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Post by stapler on Apr 10, 2016 15:45:30 GMT
Sorry, British
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hobbayne
RIP John Lennon and George Harrison
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Post by hobbayne on Apr 10, 2016 17:10:47 GMT
Museum sdgs is going, but will be retained at the moment until Liv St sdgs has been restored to operation.
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Post by superteacher on Apr 10, 2016 19:00:29 GMT
Museum sdgs is going, but will be retained at the moment until Liv St sdgs has been restored to operation. But didn't they plain line it last weekend? |
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Post by marri260 on Apr 10, 2016 20:02:18 GMT
Wasn't actually plain lined last weekend, just enabling works. The impression that I got was that it isn't absolutely 100% set in stone yet, but the plan as it stands is to plain line them. Certainly not the most reliable set of points on the combine!
Both Liverpool Street sidings and the scissors crossover are currently having a like for like bullhead replacement.
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Ben
fotopic... whats that?
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Post by Ben on Apr 10, 2016 21:48:41 GMT
There was a document a good few years ago about the end state track layout of the SSR, that might have been two resignalling contracts ago now! And certainly some things have changed drastically since then. It would certainly be interesting to see the current lie of the land, as it were, if such a document is out there? Presumably there will be similar documents for the other lines too when their upgrades are fixed.
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DWS
every second count's
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Post by DWS on Apr 11, 2016 8:15:18 GMT
Wasn't actually plain lined last weekend, just enabling works. The impression that I got was that it isn't absolutely 100% set in stone yet, but the plan as it stands is to plain line them. Certainly not the most reliable set of points on the combine! Both Liverpool Street sidings and the scissors crossover are currently having a like for like bullhead replacement. Is there some reason why these points can not be relayed with flat bottom rail ? |
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Deleted
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Post by Deleted on Apr 11, 2016 13:09:47 GMT
Depends what type of points they are
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Post by bananaman on Apr 11, 2016 16:02:05 GMT
Depends what type of points they are Standard Four Foots, if you include wide-to-gauge single switches as being standard |
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Deleted
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Post by Deleted on Apr 11, 2016 20:47:30 GMT
Only a couple of mods to get them to work with FB rail then
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Post by Tomcakes on Apr 12, 2016 19:01:09 GMT
The disused platform saga as nothing to do with the upgrade. The escalators which go down to the Picc are in desperate need for refurbishment and to allow access to the Picc the stairs in the middle of the District & Circle platforms will be used as a alternative normal route. The LFB had raised concerns on the vast of people who would need to be evacuated in case of a emergency. LU have come up with a idea to reinstate the E/B disused platform to try and ease congestion and have another emergency exit at the other end of the station via some temporary stairs similar to what happened at Sloane Square a few backs when the Chelsea flower show was on. It is difficult enough as it is especially when an escalator is broken (regularly). The station is far too small for the number of people who need to use it, especially when children and buggies are brought into the equation. |
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Post by spsmiler on Apr 12, 2016 22:21:09 GMT
The disused platform saga as nothing to do with the upgrade. The escalators which go down to the Picc are in desperate need for refurbishment and to allow access to the Picc the stairs in the middle of the District & Circle platforms will be used as a alternative normal route. The LFB had raised concerns on the vast of people who would need to be evacuated in case of a emergency. LU have come up with a idea to reinstate the E/B disused platform to try and ease congestion and have another emergency exit at the other end of the station via some temporary stairs similar to what happened at Sloane Square a few backs when the Chelsea flower show was on. It is difficult enough as it is especially when an escalator is broken (regularly). The station is far too small for the number of people who need to use it, especially when children and buggies are brought into the equation. The second e/b platform will still be useful, but on its own might not be enough. Maybe it would be safer to temporarily close the Piccadilly Line platforms, as per Paddington (Bakerloo Line) at present. Simon |
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Chris M
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Post by Chris M on Apr 12, 2016 22:54:33 GMT
Could Gloucester Road and Earl's Court cope with the extra interchange passengers? Could the SSR platforms at South Kensington cope with the Picc line pax as well as their normal loads?
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Deleted
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Post by Deleted on Apr 13, 2016 6:00:42 GMT
Could Gloucester Road and Earl's Court cope with the extra interchange passengers? Could the SSR platforms at South Kensington cope with the Picc line pax as well as their normal loads? Gloucester Road would not for sure and Earls Court would struggle as it's currently a busy station as it is. |
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Post by superteacher on Apr 14, 2016 18:44:05 GMT
So clearly Holborn isn't needed as a reversing point . . . But it's been used a few times today after service disruptions!
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Post by spsmiler on Apr 14, 2016 23:03:55 GMT
Could Gloucester Road and Earl's Court cope with the extra interchange passengers? Could the SSR platforms at South Kensington cope with the Picc line pax as well as their normal loads? Gloucester Road would not for sure and Earls Court would struggle as it's currently a busy station as it is. But to most passengers having two alternative interchange choices is still better than the present day situation at Paddington where the 'no choice' alternative is a very busy Baker Street - and then extra trains if Paddington was your intended destination! (or for some journeys to change at Willesden Junction and West Brompton) Simon |
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Post by spsmiler on Apr 14, 2016 23:11:59 GMT
So clearly Holborn isn't needed as a reversing point . . . But it's been used a few times today after service disruptions! there is an expression used by officialdom when something is happening that is inconvenient to what they want everyone else to know about... "move along quickly please, there is nothing of note to see here..." To the passengers there is a world of difference in terminating trains at Marble Arch, Holborn and Liverpool Street. I understand that Bethnal Green was also used as a reversing point, which to passengers wanting that station was even better than Liverpool Street would have been, had it been available. Simon |
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Post by notverydeep on Apr 15, 2016 17:51:55 GMT
The case for providing or keeping facilities such as crossovers or sidings to reverse trains in an emergency is a trade-off between the likely benefits and costs of the facility. Some passengers do indeed gain a less disrupted journey than they would without the facility, but clearly the money spent on these facilities cannot be spent on other things that would benefit passengers in other ways.
The uses of emergency reversing facilities (that is those that are not used for significant numbers of scheduled trains) include:
• To allow recovery of a defective train to the closest depot or siding.
• To allow trains trapped by an incident or suspension to be reversed to continue to serve part of the line. This generally only applies to major incidents, as such interventions will dislocate crews and stock, so there is a preference to stop for a short time and then keep running as normal even with a small degree of service lateness, where the incident is expected to be resolved quickly.
• They may allow the service to be started up (or ramped down) more easily, by allowing a train to access the return route earlier than if it had to reach the end of the line terminus.
• To allow engineering vehicles to gain the other line to access a possession (or move within it).
• To allow the service to be recovered from late running following disruption by reversing short of the intended terminus, these are typically the reversing sidings or additional platforms closer to the ends of the line.
• To allow a planned closure for engineering work to take place with service maintained on an unaffected section of line. Scissors crossovers are especially valuable in this respect and it is this use that accounts for the greatest passenger benefit of ‘emergency’ reversing facilities.
But they also can have a variety of disadvantages:
• The cost of installation, renewal and ongoing maintenance.
• These facilities are more complex than plain line and fail more often, sometimes causing rather than mitigating disruption to passengers.
• Specific movements must be scheduled to use them to maintain crew knowledge and verify that they are working. This isn’t always successful and some facilities see little use where service controllers fear that they are likely to fail. These workings can take up a lot of capacity that might be used by additional through trains, for example where reversing blocks the line.
• They can reduce acceleration performance where located soon after platform ramps, as gaps in conductor rails cause some motor vehicles to stop powering briefly (although this problem doesn’t affect overhead electric or diesel trains).
• They can compromise the track alignment requiring a severe speed restriction, which will be for at least a train length, plus the length of the track affected.
In practice, it is the last two that are most damaging to the case for installing or retaining emergency reversing facilities, as the run time penalty applies to every passenger on every train, day after day. Where these are true, there is likely to be a poor case to retain the facility. A 10 second run time improvement on a link with millions of journeys a year would normally be worth spending significant sums to achieve. As modern signalling infrastructure and rolling stock become more reliable, it becomes harder to justify not realising such run time savings given the degree to which emergency reversing facilities help mitigate a very infrequent major failure. This is especially true as removal will normally lead to cost savings as well.
Signalling upgrades or the requirement to renew the point work inevitably require significant spending to keep these facilities and it is at this point that their worth will typically be investigated. An upgrade may prompt an opportunity to make savings on infrequently used crossovers, but at the same time invest in facilities that are well located and have a high reversing capacity to use during closures – again scissors crossovers, especially if these can be positioned away from where trains need to accelerate. The appraisal will take account of the proximity of alternative facilities, the further away these are the better the case for retention will be, as services during engineering work will allow more of the lines’ stations to be served.
It really won’t be the intention of those investigating the worth of keeping reversing facilities to make the life of either service controllers or passengers more difficult, but is right that these ‘bean counters’ take account of the potential trade-off between the partially mitigated impact of an infrequent failure against the potential improvements to passengers’ every day journey time - and yes cost savings that can be found and made available to other projects.
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Post by londonstuff on Apr 15, 2016 17:58:31 GMT
notverydeep I'm sure others will have questions or comments, but can I say thank you for such a thorough and interesting post looking at the other viewpoint somewhat 
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Post by patrickb on Apr 15, 2016 18:36:43 GMT
• They can compromise the track alignment requiring a severe speed restriction, which will be for at least a train length, plus the length of the track affected. Speed can effect frequency, however trains can travel closer under slower speeds, something which should be achievable with ATO. The trend today unfortunately is 'Everything needs to go faster', which achieves very little in terms of increasing capacity. |
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Deleted
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Post by Deleted on Apr 15, 2016 20:57:19 GMT
• They can compromise the track alignment requiring a severe speed restriction, which will be for at least a train length, plus the length of the track affected. Speed can effect frequency, however trains can travel closer under slower speeds, something which should be achievable with ATO. The trend today unfortunately is 'Everything needs to go faster', which achieves very little in terms of increasing capacity. Travelling slower and closer together provides shorter headways obviously but if the slower speed means the end to end run time is increased then more trains will be needed to provide the service (or more likely there wouldn't be enough trains to provide the service). Hence, London Underground measures customer journey time which balances run times, headways, train capacity and station access times. Faster trains almost always support more capacity up to a point. |
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Post by notverydeep on Apr 16, 2016 10:36:44 GMT
Speed can effect frequency, however trains can travel closer under slower speeds, something which should be achievable with ATO. The trend today unfortunately is 'Everything needs to go faster', which achieves very little in terms of increasing capacity. Travelling slower and closer together provides shorter headways obviously but if the slower speed means the end to end run time is increased then more trains will be needed to provide the service (or more likely there wouldn't be enough trains to provide the service). Hence, London Underground measures customer journey time which balances run times, headways, train capacity and station access times. Faster trains almost always support more capacity up to a point. Ideally, a departing train should only be constrained by its acceleration performance rather than track speed as this ensures that the run out time, that is the time the first train takes to reach the clearance point at which movement authority can be given to the second train to start its run into the platform, is as short as possible. It is certainly true however that a slower approach speed will allow shorter run in time. This is because a shorter overlap cam be permitted at the 'home signal' (which could be a block marker board, or in moving block terms the 'limit of movement authority') and this can be located closer to the platform. In an ATO or moving block case this is best achieved by having a 'peak time only' speed profile that the train follows through the link before the platform, rather than a line speed limit. By implementing this within the ATO, not all trains have to be slowed down because it is likely that the throughput will only be constrained at the height of the peak, when the dwell time will be longest and the shortest headway desired. At other times, shorter dwell times and / or longer planned headways will mean that it is wasteful to continue to incur the run time penalty, which is needed only at the very busiest part of the traffic day. Even at the height of the peak, some trains will inevitably be on slightly longer headways than planned and the ATO can then allow these to take advantage of the fastest run in speed, which will then aid recovery. In practice many trains could be allowed to use the faster approach, because even at the constraint stations there will be some recovery margin to allow for the variation in dwell time (that is at least some longer dwells, such as those with repeat door cycles). In terms of the impact on throughput capacity at a constraint location, emergency reversing pointwork is much more likely to impact departing trains (run out) than approaching trains (run in), unless the alignment is compromised so that additional earlier braking is needed. Constraint locations are typically those with the highest peak dwell time. |
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Post by Dstock7080 on May 5, 2016 16:54:53 GMT
British Museum siding will be decommissioned and signals removed over weekend of 21/22 May.
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Post by superteacher on May 5, 2016 18:56:29 GMT
British Museum siding will be decommissioned and signals removed over weekend of 21/22 May. Total disgrace. It's quite worrying to think that people capable of making decisions like this are in charge of railways. Proves they at willing to put cost over the running of an efficient railway. Mind you, we knew that anyway. |
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Post by superteacher on May 21, 2016 18:37:08 GMT
British Museum siding will be decommissioned and signals removed over weekend of 21/22 May. Perhaps the info should be as follows: "We are sorry for the inconvenience due to this weekend's engineering works - the work is necessary so that we can inconvenience you all further in the future when a train breaks down and blocks the line because we will have nowhere to put it . . ." |
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Post by jmm on May 21, 2016 18:58:22 GMT
The webpage message says "to allow for points renewal work at Holborn and Bank". Didn't know there were points at Bank. Also, have they had a second thought about the removal and are renewing the points instead as the message suggests?
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Post by spsmiler on May 21, 2016 19:02:35 GMT
British Museum siding will be decommissioned and signals removed over weekend of 21/22 May. Perhaps the info should be as follows: "We are sorry for the inconvenience due to this weekend's engineering works - the work is necessary so that we can inconvenience you all further in the future when a train breaks down and blocks the line because we will have nowhere to put it . . ." I wonder whether it is less costly to maintain junctions and sidings (as per here) or to pay out refunds via the customer charter when delays occur? Or is it that since the costs are allocated to different "financial pots" (or budgets) so therefore this is not seen as part of the decision-making process? Simon |
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Deleted
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Post by Deleted on May 21, 2016 19:32:38 GMT
The webpage message says "to allow for points renewal work at Holborn and Bank". Didn't know there were points at Bank. Also, have they had a second thought about the removal and are renewing the points instead as the message suggests? I noticed that There aren't any points at Bank. I think there used to be. You can still see a gap in the tunnel walls just east of the station where I presume the points used to cross from one track to the other, but there aren't any points there anymore. I guess the message is referring to the trailing crossover just west of Liverpool Street station, but that hardly qualifies as at Bank to me  |
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Post by superteacher on May 21, 2016 19:59:55 GMT
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