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Post by 35b on Feb 13, 2023 8:39:16 GMT
Fair comments about specialism, but they make my point. Even respecting the constraints of safety critical work, what’s been described is an architecture that is inflexible and requires very material spend to make change. The inability to cope with splitting or difficulty in implementing new types are not reasons for change, but symptoms of a design weakness that will, over time, impose disproportionate cost.
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Post by t697 on Feb 13, 2023 12:21:22 GMT
btw, can the signalling system cope with the rescue of a failed train (eg: power collection shoes damaged, need replacing) by attaching another train to it - without shutting down services on the whole of the SSR? S stock assisting S stock needs Restricted Manual to be used. It does in the Tripcock area too because the assisting (pushing) train needs to cut out the tripcock otherwise it will get tripped since the trainstop will be up by the time its front car gets to it. A safety feature is that the trip can only be cut out in RM. So it shouldn't be that much worse in the ATC area in principle. |
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Post by joshua on Feb 23, 2023 21:37:02 GMT
btw, can the signalling system cope with the rescue of a failed train (eg: power collection shoes damaged, need replacing) by attaching another train to it - without shutting down services on the whole of the SSR? I don't disagree they have not allowed for this type of non standard move. You can not go into every last possible if and but and maybe to do everything you can do on your Hornby train set. First, rescuing by attaching one train (S stock) to another train (of S stock) is allowed for - it ain't easy, but it is allowed for. So you can eliminate that one from your objection. What happens if a Chiltern Train fails and is trapped by S Stock at each end? How does the signalling system know what length of trains Chiltern would be running? Quotes amended - can we please try to avoid quoting complete posts and keep quotes short and to the point? - Tom |
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Post by d7666 on Feb 24, 2023 15:57:16 GMT
What happens if a Chiltern Train fails and is trapped by S Stock at each end? How does the signalling system know what length of trains Chiltern would be running? Down at that level of detail I do not know the specific answer. The whole set-up with Chilterns over LU infrastructure, both current clockwork signalling and with future CBTC, is riddled with exceptions to prove rules consisting of bespoke solutions that can not be taken as applying elsewhere. For example, even today, that 16x Chilterns units have tripcocks and while running in the Met have no AWS or TPWS or ATP is a bespoke solution. Spookily, I was chatting over a few ales yesterday evening similar subject with a Chilterns driver. It is true there are other examples of main line trainstops and tripcocks, and main line non AWS and main line non TPWS, but all are equally unique to their bespoke application and the trainspotter view of "... but at Fludgwick Junction class 123 does this... " does not mean that applies anywhere else. Mersey 507/508 have tripcocks, but that don't allow them on the Met even if they could take power. Neither does that allow S-stock on the Mersey lines even if they fitted and could take power. And so on. Back to CBTC I aSK Axle counters ? Tom ? |
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Tom
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Post by Tom on Feb 24, 2023 21:23:28 GMT
The simple answer is: It doesn't.
TBTC and CBTC uses axle counters for tracking non-communicating trains (as well as a few other purposes) and this is no exception. Chiltern trains cannot be as accurately positioned as a communicating train, and as such we need more (and smaller) axle counter sections than we do in the CBTC core area to provide sufficient glanularity and still maintain the headway.
If a Chiltern train is stationary, a communicating CBTC train will be held a safety distance away from the axle counter block in which the Chiltern train is sitting. This is probably closer than two Chiltern trains can get to each other, but not as close as two CBTC trains can.
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Post by david123 on Feb 25, 2023 8:16:59 GMT
So the District Line is only Upminster to South Ken this week, and a couple of sections out west, yet there is no DMI info online etc as per usual every time a line is part shut for engineering works, let the platform DMIs work and announce the trains fine.
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Post by gigabit on Feb 25, 2023 11:56:32 GMT
What are they doing this weekend on the District Line?
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Post by Dstock7080 on Feb 25, 2023 11:59:46 GMT
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Post by david123 on Feb 25, 2023 20:03:38 GMT
Err yeah, I know that, my question is why are the online DMI data online not showing the trains to South Kensington, yet the platforms are... So TFL as per usual switch off the online live feeds for some reason.
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Post by david123 on Feb 25, 2023 20:08:44 GMT
tfl.gov.uk/tube/stop/940GZZLUWSM/westminster-underground-station?lineId=circle,district We are unable to show live updates at the moment. Please use Timetables to check the frequency of your service. As per usual when part of the line has a weekend shunt down, really don'y know why they do that, just stupid, meals no real time online DMI info for tfl site or any other external site such as UK Departure boards etc
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Post by bazza55 on Mar 1, 2023 11:59:19 GMT
I don't think I'll ever understand this fascination with speed. You won't see 62mph anywhere at the moment as there's currently a 56mph cap in place whilst a recently identified issue is resolved. In any case I would have thought it's relatively obvious that you'll only see such a high speed on a relatively straightforward piece of track, timetable and sufficient gaps between trains permitting, where there's a decent run between stations. Sorry but I think a full reply will take me too far off topic, but I hope this is acceptable - ever since railways began the trend has been for faster travel as reduced journey durations are generally seen as positive attributes that attract more passengers. Took a brief trip West Ham eastbound to Upminster and back. Wow - what a difference in performance between CBTC and legacy signalled sections. Now the S7's achieve 50mph in 35 seconds. On a clear run (not too close to preceding trains) the speed difference is startling. I never thought the S7's had that level of acceleration in them. As soon as we can start seeing some 100kph running, we will see whether these are the fastest 3rd/4th rail emus to 60mph. Yes, the average passenger is verly likely to notice the difference in speed and the journey time will feel faster as a result. For once the District line does not 'feel' like a slow railway. Have not analysed any data to work out reductions in station to station times. I'm sure they are not as dramatic as they feel. But the potential is there. Rounding the curve at East Ham (seems to be a LOT SMOOTHER NOW) at close to 50mph and then accelerating towards Barking under the flyovers was dramatic - never experienced that level of speed there before. I would imagine that even some of the drivers have had white knuckles the first few times they let the computer drive at those much higher speeds. It is a shame that lots of the pointwork seems to be in a very ppor state causing speed restrictions over them. Plus the breaks in the conductor rail in those areas do cause some jerky acceleration due to problems with power delivery. Moving back on to the legacy section beyond Becontree confirms the difference in acceleration. It is noticeably more pedestrian. The extension of CBTC to Barking can not come quick enough. I wonder what the optimal headway is along the open air section of route with differing distances between stations and speed limits. It does seem running closer than 3 min apart causes additional slowings. |
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Colin
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Post by Colin on Mar 1, 2023 17:08:49 GMT
Yes, the average passenger is verly likely to notice the difference in speed and the journey time will feel faster as a result. For once the District line does not 'feel' like a slow railway. Have not analysed any data to work out reductions in station to station times. I'm sure they are not as dramatic as they feel. But the potential is there. Overall journey times across several stations won't have changed though, simply because the timetable hasn't changed. Trains may well be achieving a faster top speed between some stations, but they also start to brake earlier than we did when driving manually. That being said, I'll grant you there are some gains to be had on the longer runs between stations but all that serves to achieve without the timetable change is longer dwell times in platforms. East Ham westbound is often 35 seconds plus for example. |
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Post by bazza55 on Mar 1, 2023 21:32:32 GMT
Yes. I completely forgot to mention that I noted dwell times are longer, especially at Becontree switching from legacy signalling to CBTC.
And yes the CBTC driven trains brake more gently - seeming to hit the platform ramp at appx 28mph compared to 30mph+ when 'driven' by real drivers.
The braking scenario is interesting as Victoria and Central line drivers i know claim they cannot easily match or beat the computer driven braking rate, But in this case the opposite seems to be true.
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Post by t697 on Mar 2, 2023 17:52:44 GMT
On the Victoria line the station approaches are all in tunnels so the ATO brake rate can be and indeed is, higher than would be appropriate for open section running. Same for Central line tunnel sections at least.
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Post by principlesdesigner on Mar 2, 2023 23:24:21 GMT
The braking scenario is interesting as Victoria and Central line drivers i know claim they cannot easily match or beat the computer driven braking rate, But in this case the opposite seems to be true. The guy who was involved with the design of the Westinghouse ATP/ATO system for the Central line was obsessed with minimising jerk rate (cyclical acceleration and braking), whilst minimising platform reoccupation times, hence, the Central line system and its later Victoria line offspring aim to get to the target speed, (which is marginally less than the maximum, hence removing the accelerate / brake &c at the higher end ) as quickly as possible and then one service brake into the platform, dependant upon the position of the train in front. I was out with a test train crew in the early 90's doing ATP /ATO testing, and coming into Wanstead, the driver punched the emergency stop plunger, when asked why he replied "I'm one of the bravest drivers on the fleet, but even I'm braking by the 2nd bench down the platform!", we went round the loop and tried again, and stopped bang on the diamond  Happy times |
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Post by bazza55 on Mar 7, 2023 11:10:48 GMT
“Bazaar”. I think you mean the extension of the CBTC from Becontree to Upminster both directions, Barking is already in the CBTC area. As to the poor state of point work what makes you say this , some speed restrictions have been lifted due to the CBTC, if a set of points had a speed restrictions before CBTC the restrictions would still apply. Mainly due to the amount of noise from the wheelsets and bogie / train movement going over them. Good to see the East Ham curve smoothed out though. |
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Post by gigabit on Mar 8, 2023 8:51:04 GMT
The trains go so quickly into the platforms on the Central Line sometimes I think they won’t stop!
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Post by bazza55 on Mar 12, 2023 20:44:51 GMT
IS the extension of CBTC to Upminster still on target for the end of this month?
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Post by Harsig on Mar 12, 2023 20:48:42 GMT
Sooner than that. Its scheduled for next weekend (18th/19th March).
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Post by Dstock7080 on Mar 12, 2023 21:47:48 GMT
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towerman
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Post by towerman on Mar 12, 2023 21:55:04 GMT
Maybe I’ve missed something,noticed the Richmond service is reversing at Whitechapel,thought the reversing facility was removed when it was made a two platform station.
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Post by Dstock7080 on Mar 12, 2023 22:02:19 GMT
It is still possible to reverse at Whitechapel, both east>west and west>east; either in the respective platforms or a long shunt ahead if a more frequent service is required.
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Post by rincew1nd on Mar 12, 2023 22:03:48 GMT
I suspect the trains will be continuing out of service in the new CBTC area, it is just the passenger service that is suspended.
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Post by spsmiler on Mar 13, 2023 16:54:24 GMT
The trains go so quickly into the platforms on the Central Line sometimes I think they won’t stop! Yes, at most subterranean stations the Central line trains enter at speeed ... but even faster (I suspect) are the Victoria line trains. Rapid transit / transport as it should be! Then there are the Piccadilly and Northern lines (yawn) (there is usually time enough for a quick nap before these reach the far end of the platform) |
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Post by spsmiler on Mar 17, 2023 11:26:01 GMT
So, this coming weekend this scene become history! (Eastbound approach to Upminster Bridge)  |
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Post by gigabit on Mar 17, 2023 11:43:50 GMT
Is there any update on CBTC to East Putney?
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Post by Dstock7080 on Mar 17, 2023 12:40:28 GMT
As mentioned earlier, equipment is currently being installed on this and to Stamford Brook.
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Post by roman80 on Mar 17, 2023 12:57:14 GMT
Prompted by the remarks on doors and dwell time at Earls Court in the adjacent posts:
The long Earls Court dwell times are more apparent, and more likely to occur, post SMA5 despite improved run times in the last working timetable release. Is there any plan to tighten these further?
Very common to see trains advertised as two or more minutes away from departure on the boards suddenly approach and dock at the platform.
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Post by Dstock7080 on Mar 17, 2023 13:08:42 GMT
Is there any plan to tighten these further? Next timetable change Monday 22 May, “minor adjustments Barking and Upminster areas”. |
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Post by bazza55 on Mar 17, 2023 16:03:39 GMT
For SMA 6 commissioning On 14 January there won’t be any District services on the entire Line until 10.30-10.45. Trains will then run empty from Stepney Green-Becontree until authorisation is received for passenger operation in CBTC SMA 6. 62mph 56mph will now be achievable in several locations: West Ham-Bromley WB Plaistow-Upton Park EB/WB Upton Park-East Ham EB/WB Upney-Becontree EB/WB (edit)- the maximum speed has been reduced slightly to 90kph/56mph as a problem with tag reading at the higher speed has been identified. Work has also just begun installing new track mounted transponder tags, axle counters and antenna masts between Fulham Broadway and Putney Bridge, Ravenscourt Park and Stamford Brook. Has a fix been identified to resolve the tag reading issue at 100kph? |
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Happy times 
