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Post by jimbo on Mar 25, 2023 6:51:54 GMT
How the mighty are fallen! Worth a photo.
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Tom
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Post by Tom on Mar 25, 2023 15:24:21 GMT
Not really Bayswater had a slow approach when that went live. Now trains arrive at full speed and depart at full speed and teh testers are still in place. The tripcock testers at Bayswater have (or at least should have) had the ramps tied down and the gates turned around so that a tripcock can pass over at speed without the risk of being tripped. |
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Post by bazza55 on Mar 26, 2023 11:07:00 GMT
The 12mph speed restriction had nothing to do with the points. It was because of the presence of the tripcock tester in the platform area which became redundant this weekend, so the 12mph speed restriction should now be gone. EDIT: correction to what I originally posted.......the 12mph speed restriction will remain in place for now pending a future software drop. Why 12mph in ATO over this? I don't recall there being any restrictions over this when driven manually. |
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Tom
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Post by Tom on Mar 26, 2023 12:20:17 GMT
Your question has previously been answered here. The reason that it is still 12mph is because new software is required to remove the permanent speed restriction provided for the Tripcock Tester. Because SMA7 was so close behind SMA6 there wasn't sufficient time to produce and test a new version of software just for this one change - it will be caught up with other changes in a future build. |
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Post by programmes1 on Mar 26, 2023 12:31:18 GMT
How the mighty are fallen! Worth a photo. 1'll second that it would be good to see the lone operator. |
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Post by orienteer on Mar 26, 2023 16:26:32 GMT
Gone are the days of A Stock doing 70+ mph! For the A stock RIP  For speeds 70+ mph I have measured 67mph on S-stock northbound after Willesden Green, where the track is slightly downhill. It felt faster than I'd ever experienced judging by the sound of the motors, so I believe it was accurate! |
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Post by Dstock7080 on Mar 26, 2023 17:36:26 GMT
I have measured 67mph on S-stock northbound after Willesden Green, where the track is slightly downhill. It felt faster than I'd ever experienced judging by the sound of the motors, so I believe it was accurate! As said up-thread manual line speed on the MET is 60mph and S Stock have a maximum possible of 63mph. On the District prior to CBTC the line speed was 45mph and S Stock maximum was 47mph. The train sticks to this maximum like glue, there is no coasting. |
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Post by spsmiler on Mar 26, 2023 18:01:04 GMT
I have measured 67mph on S-stock northbound after Willesden Green, where the track is slightly downhill. It felt faster than I'd ever experienced judging by the sound of the motors, so I believe it was accurate! Certainly on roads downhill travel can cause speeds higher than are 'supposed' to occur, I would expect that it used to be the reality on railways too - in the days before computers ruled the roost. Today, in the era of black boxes and spies in the cab I would be surprised to see this be allowed (unless specially authorised). I do not know the situation at present but if this is not already the situation I bet that when this section of railway is converted to ATO the computers which control ('drive') the train will actually slow it down if it ever exceeds 60 mph. Of course train passengers want the highest standards of safety but (as is seen with the Elizabeth line) most of them also welcome faster journeys. Its a shame that travel speeds which were once acceptable and even expected are now seen in a negative light. |
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Colin
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Post by Colin on Mar 26, 2023 21:25:03 GMT
The train sticks to this maximum like glue, there is no coasting. I do not know the situation at present but if this is not already the situation I bet that when this section of railway is converted to ATO the computers which control ('drive') the train will actually slow it down if it ever exceeds 60 mph. To back up these points, a few days ago my train experienced a speed violation in ATO mode whilst going down the underpass approaching Barking westbound with the result being an emergency brake application applied by the CBTC system. Incidentally the CBTC system will also emergency brake the train if the speed limit is exceeded whilst driving manually in protected manual mode. So the CBTC system most definitely will not allow the train to exceed the speed limit on a given piece of the railway. |
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Post by spsmiler on Mar 26, 2023 22:37:26 GMT
]To back up these points, a few days ago my train experienced a speed violation in ATO mode whilst going down the underpass approaching Barking westbound with the result being an emergency brake application applied by the CBTC system. I hope that the emergency braking was only to reduce speed - and did not bring the train to a halt. I am most alarmed that a train would go in to full blown emergency brake mode (from full speed to stationary) just because it has exceeded a speed limit which has been declared as a notional limit for safety. Far better to make a gentle brake application to slow the train down. My reasoning is that emergency braking itself poses risks to the passengers - especially anyone who is standing / walking without a proper two handed grip on a handrail. A mangled mass of passengers with twisted limbs sliding on the floor - most likely uncontrollably - from one end of the train to the other end is not justified simply because a train was travelling faster than the speed limit. Broken limbs, and possibly worse; followed by an inquiry and quite probably (once the reason is known) legal action on behalf of the injured for punitive damages. A full blown emergency stop because of a real danger threat (eg: fallen tree in gale force winds) is a totally different story. I still remember the Northern line incident a few years ago and although it was an exceptionally rare event it happened and a train carrying passengers had to skip stations and travel at higher than usual speeds. Quite possibly present-day safety systems would have thwarted the safe and happy outcome. |
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Post by Dstock7080 on Mar 27, 2023 1:49:59 GMT
I hope that the emergency braking was only to reduce speed - and did not bring the train to a halt. The train will come to a stand and the ATO Start buttons will be required to be pushed. |
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Tom
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Post by Tom on Mar 27, 2023 10:08:27 GMT
I hope that the emergency braking was only to reduce speed - and did not bring the train to a halt. I am most alarmed that a train would go in to full blown emergency brake mode (from full speed to stationary) just because it has exceeded a speed limit which has been declared as a notional limit for safety. I do think that you are both trivialising adherence to the speed limits and massively exaggerating the risks from an emergency brake application. Speed limits are set for a reason - they are not arbitrary. While I tend to agree that an overspeed ought to be addressed via braking to the speed limit, the reasons for the system behaving in the way it does are many and varied and without a more full knowledge of the circumstances, it might be completely appropriate. What I would observe is that you are grossly overstating the risks in emergency braking - the rate is selected to give a controlled deceleration which, whilst sudden, does not give a jerk rate that is unacceptably high and cause injury. Your suggestion that this would cause "A mangled mass of passengers with twisted limbs sliding on the floor - most likely uncontrollably" is more reminiscent of how the press described the totally uncontrolled deceleration at Moorgate and in other collisions, rather than the controlled application of an emergency brake - and a such a description is, I feel, the sort a tabloid journalist would use looking for a sensational story, rather than someone who actually knows something about railways. Unannounced random emergency braking used to happen quite frequently on the Victoria line prior to resignalling, and whilst it was sudden, it never led to the circumstances you describe. Indeed, if you knew the signs and could grab a pole quickly, it was no worse than slightly heavy stop in a station. |
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Colin
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Post by Colin on Mar 27, 2023 17:10:34 GMT
I am most alarmed that a train would go in to full blown emergency brake mode (from full speed to stationary) just because it has exceeded a speed limit which has been declared as a notional limit for safety. [/snip] A mangled mass of passengers with twisted limbs sliding on the floor - most likely uncontrollably - from one end of the train to the other end is not justified simply because a train was travelling faster than the speed limit. Broken limbs, and possibly worse; Trains do not decelerate particularly quickly at all when emergency braking. They're not joking when they say a national rail train can take up to a mile to stop. Tom has covered it very well - as he said, when the emergency brake is applied on the train it applies at a surprisingly gentle rate. Chances are that if you've ever experienced a feeling that driver might have left it a bit late braking for a station and the train comes to a harsh stop, you've experienced the emergency brake having been applied. Ever been on a train that's come to a stop and then the driver announces a passenger alarm has been operated? That would have been an emergency stop. You may even have been on a train that's been tripped passing a red signal (though it does depend on what the driver reveals) - this would also have been an emergency stop as the train gets tripped. Granted we do tell passengers to hold tight if we carrying out passing a signal at danger as a procedure but that's only because we'll get tripped very soon after starting off from stationary so the stop will be that much harsher. Quite frankly though, its still not that hard a stop. I still remember the Northern line incident a few years ago and although it was an exceptionally rare event it happened and a train carrying passengers had to skip stations and travel at higher than usual speeds. Quite possibly present-day safety systems would have thwarted the safe and happy outcome. Quite the opposite actually. Service control can set up station skip and trains will travel through platforms at 18mph under TBTC/CBTC. Under legacy signalling (as was in place on the Northern line at the time of the incident you refer to) trains had to pass station starters at 5mph unless an overlap allowed for a higher speed. It should be noted that during the Northern line incident referred to the driver was never instructed to break any speed limits - just non stop stations. |
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Post by jimbo on Mar 28, 2023 1:55:35 GMT
The promise of CBTC on the sub-surface lines included more efficient working of flat junctions. The approach of trains would be controlled so that arrivals worked smoothly in parallel moves as if the junction did not exist. Is this working in practice? I suppose there is still insufficient approach to Earl's Court from the west, or Baker Street from the north. But do Praed Street and the Aldgate triangle work noticeably better with the new signalling?
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Post by Dstock7080 on Mar 28, 2023 5:38:28 GMT
(with apologies to the signal operators) I believe they do work better, less time for points to change after train departures, closer spacing of trains allows quicker junction operation, not so much holding at junctions - if no conflict, trains just keep running rather than waiting for manual intervention to operate points and clear signals, multiple tasks can be undertaken.
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Post by jimbo on Mar 28, 2023 7:03:55 GMT
The aim of CBTC is to keep trains a safe braking distance apart by automatically braking and accelerating to a target speed calculated to achieve this. ISTM if that system fails so that a train is over-speeding, what is the system to do but to promptly bring the train to a safe stand. Procedures can then be undertaken to maintain safe operation. |
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Post by bazza55 on Mar 29, 2023 19:19:37 GMT
I have measured 67mph on S-stock northbound after Willesden Green, where the track is slightly downhill. It felt faster than I'd ever experienced judging by the sound of the motors, so I believe it was accurate! As said up-thread manual line speed on the MET is 60mph and S Stock have a maximum possible of 63mph. On the District prior to CBTC the line speed was 45mph and S Stock maximum was 47mph. The train sticks to this maximum like glue, there is no coasting. Interesting that LU allows up to 2-3mph over the limit. Certain National Rail trains are now having limiters fitted even slightly below the speed limit for the unit, even though everything has to be overspeed tested at 10%. I assume 10% applies to LU too? |
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Post by jimbo on Mar 29, 2023 19:31:47 GMT
I think speed limiting was introduced with the new Victoria Line, so a long while back now. Driving in slow manual was allowed up to 10mph, which was considered a safe speed. However, with no margin before emergency brake application, in practice drivers could only run up to 8mph which caused excessive delays. Future stocks specified up to 15mph, which allowed confident operation up to 12mph, an effective 50% increase. Happy to be corrected after so long!
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Tom
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Post by Tom on Mar 29, 2023 22:11:17 GMT
On modern stocks it’s 16km/h which is around 10mph.
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Post by t697 on Mar 30, 2023 5:34:07 GMT
Future stocks specified up to 15mph, which allowed confident operation up to 12mph, an effective 50% increase. Happy to be corrected after so long! I seem to recall this was only on D78 stock, maybe 83TS as well. Soon after, there was a further review about what speed would best support a driver in 'being able to stop short of any obstruction' in adverse conditions and as a result the setting was reverted to 10mph or 17km/h. In even later stocks the 10mph is rounded down to 16km/h. S stock and I think 09TS have a feature automatically regulating the speed to just below the 10mph safety brake speed under overall driver control and vigilance. So they can maintain about 8.5 - 9mph in RM. |
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Post by capitalomnibus on Mar 31, 2023 22:35:34 GMT
As an aside, the platform (and ticket hall) indicators at Upminster now work better, with time countdown and first platform departure, with countdown of that departure on all screens. Generally all describers in CBTC much better! I am sure when I was in Upminster in November last year the destination boards were working as you have shown. |
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DWS
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Post by DWS on Apr 1, 2023 5:56:41 GMT
Today 1 April 2023 the District Line is suspended between Earls Court and Olympia due to a signal failure , whats the problem as I recall it’s happening for the last couple of weekends ?
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Post by Dstock7080 on Apr 1, 2023 6:16:50 GMT
No.32b points at Earl’s Court failed overnight 18 March and were secured so that trains from pfm.4 must run towards Wimbledon.
A replacement was undertaken but something is delaying their recommissioning, so unfortunately the weekend Olympia service has been unable to operate during the Ideal Home Show.
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Post by Dstock7080 on Apr 1, 2023 6:24:24 GMT
I am sure when I was in Upminster in November last year the destination boards were working as you have shown. They didn’t indicate how many minutes before departure of the train on this platform or the others, just presumed destination.  |
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Post by philthetube on Apr 3, 2023 16:22:32 GMT
I have measured 67mph on S-stock northbound after Willesden Green, where the track is slightly downhill. It felt faster than I'd ever experienced judging by the sound of the motors, so I believe it was accurate! As said up-thread manual line speed on the MET is 60mph and S Stock have a maximum possible of 63mph. On the District prior to CBTC the line speed was 45mph and S Stock maximum was 47mph. The train sticks to this maximum like glue, there is no coasting. Unless things have changed in the 2 years since I retired this is not correct, it was easily possible to achieve 70+ through Chalfont SB on the Met, at which point the speedo reset, I have known drivers claim 90+ and to have checked this using a phone, I have know idea if this is true but it is believable. |
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Post by spsmiler on Apr 3, 2023 20:33:46 GMT
I wonder if what Dstock7080 said only applies to when travelling in CBTC mode - not when in 'human driven' mode? I also wonder whether these trains have 'spy in the cab' monitoring systems so that a train's speed is recorded at all times - and staff who travel at higher than permitted speeds are disciplined? Personally speaking I still regret the lower top speed than the A stock and indeed feel that the 60ish mph limit is very much a retrograde step. Forward progress suggests that the top speed should be at least 70 mph - if not 80 mph. If I recall correctly the Chilterns can travel at 90 mph and very likely would have been able to travel at such speeds on LT metals had they existed earlier, but alas LT reduced track speed limits. When one looks at the Elizabeth line's success a part of it is the much faster travel and hence reduced journey times through Central London. Its a shame that the same cannot be said about the Met's service to its outer reaches. |
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Post by silenthunter on Apr 3, 2023 21:09:31 GMT
Are the signal failures we still getting on non-CBTC bits?
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Post by philthetube on Apr 4, 2023 0:47:43 GMT
S Stock does have a "Black box" so speeds are recorded, I have never known a driver be disciplined over excess speed at the north end of the line but people have been spoken to for exceeding lower speed limits.
2 years since I retired so things may have changed.
70 mph north of Harrow would be beneficial, I don't think there is any point in going faster, North of Ricky northbound S stock could probably be opened up to run faster but Chiltern are slower than S stock now.
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Post by alpinejohn on Apr 4, 2023 7:28:24 GMT
... 70 mph north of Harrow would be beneficial, I don't think there is any point in going faster, North of Ricky northbound S stock could probably be opened up to run faster but Chiltern are slower than S stock now. I am not sure about Class 165's being slower... When new basic Class 165 (Chiltern Turbo) units were designed for a 75MPH (120kph) top speed likewise the maximum designed speed for the Bombardier S8 is 62MPH(100kph). I realise that the Turbos will not accelerate quite as fast as the S8 stock especially in poor rail adhesion conditions and that like many older vehicles the Class 165's may now struggle to reliably achieve that top speed now. Inevitably that makes timetabling decisions and programming line speeds for the S8 stock an interesting challenge on the shared route. To optimise traffic flow on a Network Rail/LUL shared route it seems likely that someone will have developed accelleration and braking profiles to work out just how close different rolling stock could operate on the shared route whilst avoiding wasteful bunching and excessive braking. This optimisation may explain why it makes sense to keep the S8 target speed at 100kph lower than the top speed on the same route allowed for the Chiltern Turbos. |
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Post by bazza55 on Apr 4, 2023 20:11:52 GMT
Once S8 stock is running under CBTC and able to accelerate quicker to its 100kph top speed, it will most likely set quicker run times between stations than Chiltern stock. Going Northbound the issue for all trains are the steep gradients. Southbound ghe gradients set a different challenge from a braking point of view. Until the shared section requires a frequency of less than 5 minutes, the slight performance differential between Chiltern and S Stock should not be an issue.
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