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Post by Dstock7080 on Sept 4, 2021 4:39:00 GMT
Kennington-Battersea shuttle trains will be double-staffed
New distances/times:
Kennington and Nine Elms 2.10km: NB 2¼min, SB 2¼min
Nine Elms and Battersea Power Station 1.04km: NB 2¼min, SB 2¼min
Passenger services to/from Battersea commerce 20 September 2021
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Post by jimbo on Sept 4, 2021 5:04:20 GMT
The Morden branch was promised 32tph with resignalling back in 2014! After 7 more years, it can only get to 31tph. Only a 3% uplift after all on what was the busiest section of tube line!
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North End
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Post by North End on Sept 4, 2021 6:50:17 GMT
The Morden branch was promised 32tph with resignalling back in 2014! After 7 more years, it can only get to 31tph. Only a 3% uplift after all on what was the busiest section of tube line! Ditto the entire line has been running under a 50 mph temporary speed restriction since 2013, though to be fair this is more to do with the trains than the signalling as such. I know 60 mph is still the aspiration, but no idea when it’s likely to be achieved. There have been a few speed uplifts recently - trains come into a few more platforms at full brake rate, and a few curves have had speed lifted (for example coming into Archway SB). |
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Post by d7666 on Sept 4, 2021 11:54:18 GMT
The Morden branch was promised 32tph with resignalling back in 2014! After 7 more years, it can only get to 31tph. Only a 3% uplift after all on what was the busiest section of tube line! Was 32 TPH ever promised, in public, officially, as a timetabled, train service level ? ISTR the figure of 32 TPH was presented as the technical capability, the maximum achievable steady state capacity of TBTC. Which is not the same thing. Its' like the Central Line; read different sources and you can find any figure from 28 through 30-32 to 35 TPH, and different people citing different figures for different reasons. There are big big differences between the absolute minimum burst mode headway (i.e. during service recovery), maximum line wide state (i.e. with the core at maximum), and the normal practical achievable workable headway. Also, don't forget any figures that were quoted in 2014 would have been based on planning and simulation done in the mid-2000s. Dwell times have increased on all lines (pre covid obviously) because ridership was up on all lines. 32 TPH is 112.5 sec headway; 31 TPH is 116.1 sec headway. You only need one station to add 3.5 secs dwell to every peak train, or 7 stations to add 0.5 sec to RIRO, and you've lost 1 train per hour path. |
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vincenture
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Post by vincenture on Sept 4, 2021 18:19:01 GMT
The Jubilee maxspeed is currently ard 55mph, can't the Northern do so too?
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Tom
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Post by Tom on Sept 4, 2021 21:56:29 GMT
Track quality and alignment are two factors which would influence whether or not the Northern could achieve 55mph (more accurately 88km/h), but they're not the only two.
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Tom
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Post by Tom on Sept 4, 2021 21:59:02 GMT
Its' like the Central Line; read different sources and you can find any figure from 28 through 30-32 to 35 TPH, and different people citing different figures for different reasons. The original contractual requirement for the Central line resignalling was 36tph. I think most parties agreed it was not going to be achievable quite early on, the aim was then 33tph but I'm not sure even that has been realised? |
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North End
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Post by North End on Sept 4, 2021 23:45:14 GMT
Track quality and alignment are two factors which would influence whether or not the Northern could achieve 55mph (more accurately 88km/h), but they're not the only two. The reason for the TSR is the issue of the emergency brake performance of the 95 stock not being to spec, which in turn is believed to be due to glazing of the brake blocks. There’s a software modification been done recently so that some stops are being done in friction braking, as happens on the S stock. Of interest, given the similarity between the stocks it’s surprising this doesn’t appear to be an issue on the 96 stock as well, though of course although the two stocks are outwardly similar there are differences under the skin so that could be something to do with it. Most drivers would say that 95 stock emergency braking has always been rather mediocre, so perhaps none of this should be a surprise. From what I gather the speed profile for parts of the Northern has allowed for 60 mph since TBTC came in, but has always had a 50 mph ceiling superimposed on it pending the relevant assurance being achieved. It was the attempting to carry out that assurance which brought the brake performance issue to light. 60 mph was supposed to have come in for a previous timetable, but it never happened. |
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Post by d7666 on Sept 5, 2021 13:34:50 GMT
Its' like the Central Line; read different sources and you can find any figure from 28 through 30-32 to 35 TPH, and different people citing different figures for different reasons. The original contractual requirement for the Central line resignalling was 36tph. I think most parties agreed it was not going to be achievable quite early on, the aim was then 33tph but I'm not sure even that has been realised? Where I typed there 35 I couldn't remember if it was 35 or 36, and, ISTR this particular value was debated in DD some time ago, but I could not find it. But I'll say again, 36 TPH contracted or declared capability of any signalling system is not the same as telling the public "we are going to run a timetabled service of 36 trains per hour" - because the latter means a sustained peaks service, implies for 3 hours in the core a.m. peak and again 3 hours in p.m. peak, both roads in each case. This was the point I was trying to make for the Northern to try and keep this on thread topic. The timetable people always told me the practical Central capacity is around 32-33 TPH, and, AIUI, from THEIR planning rules view, the global throttle is the eastbound east of Liverpool Street. The problem is, to sustain a high TPH in each direction for 3 hours, you can't have one throttle on one one road, else the whole collapses. OK you could twiddle track circuits and go codes and block marker boards and sort that section out, but then the next most restricted area becomes the next throttle. When I was working with the Wood Lane control system, there was a timetable that came in years mid 201x that gave a 34 TPH burst for a very brief period - about 25 min, on the westbound only, in the a.m. peak. It came in about 12-18 months before the Victoria self trumpeted it's increased peak to 34 TPH; we went well woopey-do, we being doing that for months. The point is, that 34 TPH on the Central (I don't know if it is still there; it was something like 08:10 to 08:35 through Bank) was no way sustainable line wide, not even for one hour. IIRC dwell times were significantly up at Bond Street and Tottenham Court Road because of increasing interchange passengers between Jubilee and Northern. The latter is relevant to this thread - if the Central dwell times goes up because of interchanging to\from the Northern, then the reverse is true, the Northern will also go up. This will equalise, even if it balances in the opposite peak, but it still remains. So, for example, you only need TCR on the Northern to get say only 1 sec extra dwell time for every peak train, and you've already lost 1\3 of a TPH path, and sure to lose more secs elsewhere, hence you get 31 TPH not 32 TPH. |
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Post by d7666 on Sept 5, 2021 13:42:05 GMT
The reason for the TSR is the issue of the emergency brake performance of the 95 stock not being to spec, which in turn is believed to be due to glazing of the brake blocks. There’s a software modification been done recently so that some stops are being done in friction braking, as happens on the S stock. Of interest, given the similarity between the stocks it’s surprising this doesn’t appear to be an issue on the 96 stock as well, though of course although the two stocks are outwardly similar there are differences under the skin so that could be something to do with it. Most drivers would say that 95 stock emergency braking has always been rather mediocre, so perhaps none of this should be a surprise. From what I gather the speed profile for parts of the Northern has allowed for 60 mph since TBTC came in, but has always had a 50 mph ceiling superimposed on it pending the relevant assurance being achieved. It was the attempting to carry out that assurance which brought the brake performance issue to light. 60 mph was supposed to have come in for a previous timetable, but it never happened. That's interesting. Never heard that issue before. The power electronics on 95 and 96 stock are different, which might have explained a difference had this been dynamic braking, but if it's friction braking at fault, that's puzzling. I'll predict at the bottom of this, Occams Razor will apply, there will be something very simple and (with hindsight) obvious behind it. |
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North End
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Post by North End on Sept 5, 2021 13:57:04 GMT
The reason for the TSR is the issue of the emergency brake performance of the 95 stock not being to spec, which in turn is believed to be due to glazing of the brake blocks. There’s a software modification been done recently so that some stops are being done in friction braking, as happens on the S stock. Of interest, given the similarity between the stocks it’s surprising this doesn’t appear to be an issue on the 96 stock as well, though of course although the two stocks are outwardly similar there are differences under the skin so that could be something to do with it. Most drivers would say that 95 stock emergency braking has always been rather mediocre, so perhaps none of this should be a surprise. From what I gather the speed profile for parts of the Northern has allowed for 60 mph since TBTC came in, but has always had a 50 mph ceiling superimposed on it pending the relevant assurance being achieved. It was the attempting to carry out that assurance which brought the brake performance issue to light. 60 mph was supposed to have come in for a previous timetable, but it never happened. That's interesting. Never heard that issue before. The power electronics on 95 and 96 stock are different, which might have explained a difference had this been dynamic braking, but if it's friction braking at fault, that's puzzling. I'll predict at the bottom of this, Occams Razor will apply, there will be something very simple and (with hindsight) obvious behind it. There is one other difference between 95 and 96 stocks which does spring to mind - the 7th car on the 96 stock, which could have a bearing on things especially as it's a trailer car, which will of course alter the disposition of friction braking compared to a 6-car. |
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Post by superteacher on Sept 5, 2021 14:09:51 GMT
Back on topic please. 👍
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Post by d7666 on Sept 5, 2021 14:30:45 GMT
That's interesting. Never heard that issue before. The power electronics on 95 and 96 stock are different, which might have explained a difference had this been dynamic braking, but if it's friction braking at fault, that's puzzling. I'll predict at the bottom of this, Occams Razor will apply, there will be something very simple and (with hindsight) obvious behind it. There is one other difference between 95 and 96 stocks which does spring to mind - the 7th car on the 96 stock, which could have a bearing on things especially as it's a trailer car, which will of course alter the disposition of friction braking compared to a 6-car. Good point(s). Actually obvious ones. Occams Razor ? Self smack wrists off topic. |
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North End
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Post by North End on Sept 5, 2021 15:46:48 GMT
There is one other difference between 95 and 96 stocks which does spring to mind - the 7th car on the 96 stock, which could have a bearing on things especially as it's a trailer car, which will of course alter the disposition of friction braking compared to a 6-car. Good point(s). Actually obvious ones. Occams Razor ? Self smack wrists off topic. What I don’t know is if some or all of these 95 stock issues have been resolved in time for the 19th, when the new WTT comes in. Certainly there has been a massive amount of rail grinding on parts of the Northern recently. So who knows we might finally be up to 60 mph coinciding with Battersea opening. Certainly reducing run times has been a factor in allowing Battersea to happen without increasing the fleet size. |
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Post by capitalomnibus on Sept 5, 2021 19:05:09 GMT
Good point(s). Actually obvious ones. Occams Razor ? Self smack wrists off topic. What I don’t know is if some or all of these 95 stock issues have been resolved in time for the 19th, when the new WTT comes in. Certainly there has been a massive amount of rail grinding on parts of the Northern recently. So who knows we might finally be up to 60 mph coinciding with Battersea opening. Certainly reducing run times has been a factor in allowing Battersea to happen without increasing the fleet size. I was wondering how Battersea was achievable without getting more trains. I think that is part of the problem with Underground extensions is that sourcing extra trains is always going to be a problem as it would be no longer produced, or wait until all new stock is produced. I think this also may have been a factor with the Jubilee line extension to prematurely end the 83 stock. Its District line counterparts lasted years later, even gaining a second moquette, then a third when they were fully refurbed. |
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Post by Dstock7080 on Sept 5, 2021 20:25:50 GMT
I was wondering how Battersea was achievable without getting more trains. Trains previously sat in the Kennington loop for 5¼min, they now use this time productively by running onto Battersea Power Station, taking 4½min to get there. |
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Post by jimbo on Sept 5, 2021 20:29:24 GMT
The Morden branch was promised 32tph with resignalling back in 2014! After 7 more years, it can only get to 31tph. Only a 3% uplift after all on what was the busiest section of tube line! Was 32 TPH ever promised, in public, officially, as a timetabled, train service level ? ISTR the figure of 32 TPH was presented as the technical capability, the maximum achievable steady state capacity of TBTC. Which is not the same thing. Its' like the Central Line; read different sources and you can find any figure from 28 through 30-32 to 35 TPH, and different people citing different figures for different reasons. There are big big differences between the absolute minimum burst mode headway (i.e. during service recovery), maximum line wide state (i.e. with the core at maximum), and the normal practical achievable workable headway. Also, don't forget any figures that were quoted in 2014 would have been based on planning and simulation done in the mid-2000s. Dwell times have increased on all lines (pre covid obviously) because ridership was up on all lines. 32 TPH is 112.5 sec headway; 31 TPH is 116.1 sec headway. You only need one station to add 3.5 secs dwell to every peak train, or 7 stations to add 0.5 sec to RIRO, and you've lost 1 train per hour path. Accepting your detailed post, I still believe 32tph was the promised public service frequency on the Morden branch, but how to prove that now? The TfL site had quite some detail, but long gone! I find that the line boss back in 2008 is reported as saying “The new system will allow 32 trains or more south of Kennington, but 30 are planned initially to allow recovery time, ..” source He would have approved this report, but my notes of the meeting are that he said that the new system will allow 34 trains or more south of Kennington, but 32 are planned initially to allow recovery time. 32tph is also shown in a diagram here as the expected service from December 2014. |
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North End
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Post by North End on Sept 5, 2021 22:44:38 GMT
Was 32 TPH ever promised, in public, officially, as a timetabled, train service level ? ISTR the figure of 32 TPH was presented as the technical capability, the maximum achievable steady state capacity of TBTC. Which is not the same thing. Its' like the Central Line; read different sources and you can find any figure from 28 through 30-32 to 35 TPH, and different people citing different figures for different reasons. There are big big differences between the absolute minimum burst mode headway (i.e. during service recovery), maximum line wide state (i.e. with the core at maximum), and the normal practical achievable workable headway. Also, don't forget any figures that were quoted in 2014 would have been based on planning and simulation done in the mid-2000s. Dwell times have increased on all lines (pre covid obviously) because ridership was up on all lines. 32 TPH is 112.5 sec headway; 31 TPH is 116.1 sec headway. You only need one station to add 3.5 secs dwell to every peak train, or 7 stations to add 0.5 sec to RIRO, and you've lost 1 train per hour path. Accepting your detailed post, I still believe 32tph was the promised public service frequency on the Morden branch, but how to prove that now? The TfL site had quite some detail, but long gone! I find that the line boss back in 2008 is reported as saying “The new system will allow 32 trains or more south of Kennington, but 30 are planned initially to allow recovery time, ..” source He would have approved this report, but my notes of the meeting are that he said that the new system will allow 34 trains or more south of Kennington, but 32 are planned initially to allow recovery time. 32tph is also shown in a diagram here as the expected service from December 2014. Personal view, but I think the Northern would struggle to run much more than it does now, and especially during disruption when some of the nuances of the Thales system make themselves felt in unhelpful ways. The Vic Line seems to have had a lot more focus put into fine tuning, which to be fair is easier on a shorter and less complex line. The Northern is getting some of this fine tuning for sure, but it’s a slow process. By way of balance, the Vic project wasn’t without nuances either. The depot throat being left out of the resignalling spec by accident, and a massive price being subsequently quoted for the bi-di to Seven Sisters. As an aside, can anyone confirm what the current situation is with the Northumberland Park depot throat area? My understanding is the original interlocking frame was replaced by a Westrace interlocking, with some residual functions remaining carried out from the 1960s IMR. Does the old IMR still perform any function or is it redundant now? |
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Post by jimbo on Sept 5, 2021 23:25:42 GMT
I was wondering how Battersea was achievable without getting more trains..... It was always said that the extension would require five more trains, and that was built into its original cost. It is currently proposed to only extend half of Charing Cross branch trains there, so perhaps now only 2½ trains required. One was said to be released by more efficient maintenance procedures, which meant a new wheel lathe at Morden. The Mill Hill East shuttle train was only moving for 30% of its time, so a through service provides another 70% of a train. Tinkering of signalling, power, etc. to save a minute on line end to end run releases a train. The former stand time in the Kennington loop will instead be taken at the new terminus. |
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Post by jimbo on Sept 6, 2021 4:24:31 GMT
I have found another reference to planned 32tph service to Morden in January 2019 Underground News which summarises the Northern Line Upgrade 2 Business Case of May 2017, although the Morden branch table 2 was accidentally omitted, and published a few months later. This paper was about the plan for extra look-alike trains to boost the service beyond the resignalling upgrade. It refers to WTT58 as providing 32tph from Morden from 8 to 9am, which has been awaited since resignalling, and is now to only provide 31tph. 17 extra trains were to boost this branch to 32.8tph between 8 and 9am. However, a further order for 5 or 11 trains was still under consideration before the order was placed. It seems these could provide 33tph on current signalling, or 36tph with a further signalling upgrade on the Morden to High Barnet via Bank side.
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Post by d7666 on Sept 6, 2021 11:24:32 GMT
Was 32 TPH ever promised, in public, officially, as a timetabled, train service level ? ISTR the figure of 32 TPH was presented as the technical capability, the maximum achievable steady state capacity of TBTC. Which is not the same thing. Its' like the Central Line; read different sources and you can find any figure from 28 through 30-32 to 35 TPH, and different people citing different figures for different reasons. There are big big differences between the absolute minimum burst mode headway (i.e. during service recovery), maximum line wide state (i.e. with the core at maximum), and the normal practical achievable workable headway. Also, don't forget any figures that were quoted in 2014 would have been based on planning and simulation done in the mid-2000s. Dwell times have increased on all lines (pre covid obviously) because ridership was up on all lines. 32 TPH is 112.5 sec headway; 31 TPH is 116.1 sec headway. You only need one station to add 3.5 secs dwell to every peak train, or 7 stations to add 0.5 sec to RIRO, and you've lost 1 train per hour path. Accepting your detailed post, I still believe 32tph was the promised public service frequency on the Morden branch, but how to prove that now? The TfL site had quite some detail, but long gone! I find that the line boss back in 2008 is reported as saying “The new system will allow 32 trains or more south of Kennington, but 30 are planned initially to allow recovery time, ..” source He would have approved this report, but my notes of the meeting are that he said that the new system will allow 34 trains or more south of Kennington, but 32 are planned initially to allow recovery time. 32tph is also shown in a diagram here as the expected service from December 2014. I'd not argue with that in the sense of internal technical discussions; that info I remember from briefings and one course when I was with tub lies. But was it ever public ? One of the reasons I remember this discussion - especially the bit about 32 or 31 or 30 TPH south of Kennington and what was theoretical against actually achievable - is because one wit at the time commented that if you put a human on board to detect train motion i.e. a guard on each train to release the doors, you'd gain not only 1-2 sec after wheel stop (because that's how long equipment takes to work out that dt/dx d2t/dx2 and d3t/dx3 have all come to zero and the train really is stopped) and then add the guard opening the doors just as the train is stopping rather than after it has stopped, you gain another 1-2 sec - and if you do that with every train at every station you get two more TPH than ATO. |
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Post by t697 on Sept 6, 2021 17:33:23 GMT
... one wit at the time commented that if you put a human on board to detect train motion i.e. a guard on each train to release the doors, you'd gain not only 1-2 sec after wheel stop (because that's how long equipment takes to work out that dt/dx d2t/dx2 and d3t/dx3 have all come to zero and the train really is stopped) and then add the guard opening the doors just as the train is stopping rather than after it has stopped, you gain another 1-2 sec - and if you do that with every train at every station you get two more TPH than ATO. Or use the the 'train stopped' technique that the current Vic line system uses. A thread on here linked to a video showed the doors starting to open absolutely coincident with or a few milliseconds before the train being fully stopped. No wasted time there.
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Post by d7666 on Sept 6, 2021 20:59:33 GMT
... one wit at the time commented that if you put a human on board to detect train motion i.e. a guard on each train to release the doors, you'd gain not only 1-2 sec after wheel stop (because that's how long equipment takes to work out that dt/dx d2t/dx2 and d3t/dx3 have all come to zero and the train really is stopped) and then add the guard opening the doors just as the train is stopping rather than after it has stopped, you gain another 1-2 sec - and if you do that with every train at every station you get two more TPH than ATO. Or use the the 'train stopped' technique that the current Vic line system uses. A thread on here linked to a video showed the doors starting to open absolutely coincident with or a few milliseconds before the train being fully stopped. No wasted time there.
Have to admit while I am familiar enough with Central ATO, and TBTC and CTBC, and worked in Wood Lane, Neasden, and Hammersmith SCCs, the Vic line ATO has by passed me completely; that's both the original 1967 system and the current DTG system. "I know nothing" as they say. My one and only visit to Coburg was after the Vic line had gone but when the Northern was still complete there, and my one and only visit to Osborne was a high level high speed look around no more. And to cap that, the Vic. line is my least travelled tube line, not even once a year, if that, and when I do it's usually only becasue something else is disrupted. Oops digression again. |
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Tom
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Post by Tom on Sept 7, 2021 11:45:14 GMT
In the days of guards it was quite common for the doors to be opened just as the train came to a stop or slightly before. It is still possible with legacy CSDE equipment, provided the train is 'in the zone' and under a certain speed.
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Post by scheduler on Sept 8, 2021 18:06:16 GMT
Just because the line can theoretically achieve 32tph, does not mean it is wise to schedule it. Rolling stock available, probably insufficient for a start, and even if not, to put a timetable at absoloute maximum capacity is going to give you a 90% chance that on any given day by the end of the peak that the whole line is running late. It just does not make sense to do that. Every timetable should have some slack, somehow, for robustness.
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Post by superteacher on Sept 8, 2021 20:28:52 GMT
Just because the line can theoretically achieve 32tph, does not mean it is wise to schedule it. Rolling stock available, probably insufficient for a start, and even if not, to put a timetable at absoloute maximum capacity is going to give you a 90% chance that on any given day by the end of the peak that the whole line is running late. It just does not make sense to do that. Every timetable should have some slack, somehow, for robustness. But surely 32tph isn’t the maximum that can be achieved? And doesn’t the Vic line (with 36tph) operate at pretty much the theoretical capacity. I know it’s a much simpler line, but there’s pretty much no slack at all. |
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vincenture
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Post by vincenture on Sept 9, 2021 18:02:57 GMT
The Victoria line is built to have trains running at high speeds. I don't think the central section of the Northern line and the distance of those stations are helping with that...
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Post by superteacher on Sept 9, 2021 20:16:55 GMT
The Victoria line is built to have trains running at high speeds. I don't think the central section of the Northern line and the distance of those stations are helping with that... I think the real pinch point is Camden Town. Not sure that CBTC is thwt good at getting the best capacity out of the junctions. |
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North End
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Post by North End on Sept 9, 2021 21:02:51 GMT
The Victoria line is built to have trains running at high speeds. I don't think the central section of the Northern line and the distance of those stations are helping with that... I think the real pinch point is Camden Town. Not sure that CBTC is thwt good at getting the best capacity out of the junctions. Camden is always going to be an issue for as long as a mixed service operates. The moment two trains turn up along side each other wanting to go down the same branch, the headway has been killed, and this is going to occur frequently during a disruption scenario. This is why on the Northern it is vitally important to chase minor late running or out of turn working, as if left alone at some point they will cause a conflict somewhere. But even if crossing moves at Camden were completely axed I think the line would still struggle. It simply isn’t laid out as well as the Vic. |
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towerman
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Post by towerman on Sept 10, 2021 14:26:41 GMT
Why isn't Northern Line WWT58 & Jubilee Line WTT 17 on the TfL Timetables page yet?
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