Ben
fotopic... whats that?
Posts: 4,282
|
Post by Ben on May 12, 2019 14:48:01 GMT
CBTC testing in SMA3 this weekend is seeing trains using platform 2 at Tower Hill from both directions and movements. Also Farringdon-King’s Cross, which under conventional tripcock signalling is maximum 40mph, running at 52mph under CBTC. I do believe reading on here though that the northern circle, when last resignalled, was done with 40tph throughput in mind. I suppose the question is which is more useful or practical for a central london stretch, lower speed but higher frequency, or higher speed but lower frequency.
|
|
|
Post by londonstuff on May 12, 2019 15:01:54 GMT
CBTC testing in SMA3 this weekend is seeing trains using platform 2 at Tower Hill from both directions and movements. Also Farringdon-King’s Cross, which under conventional tripcock signalling is maximum 40mph, running at 52mph under CBTC. I do believe reading on here though that the northern circle, when last resignalled, was done with 40tph throughput in mind. I suppose the question is which is more useful or practical for a central london stretch, lower speed but higher frequency, or higher speed but lower frequency. I’m not an expert at this. Is it as simple as that? Surely lower speed, although it means smaller gaps between trains means longer trips over flat junctions. Although not practical on LU most foreign services seem to favour longer gaps between trains but have super long and wide trains to scoop everyone up, presumably like Crossrail will be. I’m happy to be corrected and there’s probably 1001 other factors.
|
|
|
Post by Dstock7080 on May 12, 2019 15:23:20 GMT
|
|
|
Post by t697 on May 12, 2019 17:55:08 GMT
CBTC testing in SMA3 this weekend is seeing trains using platform 2 at Tower Hill from both directions and movements. Also Farringdon-King’s Cross, which under conventional tripcock signalling is maximum 40mph, running at 52mph under CBTC. I do believe reading on here though that the northern circle, when last resignalled, was done with 40tph throughput in mind. I suppose the question is which is more useful or practical for a central london stretch, lower speed but higher frequency, or higher speed but lower frequency. Anyone have evidence to support 40tph on the previous North Circle signalling? Sound unlikely to me. Primarily because of the flat junctions, even allowing for shorter trains like C stock and back in the 50's 5 car O/P stock. I've not heard of better than nominal 90 second headways on legacy signalling anywhere on LUL and although that equates to 40tph, you need some recovery margin to operate a practical and reliable service. Years ago there was a rule of thumb about 90 second headways to operate a 2 minute service frequency.
|
|
|
Post by spsmiler on May 12, 2019 18:42:30 GMT
CBTC testing in SMA3 this weekend is seeing trains using platform 2 at Tower Hill from both directions and movements. Also Farringdon-King’s Cross, which under conventional tripcock signalling is maximum 40mph, running at 52mph under CBTC. When I was a schoolboy in the 1970's and sometimes got into the cab of trains which commenced their journeys in the (now sadly closed) bay platform at Liverpool Street station, A stock trains travelling from Farringdon to Kings Cross were usually travelling at more than 40mph by the time they reached the original Metropolitan railway Kings Cross station. However, returning to the present era, I am pleased to see that the highest permitted speed will be rising by about 25%. I suppose the question is which is more useful or practical for a central london stretch, lower speed but higher frequency, or higher speed but lower frequency. I think it depends on the time of day / service frequency being operated. At quieter times passengers will appreciate the extra speed. But at the height of the rush hour passengers will prefer to be constantly moving - rather than travelling at full speed and then spending time stopped outside the station (waiting for the platform to clear) at the equivalent of a red signal. What might be worthwhile are passenger information messages which say: " this train is close to the train in front and therefore to avoid stopping at a red signal is travelling slowly." Please note that I avoided the word 'congestion'. Thats road traffic terminology! Maybe what should also be considered here is the ability of the next station to handle the number of passengers using the platform and passageways. Simon
|
|
Ben
fotopic... whats that?
Posts: 4,282
|
Post by Ben on May 12, 2019 18:53:47 GMT
I do believe reading on here though that the northern circle, when last resignalled, was done with 40tph throughput in mind. I suppose the question is which is more useful or practical for a central london stretch, lower speed but higher frequency, or higher speed but lower frequency. Anyone have evidence to support 40tph on the previous North Circle signalling? Sound unlikely to me. Primarily because of the flat junctions, even allowing for shorter trains like C stock and back in the 50's 5 car O/P stock. I've not heard of better than nominal 90 second headways on legacy signalling anywhere on LUL and although that equates to 40tph, you need some recovery margin to operate a practical and reliable service. Years ago there was a rule of thumb about 90 second headways to operate a 2 minute service frequency. Whoops! It would appear I'm misremembering a comment possibly from Tom in this thread in 2012 districtdavesforum.co.uk/thread/19141
|
|
|
Post by goldenarrow on May 12, 2019 19:15:24 GMT
I do believe reading on here though that the northern circle, when last resignalled, was done with 40tph throughput in mind. I suppose the question is which is more useful or practical for a central london stretch, lower speed but higher frequency, or higher speed but lower frequency. Anyone have evidence to support 40tph on the previous North Circle signalling? Sound unlikely to me. Primarily because of the flat junctions, even allowing for shorter trains like C stock and back in the 50's 5 car O/P stock. I've not heard of better than nominal 90 second headways on legacy signalling anywhere on LUL and although that equates to 40tph, you need some recovery margin to operate a practical and reliable service. Years ago there was a rule of thumb about 90 second headways to operate a 2 minute service frequency. I remember what some LTM friends who were ex-LT signallers from Aldgate (later A stock train operators) said when the stats were coming out for the current incarnation of the SSR Resignalling were released. 30 tph was said to be just within reach of the capabilities of the signaling system in the 60's. Certainly what I do know is that the ergonomics and separation of controls that were last used on the A stock (separate controls for motoring and braking) were much more favourable for approach control signals compared to the combined traction brake controllers we get on more recent stock. Just to give an example of how close you used to be able to get with dead mans handled stock, have a look at how close this A stock gets to signal OE 260 on the Westbound at Moorgate. I know from a personal perspective of there the driving position is that an S stock wouldn't get anywhere as near.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on May 12, 2019 19:54:58 GMT
Anyone have evidence to support 40tph on the previous North Circle signalling? Sound unlikely to me. Primarily because of the flat junctions, even allowing for shorter trains like C stock and back in the 50's 5 car O/P stock. I've not heard of better than nominal 90 second headways on legacy signalling anywhere on LUL and although that equates to 40tph, you need some recovery margin to operate a practical and reliable service. Years ago there was a rule of thumb about 90 second headways to operate a 2 minute service frequency. I remember what some LTM friends who were ex-LT signallers from Aldgate (later A stock train operators) said when the stats were coming out for the current incarnation of the SSR Resignalling were released. 30 tph was said to be just within reach of the capabilities of the signaling system in the 60's. Certainly what I do know is that the style of controls that were last used on the A stock (separate controls for motoring and braking) were much more favourable for approach control signals compared to the combined traction brake controllers we get on more recent stock. Just to give an example of how close you used to be able to get with dead mans handled stock, have a look at how close this A stock gets to signal OE 260 on the Westbound at Moorgate. I know from a personal perspective that an S stock wouldn't get anywhere as near. That driver knows how to drive their train well, but can all drivers on the line drive at that standard all the time? The whole system is being designed so that you can get standardised results across the network, as you are taking the human factor out of it partly. I bet if all drivers drove to this standard, you could actually end meeting or even exceeding a better TPH than the automated system.
|
|
|
Post by t697 on May 12, 2019 21:35:19 GMT
It's not about the driveability of S stock using the Traction/Brake Controller. That gives very good fine control at least as good and maybe better than the A stock. The driver of that train in the video was very probably standing up to view the signal down in the six-foot. Viewing angles seated in an S stock are nowhere near as good and that's one reason why most drivers wouldn't run so close up to the signal before it cleared. Also if that signal had not cleared as the driver probably anticipated by viewing where the train ahead had got to, they would have got tripped. Skilled judgment, but not quite as trained!
|
|
Chris M
Global Moderator
Forum Quizmaster
Always happy to receive quiz ideas and pictures by email or PM
Posts: 19,359
|
Post by Chris M on May 12, 2019 21:39:25 GMT
As I understand it, the consequences of passing a signal at danger are (potentially) more severe now than in previous eras, and the philosophy/culture of defensive driving is somewhat more significant these days. These will undoubtedly play a role in different driver behaviours.
|
|
|
Post by goldenarrow on May 12, 2019 22:00:13 GMT
@luacton , Indeed, you probably could get an S stock right up to a signal like for like, my main concern would be that it just wouldn't be very comfortable. The Moscow metro gets ATO levels of service or even better because of human skill not a VOBC. I also agree that if the signalling system were redesigned for the performance of the S stock taking into account its performance levels aswell as driving controls, you would end up with a service frequency that could surpass ATO. t697 , With one caveat, that jolt you get when the brake blocks kick in, it sometimes is the case that drivers crawl for much longer especially at draw up locations to avoid excessive jolting which is really noticable when standing/walking. Chris M , Still, to me, the fact that signalling layouts that in some cases were in already place when air raid sirens where blaring over London are still going be keeping parts of the Underground moving till 2022/23 is still quite incredible even if they do not necessarily squeeze as much space out as possible.
|
|
class411
Operations: Normal
Posts: 2,718
|
Post by class411 on May 13, 2019 8:06:36 GMT
... it sometimes is the case that drivers crawl for much longer especially at draw up locations to avoid excessive jolting which is really noticable when standing/walking. I'm so glad you mentioned that. I'd always thought it was just something some drivers did to 'ring the changes' and alleviate boredom.
|
|
|
Post by PiccNT on May 13, 2019 9:41:48 GMT
As I understand it, the consequences of passing a signal at danger are (potentially) more severe now than in previous eras, and the philosophy/culture of defensive driving is somewhat more significant these days. These will undoubtedly play a role in different driver behaviours. You are probably correct. From anecdotal evidence, it seems "back in the day" SPaD's at automatic signals were often not reported and it seems from mess room chat, actively discouraged. Nowadays, SPaD's are taken very seriously and if you have four safety critical incidents in a 2 year period, you could find yourself in a bit of bother. Coming back to the video, it seems signal OE260 is the draw up signal for what I will presume is OE26, the station starter and is designed to protect overruns at that signal and the diverging junction ahead. The draw up signal will work automatically based on a timing section so skilled drivers will understand the approach speed required to clear the signal. However, the "Can I stop if I need to" rule seems not to be in practice in this instance! We do teach defensive driving but in my view, the training, certainly on my manual line, is insufficient for the trainee (or cross transfer) to fully appreciate the ins and outs of the signalling on the line. You really do need an understanding of what is likely to happen in any given circumstance at pretty much every section of the line. Most drivers do not have this understanding and that's probably one reason why we have issues with the number of SPaD's seen. From my observations, the standard of driving and line knowledge ranges from actually very good to absolutely abysmal! I expect a rocket for going off topic.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on May 13, 2019 10:18:53 GMT
From a signalling point of view we saw the SPAD’s rocket up around the period of PPP was started. Yes we used to try and cover up the driver before PPP I.e football, rubbish etc etc but since circa 2001 we was told to stop this practice
80% roughly of SPAD’s these days are classed as Technical SPAD’s where a piece of the signalling equipment has failed causing the signal to go back to danger. But that leaves the other 20% which is usually driver error where they expect the signal to clear or the signaller has put the signal back in front of the driver.
The trains do themselves have little black box style data loggers but it’s not that accurate to say 100% if the driver has made the error and at what speed the driver was travelling at to say conclusively that it was the drivers fault.
That signal at Moorgate is to protect the junction ahead like most draw ups the train is speed checked if the starter it’s protecting is at danger. If the starter was clear then that draw up would show a green as no speed check is necessary. Also if the previous move was not out or in of the bay road at Moorgate the draw up would show a yellow again no speed check necessary.
|
|
|
Post by londonstuff on May 13, 2019 13:16:42 GMT
As I understand it, the consequences of passing a signal at danger are (potentially) more severe now than in previous eras, and the philosophy/culture of defensive driving is somewhat more significant these days. These will undoubtedly play a role in different driver behaviours. You are probably correct. From anecdotal evidence, it seems "back in the day" SPaD's at automatic signals were often not reported and it seems from mess room chat, actively discouraged. Nowadays, SPaD's are taken very seriously and if you have four safety critical incidents in a 2 year period, you could find yourself in a bit of bother. Coming back to the video, it seems signal OE260 is the draw up signal for what I will presume is OE26, the station starter and is designed to protect overruns at that signal and the diverging junction ahead. The draw up signal will work automatically based on a timing section so skilled drivers will understand the approach speed required to clear the signal. However, the "Can I stop if I need to" rule seems not to be in practice in this instance! We do teach defensive driving but in my view, the training, certainly on my manual line, is insufficient for the trainee (or cross transfer) to fully appreciate the ins and outs of the signalling on the line. You really do need an understanding of what is likely to happen in any given circumstance at pretty much every section of the line. Most drivers do not have this understanding and that's probably one reason why we have issues with the number of SPaD's seen. From my observations, the standard of driving and line knowledge ranges from actually very good to absolutely abysmal! I expect a rocket for going off topic. This is fascinating so I won’t send you to the Tower via Traitors’ Gate just yet but subsequent posters, feel free to get back on topic.
|
|
|
Post by commuter on May 25, 2019 16:02:17 GMT
Does anyone know, why on the ATO section the trains only seem to be using friction brakes? It’s noticeably quieter than on the rest of the line but I’m sure blended braking is more efficient.
|
|
|
Post by goldenarrow on May 25, 2019 16:54:06 GMT
Does anyone know, why on the ATO section the trains only seem to be using friction brakes? It’s noticeably quieter than on the rest of the line but I’m sure blended braking is more efficient. I believe somewhere above, either Tom or br7mt mentioned that FOBA's (Friction Brake Only Applications) which can be scheduled, need to be used every once in a while to maintain their expected performance based on rolling stock performance after the Northern and Jubilee lines turned over to ATO. There is video evidence of trains in ATO stopping at Goldhawk Road WB with the typical use brake blending that as you say, is much more efficient in terms of relative power consumption. I'm sure as the more migration zones are commissioned we will see brake blending in ATO in time.
|
|
class411
Operations: Normal
Posts: 2,718
|
Post by class411 on May 25, 2019 18:50:34 GMT
I'm not sure if this has anything to do with the above posts, but when I was moving up trhe stairs at Shepherd's Bush Market eastbound, a train was approaching westbound making the strangest noise.
It sounded somewhat akin to the sound of an S-Stock starting off, but it was extremely loud and the pitch remained the same until it stopped. Unfortunately, an eastbound train arrived so I could not hear what sort of a sound it made on departure.
Had the velocity of the train in question been constant, I'd have said it sounded like the motors running against friction brakes, but as the train was slowing to a stop, it could not have been that. (I'm assuming that the wheels wee not all locked and it was not sliding in!)
|
|
rincew1nd
Administrator
Junior Under-wizzard of quiz
Posts: 10,222
|
Post by rincew1nd on May 25, 2019 21:42:42 GMT
IIRC the S Stock named "Tim O'Toole" has different motors to the rest of the fleet which can be identified easily as they sound different.
|
|
a60
I will make the 8100 Class DART my new A Stock.
Posts: 743
|
Post by a60 on May 26, 2019 10:10:40 GMT
IIRC the S Stock named "Tim O'Toole" has different motors to the rest of the fleet which can be identified easily as they sound different. I’m on it right now and the best way I can describe it is that it sounds like it has been fitted with a turbocharger.
|
|
|
Post by spsmiler on Jun 13, 2019 17:20:39 GMT
I see that a significant portion of the District line is closed this coming weekend, will that be for CBTC testing? if so, might this explain why the four track route has replacement buses rather than Piccadilly line trains using District line tracks? Moving further afield, re: interoperable areas on the Met Main Line, would I be right in assuming that only the mainline north of Harrow-OT-Hill will be interoperable (since Chiltern trains can not access the local line?) One other question, maybe though the answer is 'why bother asking' or 'we will address that issue if / when it is built' but anyway, here goes. On the off-chance that the Croxley link does actually somehow become funded, will it (and the North Curve) also be signalled as an interoperable line? After all, it was mooted that Chiltern would possibly be interested in an Aylesbury - Watford Junction service!
An an aside, Chiltern's franchise will be up for renewal in 2021. I wonder if electrification will be on the cards? Restoration of higher line speeds, indeed, raising even higher than before - possibly to 90mph? 100mph? (Obviously not at Rickmansworth station) A desire for LU to fit AWS / ATP equipment so that Tripcocks wont't be needed? I am also aware of developments further north of Aylesbury that might affect the Chiltern service that travels along the joint line (East West rail reopening, more...)
Thanks Simon
|
|
|
Post by MoreToJack on Jun 13, 2019 18:29:22 GMT
I see that a significant portion of the District line is closed this coming weekend, will that be for CBTC testing? if so, might this explain why the four track route has replacement buses rather than Piccadilly line trains using District line tracks? Correct - 4LM Signalling testing throughout the SMA 5 area (Earl's Court to Barons Court), including associated buffer sections. This would preclude use of the local lines. Moving further afield, re: interoperable areas on the Met Main Line, would I be right in assuming that only the mainline north of Harrow-OT-Hill will be interoperable (since Chiltern trains can not access the local line?) Correct, Main Line only. One other question, maybe though the answer is ' why bother asking' or ' we will address that issue if / when it is built' but anyway, here goes. On the off-chance that the Croxley link does actually somehow become funded, will it (and the North Curve) also be signalled as an interoperable line? After all, it was mooted that Chiltern would possibly be interested in an Aylesbury - Watford Junction service! Part of the reason for ditching Watford Junction was that there was no funding for ATO signalling along the link. It was specified and to be built and equipped with conventional (tripcock) signalling only, although I don't believe any detailed work was done for this.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jun 13, 2019 18:42:11 GMT
Assets were purchased for the Watford extension and was kept in a secret store somewhere near
Of course I am not going to disclose the facility
|
|
|
Post by spsmiler on Jun 14, 2019 1:16:36 GMT
Thanks for the replies, of course I am not going to ask whose garage (smile) has been co-opted for storage of the signalling equipment, its good enough just to know that this have been thought of - and far better than trying to obtain the signalling equipment in (for instance) 5 years from now and being laughed at for wanting components using technology so ancient that its now in a museum!
|
|
Tom
Administrator
Signalfel?
Posts: 4,083
|
Post by Tom on Jun 14, 2019 12:57:11 GMT
An an aside, Chiltern's franchise will be up for renewal in 2021. I wonder if electrification will be on the cards? Restoration of higher line speeds, indeed, raising even higher than before - possibly to 90mph? 100mph? (Obviously not at Rickmansworth station) A desire for LU to fit AWS / ATP equipment so that Tripcocks wont't be needed? I am also aware of developments further north of Aylesbury that might affect the Chiltern service that travels along the joint line (East West rail reopening, more...) Negative on all counts, other than a possible line speed increase back to 70mph.
|
|
|
Post by spsmiler on Jun 16, 2019 0:48:44 GMT
An an aside, Chiltern's franchise will be up for renewal in 2021. I wonder if electrification will be on the cards? Restoration of higher line speeds, indeed, raising even higher than before - possibly to 90mph? 100mph? (Obviously not at Rickmansworth station) A desire for LU to fit AWS / ATP equipment so that Tripcocks wont't be needed? I am also aware of developments further north of Aylesbury that might affect the Chiltern service that travels along the joint line (East West rail reopening, more...) Negative on all counts, other than a possible line speed increase back to 70mph. Even 70mph would be 'something'!
|
|
metman
Global Moderator
5056 05/12/1961-23/04/2012 RIP
Posts: 7,394
|
Post by metman on Jun 16, 2019 11:48:14 GMT
S stock are limited to 62mph although I wonder if that could be increased? I’m not sure that I would want to travel at 70mph on those little wheels!
|
|
|
Post by spsmiler on Jun 16, 2019 12:46:40 GMT
S stock are limited to 62mph although I wonder if that could be increased? I’m not sure that I would want to travel at 70mph on those little wheels! These trains are really meant for short distance urban journeys where acceleration is of greater importance than top speed. Especially the Metropolitan Main Line fast services would benefit more from trains designed for higher top speeds, as greater acceleration is of lesser importance on journeys where the inter-station journey times can be 5 minutes and even more. The Chiltern diesels can do at least 90 mph, possibly even 100 mph - this being the upper speed in the route to Birmingham which was recently revamped and brought closer to present-day speed expectations for main lines that are not High Speed lines. You only have to look at the situation on the roads (numbers of people caught 'speeding') to know that people do value faster travel and its only those who take decisions (or ride pedal bikes) who favour slowness. The railways of course are the safest way to obtain the desired higher speeds. To make the topic of travelling speed directly relevant to SSR resignalling, I recall a mention a while ago about how automation will see a significant rise in the the speed limit between Farringdon and Kings Cross to 52 mph, reducing the journey time quite noticeably.
|
|
|
Post by goldenarrow on Jun 16, 2019 14:07:50 GMT
I don’t think that Metropolitan line trains would exceed their current top line speeds given that SelTrac S40 itself is limited to 108kmh / 67mph. The Dubai metro uses a similar variant of S40 to what is being installed on the SSR and it tops out at 62mph even though the rolling stock is capable of much more. spsmiler , I hope the run from Kings X to Farringdon isn’t lifted any further given that it would mean a sharp brake for the curves over the Widened Lines East and likewise past the disused MET platforms East. Even at 40mph which is the current speed, you will rarely get a train maxing out during the peak periods, a 50mph+ would surely start to eat away at capacity.
|
|
|
Post by norbitonflyer on Jun 16, 2019 15:14:58 GMT
only those who take decisions (or ride pedal bikes) who favour slowness. I think it's the local inhabitants bringing pressure to bear on the decision makers in the area - although when those inhabitants get in their cars they are often caught by the speed cameras they themselves campaigned for. Observation of cyclists' behaviour suggest many of them are very much in favour of speed.
|
|