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Post by principlesdesigner on Nov 16, 2023 13:49:16 GMT
S Stock and 1972 Stock do indeed carry Track Circuit Operating Clips as they run over or alongside National Rail infrastructure. They must NOT be used on 4-rail current system track. Please could you explain why. Because they would have to pass over or under the negative conductor rail, and be very close to the positive conductor rail
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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 principlesdesigner on Feb 2, 2023 8:08:21 GMT
Acton yard?
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Post by principlesdesigner on Jan 31, 2023 10:13:17 GMT
Ruislip depot?
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Post by principlesdesigner on Jan 30, 2023 10:47:45 GMT
I *think* XR uses Siemens Trainguard MT for ATP & ATO, Siemens Vicos for ATC, and Siemens Trainguard some-other-name for ATP and the whole lot makes for their CBTC; LU is all Thales Seltrac S40.
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Post by principlesdesigner on Oct 27, 2021 16:24:17 GMT
Was that a Central Line specific thing? I don't recall it in the standards. (And it's been several years since I've had access to a copy of the CLP Signalling Contract.) I seem to recall that it was also a requirement on the VLU
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Post by principlesdesigner on Oct 26, 2021 21:06:10 GMT
There was (is?) a rule that there had to be a signal every 1.1km
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Post by principlesdesigner on Jul 1, 2021 13:02:51 GMT
The primary location system for CBTC is the VOBC on the train (computers) reporting their position to the VCC (computers), using the RFID tags on the track for position information. The back up uses axle counters which again feature a microprocessor based system (and yes, if you want to interrogate it, you need a computer). One of the weaknesses with an axle counter system is that you can leave a detection head off the rails and it will still show the section as unoccupied (at least until the first train). Are you sure about this? Many axle counter systems use the rail's presence to detect the absence of an axle
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Post by principlesdesigner on Apr 16, 2021 15:48:40 GMT
And of course the emergency trainstop
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Post by principlesdesigner on Mar 26, 2021 16:39:42 GMT
They have been there ever since ATP/ATO operation was commissioned in the mid 90s. The white signal on the mainline indicates to the driver that the crossing is in order
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Post by principlesdesigner on Dec 23, 2019 11:05:30 GMT
D: Bridge outside Ruislip Gardens +1
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Post by principlesdesigner on Mar 27, 2019 13:29:27 GMT
+1
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Post by principlesdesigner on Aug 15, 2018 0:28:13 GMT
jacko1 That is correct! The GC was built to continental loading gauge, it was part of a master plan by Edward Watkin, who was chairman of the Met & GC
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Post by principlesdesigner on Aug 9, 2018 8:22:09 GMT
I could be wrong as it is many years since I have been in the SJW tunnels, 1989 ish, but I seem to recall that they were only headshunts.
SJW = St Johns Wood
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Post by principlesdesigner on Jul 26, 2018 7:11:51 GMT
What does a 'shunt move' actually mean? . A shunt move by using shunt signals, is a caution/restricted speed movement from either: - depot or siding to running line - running line to depot or siding - movement from one running line to another - movements within sidings Additionally, there is usually a very much reduced overlap, little or no flank protection etc.
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Post by principlesdesigner on Jul 13, 2018 0:37:33 GMT
tut - thanks for this, I am interested, and indeed started some work on the replacement of Edgware Road cabin, before the original proposal was scrapped!
Thanks tut, very interesting. I know John Phillips quite well.
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Post by principlesdesigner on Jul 12, 2018 0:20:09 GMT
Nah. They'd have canned it first thing this morning if they wanted to avoid negativity. 90 minute late start up and known issues with VOBC tags. It's no surprise that trains are losing over an hour on the Hammersmith branch. Sorry, I'm not trying to be pedantic here - I just looked at this thread for the first time today, and can't understand what is meant by 'the Hammersmith branch'. (Probably because I didn't read the thread from which this was split.) I cannot identify any piece of railway that would qualify as 'Hammersmith branch'. Unless you mean all the District line going west from Earl's Court that does not go to Wimbledon. Or possibly the HC&C line from Edgeware Road. But I used most of the services from Hammersmith and apart from some 5 min waits at Edgeware Road itself I can't think of anywhere that trains could be losing over an hour. The services just aren't that unreliable. It may just be the heat making me extra dense. ETA: I'm assuming the Piccadilly line does not count as a branch as there's no other line west through Hammersmith. Edgeware?
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Post by principlesdesigner on Jul 11, 2018 9:08:23 GMT
The balises are placed at known locations along the track and, when read, are used to reset the train's distance measuring equipment, which if not done (fairly) regularly, will lead to the train becoming "lost", as the potential error building up will be too great. More balises are required on the approaches to stations to ensure an accurate ATO stop. The balises perform a similar function to the transpositions in the loops on the Seltrac system, and the Absolute Position References, APRs on the Victoria line
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Post by principlesdesigner on Jul 5, 2018 10:05:37 GMT
tut - thanks for this, I am interested, and indeed started some work on the replacement of Edgware Road cabin, before the original proposal was scrapped!
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Post by principlesdesigner on Jul 5, 2018 3:37:30 GMT
This will be where "draw-up" or speed controlled signals are provided. Basically, where there are short sections, the full speed overlap extends too far ahead, so the following train would not be able to enter the platform, so, the signals before the station, home signals, are held at red until the train is proved to be travelling slowly enough for the reduced starter overlap. Often, there is either an additional signal, or trainstop provided in the platform for speed control purposes, and will be numbered with an extra 0 e.g. OP200, so that the driver is aware of their purpose. I had the thought too, but I'm not sure there are any draw ups in the tunnel sections of the Picc. Obviously there's some at Arnos Grove, but that isn't in tunnel of course.
There was never an OP200, 20 lever controls points and OP2 is the inner rail home to platform 4 - or was it just an example? tut it was just an example I dreamed up!
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Post by principlesdesigner on Jul 5, 2018 0:04:25 GMT
This will be where "draw-up" or speed controlled signals are provided. Basically, where there are short sections, the full speed overlap extends too far ahead, so the following train would not be able to enter the platform, so, the signals before the station, home signals, are held at red until the train is proved to be travelling slowly enough for the reduced starter overlap. Often, there is either an additional signal, or trainstop provided in the platform for speed control purposes, and will be numbered with an extra 0 e.g. OP200, so that the driver is aware of their purpose.
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Post by principlesdesigner on Jun 27, 2018 6:38:40 GMT
Well the 96 stock already seems to be falling apart now thanks to TBTC, so the 95 stock probably won't be far behind if they start running them at 60mph. A lot of people praise TBTC but imo it isn't a very good way of signalling a tube line. The best ATO system is still the Central line one. It recovers quickly, does a good job keeping trains to time and what also makes it far better is the fact that unlike TBTC, it keeps trains moving not holding them close together in a queue; Yes I know sometimes you can see a train ahead on the Central, but there is less likelyhood of stopping as the trains are kept further apart. As a passenger I would rather be moving not sitting in a tunnel every 30 seconds because of a train 1m in front of me. TBTC can run a lot of trains but what good is it when they just keep sitting in tunnels when there are too many trains on the line. Central line Ato - Gets you from A to B asap TBTC - Can hold a lot more trains in a queue. I know which I prefer. Keeping this post in line with the subject though, I remember when the Northern was manually driven and the train would pull out of Euston City NB and accelerate to about 20/25mph. Obviously because of Camden being ahead trains could be held outside and occasionally the train would stop at a signal. However most of the time a good manual driver would drive at the perfect speed to give time for the signal ahead to clear and the train would go straight in to Camden platform. Since TBTC every time I have used the line around that section, the train accelerates to the full permitted speed only to then slow down and be held at the signal... How is this an improvement?! Moving block is a great way of getting you into trouble quickly when service delays occur, as you have correctly observed!The best ATO system is still the Central line one. It recovers quickly, does a good job keeping trains to time and what also makes it far better is the fact that unlike TBTC, it keeps trains moving not holding them close together in a queue I beg to differ. DTG-r on the Victoria Line delivers startling service intervals and swift transit. Both are good systems, DTG-R was an evolution of Westinghouse's previous products and experience. Both are essentially fixed block, DTG-R differing from the previous generation in that the system is brake assured therefore calculated overlaps are not required, just a nominal (50m) safety distance which allows the train to draw up to the marker boards.
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Post by principlesdesigner on Jun 27, 2018 5:21:25 GMT
+1
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Post by principlesdesigner on May 14, 2018 3:08:18 GMT
The Bakerloo line is not planned to be operated as a driverless line
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Post by principlesdesigner on May 10, 2018 5:45:23 GMT
Was all the yellows installed post Moorgate disaster as a warning it’s going into a dead end tunnel I’m sure Liverpool Street siding on the Central was / has the same set up It did indeed, as did Marble Arch
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Post by principlesdesigner on May 8, 2018 9:28:04 GMT
No lamp proving is provided except for junction indicators as trainstops / ATP will enforce a dark signal
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Post by principlesdesigner on Apr 11, 2018 5:55:10 GMT
LU has 125hz and 33 1/3hz and 50hz track circuits I always found 33 1/3hz tracks gave the biggest shock That makes some sense, the skin effect at 33.33 Hz about 13mm whilst at 125 Hz it's only 7mm (approximate). There's probably also some bio-electrical effects that I'm not aware of, too. I've always found the 33 1/3Hz tracks the most evil!
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Post by principlesdesigner on Apr 10, 2018 0:12:16 GMT
15v through the running rails if memory serves Until you take the relay connection off, when it goes to 100v!
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Post by principlesdesigner on Apr 9, 2018 8:17:53 GMT
2 St Marks Square, Venice?
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Post by principlesdesigner on Apr 5, 2018 4:26:30 GMT
Is it between White city & East Acton ? +1
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