remember.
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Post by goldenarrow on Sept 18, 2019 18:56:15 GMT
With some help from Dstock7080 , I have compiled a couple of speed comparison graphs for the newly commissioned SMA 2 between Finchley Road and Baker St. Graphs have been sectioned by the approximate location of CBTC hold points. The 1st graph shows the Southbound. The average speed under manual operation was 28 mph. Average speed under CBTC is 30 mph. That is an approximate uplift of 7%.  The 2nd graph shows the Northbound. The average speed under manual operation was 26 mph. The average speed under CBTC is 29. That is an approximate uplift of 12%.  |
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Post by jimbo on Sept 18, 2019 20:25:36 GMT
LU own Met lines and can fully resignal to Amersham and Uxbridge with CBTC as rest of sub-surface lines, but then add colour light signals for non-equipped trains, i.e. Picc and National Rail. This means Met trains can follow closely with effective moving block, but non-equipped trains require normal spacing. On District Richmond and Wimbledon lines the current signalling remains, but CBTC added to allow trains to 'see' the signals, requiring current train spacing. West of Chiswick Park the current signalling remains with CBTC fitted in this way for District trains, since this is primarily Picc territory by service frequency and will be resignalled with that line. With aim for 27tph off-peak on that line, inter-working fast and slow lines to Hammersmith isn't practical, and is to be abandoned to simplify resignalling of both lines.
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Post by roman80 on Sept 18, 2019 21:59:24 GMT
Where on the Wimbledon branch will be the point of cutover between full CBTC and overlay?
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Tom
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Post by Tom on Sept 18, 2019 22:03:01 GMT
Where on the Wimbledon branch will be the point of cutover between full CBTC and overlay? I would imagine the first signal will be W355 which is between Putney Bridge and East Putney, based on the current intention not to alter the panel layout at Wimbledon Signalling Centre. |
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Colin
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Post by Colin on Sept 19, 2019 21:36:47 GMT
What's happened this morning? Another non-communicating train? This seems to have gone unanswered........there was a couple of issues..... 1) A District train at Paddington had no movement despite being in a communicating state, so had to be moved to Edgware Road in restricted mode (limited to 10mph) 2) The bigger issue was a loss of point detection at Baker Street. Once the cause was identified, a temporary fix was put in place [that took out platform 4 for the rest of the day]. |
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Post by MoreToJack on Sept 19, 2019 22:54:01 GMT
As I mentioned in the Met thread, it is worth clarifying that the points issue was not related to CBTC and would have happened regardless of the system going live.
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Post by ijmad on Sept 20, 2019 21:51:32 GMT
Things seem to have gone a bit wonky this evening. The status screens are even using the "delays while we establish our new signalling system" again
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Post by Deleted on Sept 20, 2019 23:00:47 GMT
Faulty train I believe plus around 4pm I was stuck for about 35mins due to a suspect package at Moorgate
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Post by ijmad on Sept 21, 2019 17:59:00 GMT
Do you think that perhaps, faster rescue procedures required to deal with trains that develop CBTC faults? Or is this expected to settle down over time?
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Post by underover on Sept 21, 2019 18:55:36 GMT
Do you think that perhaps, faster rescue procedures required to deal with trains that develop CBTC faults? Or is this expected to settle down over time? It all needs to be done in a safe way, that is why it limits the speed right down to 10mph. I know on some stock, this can be cut out and over ridden, but would require permission from the controller, perhaps stop all other train movements while this move happens etc. |
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