Ben
fotopic... whats that?
Posts: 4,282
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Post by Ben on Feb 23, 2016 14:25:51 GMT
@mrfs will be able to comment better than I, but comparison of past running times and frequencies to that being touted as only available with ATO does not show the latter in a particularly superior position. Depending on how far back you go, other issues creep in giving a material advantage to the past; shorter trains and no requirement for Moorgate control/terminal protection. (Why is Moorgate control needed to the same degree as in manual driving under ATO, incidentally? Why is it necessary?)
The problem seems to be that there is a mismatch between what modern driving and signalling systems are designed to provide and what experience shows is possible/works best under manual driving and signalling. Does one try to emulate and improve on the imperfect human system, or try to develop something entirely new from first principals? How does one bridge the gap between the two without resorting to clumsy metrics or myriad compromises and get outs? Additional research into technology and software is likely needed. And soon, whilst there are still manually driven trains to compare against.
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North End
Beneath Newington Causeway
Posts: 1,769
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Post by North End on Mar 2, 2016 23:43:30 GMT
I thought the ditching of Westinghouse was one of the first things LU did when they got hold of Metronet. Regarding the NCTs, the whole problem is that trains *don't* brake heavily in the open, because the system is set to the minimum brake rate. Any heavy braking is basically likely to produce a NCT if the railhead is less than perfect. The use of low brake rates gives needlessly extended journey times, which is bad for the passenger. It's just about tolerable on the Northern as only a relatively small amount of the line is in the open, and the effect has been a little masked by the fact the line previously had a low line-speed compared to other lines. However the Jubilee from Stanmore to Finchley Road is a painful experience, and a journey like Upminster to the centre will become probably unacceptably long if a solution isn't found to this issue. And of course there are numerous reasons why a train might need to emergency brake, eg a hazard on the line ahead or a PEA pulled leaving a station - these everyday scenarios shouldn't cause the delay of an NCT. Personally, observing the routing of trains via TBTC, how trains follow each other at certain locations, and observing the working at key junctions, I have doubts the Northern will be able to reliably run much more than it does at present. Platform re-occupation times at some key locations are pretty poor as things stand at present. The glitzy promo videos from Thales and Alcatel before them are somewhat different to reality. You might well be right on the Metronet / LU thing. Either way that and the Cityflo decisions have undoubtedly delayed the SSR upgrade. The Jubilee line is not generally on minimum brake rates and rarely has NCT problems due to slip /slide so whatever you think is painful about the experience on that line is unlikely to be brake rate issues. But, as I said, more work needed. Don't forget there are two more planned software builds for Northern - one this weekend hopefully - so still further improvements to come including changes to speed restriction warnings on the TOD which have been tested with one of the PM experts on the Northern i believe. I see the Seltrac adhesion/NCT flaw has well and truly bitten today - Northern Line up the wall all afternoon and through today's evening peak due to a couple of EB/NCT incidents around lunchtime. Frankly it's unacceptable for nothing more than a bit of rain on a railhead to cause such disruption. It doesn't help that the system simply doesn't push trains through the junctions nearly as well as the old signalling. I turned up at Camden southbound with 4 trains shown expected within 4 minutes. Whereas under the old signalling trains would have come through pretty quickly behind each other, under Seltrac the re-occupation time between each train was frankly pitiful. These pinch-points really show up when the service is disrupted. I'm afraid the new software still has plenty of issues. Just as we've become accustomed from this system, some of the issues raised have indeed been improved (I wouldn't say sorted, for example the target speed still blips with no warning between Oval and Stockwell, just not as much as before), however fresh issues have cropped up in new places. New issues with target speed dropping with no warning, for example at Stockwell and Tooting Broadway, neither location previously having given problems. I wouldn't be surprised if it could be some kind of new software bug with target speed dropping erratically that seems to be causing so many troubles at Finchley Central - I'm dubious that it's to do with adhesion or friction braking as the trains are already on minimum brake rate so should be not sliding unless an EB occurs for some other reason. Must admit if I were making the decisions I would *not* be buying more of this product. It's extremely unfortunate it's currently the only product on the table. This will be even more of an issue when the NTFL lines go to tender - not only will there be little other option, but LU will have little bargaining power over price either.
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Post by phoenixcronin on Mar 8, 2016 19:08:14 GMT
A while back I came across a document/pdf which amongst other things had a map of all the Migration Areas and the expected time that they would go "live". However I have since forgotten where it came from, and can no longer find it?
Would someone be kind enough to link it?
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Deleted
Deleted Member
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Post by Deleted on Mar 14, 2016 21:08:50 GMT
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Deleted
Deleted Member
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Post by Deleted on Mar 14, 2016 21:12:42 GMT
A while back I came across a document/pdf which amongst other things had a map of all the Migration Areas and the expected time that they would go "live". However I have since forgotten where it came from, and can no longer find it? Would someone be kind enough to link it? There's a copy on the tfl website at the end of this linked document
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Post by phoenixcronin on Mar 14, 2016 21:20:00 GMT
Cheers!
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Post by londonstuff on Mar 18, 2016 23:23:34 GMT
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DWS
every second count's
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Post by DWS on Mar 19, 2016 8:21:20 GMT
The test track is at the Railway Innovation and Development Centre (Melton) formerly known as the Old Dalby Test Track.
Thales's have been running S stock trains in Automatic Train Operation mode since 26 November 2015 only a few months after signing the 4LM contract.
This is a Third generation SelTrac Intergrated Solution which builds on the second generation system that is used on the Northern Line, Jubilee Line and Docklands Light Railway.
The main changes are this a radio based communications with transponder based positioning . No cable loops on the track as on the Northern and Jubilee lines. Axle counters are still used in the system.
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Deleted
Deleted Member
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Post by Deleted on Mar 19, 2016 16:23:21 GMT
Thanks. Its a lot shorter piece than was intended - was supposed to have interviews etc as well. Good progress being made at the test track. I went up for a look yesterday. Currently the train is running at up to 35kph with an early software version. In the next few weeks the software will be updated and the speed will increase to 100kph.
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Post by Dstock7080 on Mar 19, 2016 16:46:02 GMT
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Post by spsmiler on May 11, 2016 13:14:43 GMT
You might well be right on the Metronet / LU thing. Either way that and the Cityflo decisions have undoubtedly delayed the SSR upgrade. The Jubilee line is not generally on minimum brake rates and rarely has NCT problems due to slip /slide so whatever you think is painful about the experience on that line is unlikely to be brake rate issues. But, as I said, more work needed. Don't forget there are two more planned software builds for Northern - one this weekend hopefully - so still further improvements to come including changes to speed restriction warnings on the TOD which have been tested with one of the PM experts on the Northern i believe. I see the Seltrac adhesion/NCT flaw has well and truly bitten today - Northern Line up the wall all afternoon and through today's evening peak due to a couple of EB/NCT incidents around lunchtime. Frankly it's unacceptable for nothing more than a bit of rain on a railhead to cause such disruption. It doesn't help that the system simply doesn't push trains through the junctions nearly as well as the old signalling. I turned up at Camden southbound with 4 trains shown expected within 4 minutes. Whereas under the old signalling trains would have come through pretty quickly behind each other, under Seltrac the re-occupation time between each train was frankly pitiful. These pinch-points really show up when the service is disrupted. I'm afraid the new software still has plenty of issues. Just as we've become accustomed from this system, some of the issues raised have indeed been improved (I wouldn't say sorted, for example the target speed still blips with no warning between Oval and Stockwell, just not as much as before), however fresh issues have cropped up in new places. New issues with target speed dropping with no warning, for example at Stockwell and Tooting Broadway, neither location previously having given problems. I wouldn't be surprised if it could be some kind of new software bug with target speed dropping erratically that seems to be causing so many troubles at Finchley Central - I'm dubious that it's to do with adhesion or friction braking as the trains are already on minimum brake rate so should be not sliding unless an EB occurs for some other reason. Must admit if I were making the decisions I would *not* be buying more of this product. It's extremely unfortunate it's currently the only product on the table. This will be even more of an issue when the NTFL lines go to tender - not only will there be little other option, but LU will have little bargaining power over price either. On the topic of going NCT when braking because of wet rails, I saw thie article linked below at Wikipedia which is about low adhesion, slipping and sliding and it made me wonder, surely modern Underground trains (I'm especially thinking of 1995, 1996, S stocks) have the WSP - wheel slide protection which the article talks about? en.wikipedia.org/wiki/Wheel_slide_protectionSimon
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North End
Beneath Newington Causeway
Posts: 1,769
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Post by North End on May 11, 2016 14:57:31 GMT
I see the Seltrac adhesion/NCT flaw has well and truly bitten today - Northern Line up the wall all afternoon and through today's evening peak due to a couple of EB/NCT incidents around lunchtime. Frankly it's unacceptable for nothing more than a bit of rain on a railhead to cause such disruption. It doesn't help that the system simply doesn't push trains through the junctions nearly as well as the old signalling. I turned up at Camden southbound with 4 trains shown expected within 4 minutes. Whereas under the old signalling trains would have come through pretty quickly behind each other, under Seltrac the re-occupation time between each train was frankly pitiful. These pinch-points really show up when the service is disrupted. I'm afraid the new software still has plenty of issues. Just as we've become accustomed from this system, some of the issues raised have indeed been improved (I wouldn't say sorted, for example the target speed still blips with no warning between Oval and Stockwell, just not as much as before), however fresh issues have cropped up in new places. New issues with target speed dropping with no warning, for example at Stockwell and Tooting Broadway, neither location previously having given problems. I wouldn't be surprised if it could be some kind of new software bug with target speed dropping erratically that seems to be causing so many troubles at Finchley Central - I'm dubious that it's to do with adhesion or friction braking as the trains are already on minimum brake rate so should be not sliding unless an EB occurs for some other reason. Must admit if I were making the decisions I would *not* be buying more of this product. It's extremely unfortunate it's currently the only product on the table. This will be even more of an issue when the NTFL lines go to tender - not only will there be little other option, but LU will have little bargaining power over price either. On the topic of going NCT when braking because of wet rails, I saw thie article linked below at Wikipedia which is about low adhesion, slipping and sliding and it made me wonder, surely modern Underground trains (I'm especially thinking of 1995, 1996, S stocks) have the WSP - wheel slide protection which the article talks about? en.wikipedia.org/wiki/Wheel_slide_protectionSimon Yes, all the stocks you describe have WSP. Whilst it definitely helps (remember how badly the A stock fleet suffered with flats every autumn?), it can only go so far to overcoming bad adhesion. It doesn't guarantee a train won't slide - it just helps reduce the risk, and attempts to stop the train sooner than would have been the case on a non-WSP train.
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Post by 100andthirty on May 11, 2016 19:49:38 GMT
S stock is being fitted with automatic sanders. They will automatically deliver sand in response with WSP activity. Sand does improve adhesion.
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Deleted
Deleted Member
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Post by Deleted on May 11, 2016 20:19:36 GMT
Also very abrasive sand when used can shorten the wheel profile life expectancy as its more prone to leave flats
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Post by spsmiler on May 14, 2016 22:49:23 GMT
Thanks
Simon
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Post by flippyff on Jun 7, 2016 11:36:39 GMT
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Post by londonstuff on Jun 7, 2016 12:25:41 GMT
I think it's probably okay here for now.
Does anyone know what work has actually started to take place between Hammersmith and Edgware Road?
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