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Post by londonstuff on Feb 20, 2012 17:59:31 GMT
Does this not reduce the capacity of the line, always having a red signal at the headwall? If the section ahead it clear, just go! The examples I've seen there's a good 2-3 minutes between trains - it seems silly and arbitrary to wait around when the next section is unoccupied. I would have thought fixed signals would have gone and been replaced with in-cab signalling in any case. How is the signalling upgrade going? I only ask because I've used the Vic line quite a lot recently and although the speed of trains seems quick I've not yet seen any stations with the blue aspect showing and the red aspect seems to show for much longer after a train has departed than I'd expect - in fact they seem to stay red until well after the next train has entered the platform. I know this is a generalisation but seems to happen much more often than with the old signalling system. When will the new timetable be introduced? The reason signals are always red until the next train has entered the platform is that the station starter signals are approach controlled. This means that when the train enters the berth track circuit, a timer starts. When the timer expires (think these are in the order of 10-20s, depending on track circuit length), the starter signal may clear, providing the track ahead is also in a state to allow it to do so. This is in order that a train entering a platform will always see a red aspect, and ATP indications to the operator will indicate the station is to be stopped at. The ATP also gives protection against station overruns in this configuration. Believe the new timetable will be introduced in May.
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Post by Deleted on Feb 22, 2012 9:33:41 GMT
Does this not reduce the capacity of the line, always having a red signal at the headwall? If the section ahead it clear, just go! The examples I've seen there's a good 2-3 minutes between trains - it seems silly and arbitrary to wait around when the next section is unoccupied. I would have thought fixed signals would have gone and been replaced with in-cab signalling in any case. In a word, no. The approach locking timer, as stated earlier is only 10-20s from the train entering the berth track circuit as it enters the platform. By the time the doors have been cycled, with a typical 20-30s dwell time, the signal will have cleared. If they are held longer than this, this will be due to either the SCC holding the signal to regulate gaps in the service, or genuine congestion backing trains up ahead.
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Tom
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Post by Tom on Feb 26, 2012 14:28:31 GMT
That sounds like a good case of the standards being applied without a thought as to why. Normally we have a speed check on starters to ensure that a train is at 35km/h or less so as to avoid compromising signal overlaps in the section ahead. If you have a continuous ATP system there is no need to enforce the speed check as the ATP ensures overlaps can't be compromised.
Full marks to invensys for not thinking, nor even remembering that they took the platform speed checks out on the Central line after ATP was introduced!
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Post by Deleted on Feb 26, 2012 17:41:58 GMT
That sounds like a good case of the standards being applied without a thought as to why. Normally we have a speed check on starters to ensure that a train is at 35km/h or less so as to avoid compromising signal overlaps in the section ahead. If you have a continuous ATP system there is no need to enforce the speed check as the ATP ensures overlaps can't be compromised. Full marks to invensys for not thinking, nor even remembering that they took the platform speed checks out on the Central line after ATP was introduced! ...mmm....but who wrote the specification that Invensys worked to.....
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Tom
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Post by Tom on Feb 26, 2012 21:07:23 GMT
It's the old 'jumping off a cliff' scenario; just because it's been specified doesn't mean it's the right thing to do.
We constantly get told to challenge standards which are inappropriate; it's strange that contractors are not similarly encouraged to do so. My experiences in dealing with Invensys does suggest that their criteria for applying or ignoring standards does tend to be what is the right commercial decision, more than what is the right engineering decision.
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Post by Deleted on Feb 26, 2012 22:18:23 GMT
My experience of being both a contractor and client is that as a contractor we are constantly told not to challenge the client because he is always right and he pays the bills and as the client we constantly critise the contractor for not being good enough at challenging the client but only do it when it could save money but then we may decide not to take the offer as it could be embarrassing because we didn't think of it before we let the contract
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Post by Deleted on Feb 27, 2012 11:32:07 GMT
That sounds like a good case of the standards being applied without a thought as to why. Normally we have a speed check on starters to ensure that a train is at 35km/h or less so as to avoid compromising signal overlaps in the section ahead. If you have a continuous ATP system there is no need to enforce the speed check as the ATP ensures overlaps can't be compromised. Full marks to invensys for not thinking, nor even remembering that they took the platform speed checks out on the Central line after ATP was introduced! They are not speed checks, they are to ensure that the ATP enforces stopping at the platform, and gives the associated target speed indications for stopping at the platform. Without approach locking, if the block ahead were proceed and not occupied, the train could theoretically pass through the platform at line speed in Protected Manual.
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North End
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Post by North End on Feb 27, 2012 12:33:57 GMT
That sounds like a good case of the standards being applied without a thought as to why. Normally we have a speed check on starters to ensure that a train is at 35km/h or less so as to avoid compromising signal overlaps in the section ahead. If you have a continuous ATP system there is no need to enforce the speed check as the ATP ensures overlaps can't be compromised. Full marks to invensys for not thinking, nor even remembering that they took the platform speed checks out on the Central line after ATP was introduced! They are not speed checks, they are to ensure that the ATP enforces stopping at the platform, and gives the associated target speed indications for stopping at the platform. Without approach locking, if the block ahead were proceed and not occupied, the train could theoretically pass through the platform at line speed in Protected Manual. I remember some years ago, in the days when Woodford to Hainault used to close at 20:00, there was weekend engineering work Leytonstone to Hainault via Newbury Park. The Hainault service was revised to run via Woodford, after 20:00 running non-stop from Woodford to Hainault. Certainly on this occasion trains were passing through the platforms at full speed in coded manual - then 100kph! I can't see why, with ATP, there is any need for station stops to be enforced. The line speed is being constantly monitored, and as soon as the train approaches restrictive signals (in modern terms the "limit of movement authority") the system will ensure the train will be brought under control.
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Post by plasmid on Feb 27, 2012 16:37:15 GMT
Tube trains are designed to push air through the tunnels so on that basis a tube train running through a station on the Vic Line at 50mph would be enough of an air force to either push you back or suck you in.
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Post by Deleted on Feb 27, 2012 22:59:50 GMT
Tube trains are designed to push air through the tunnels so on that basis a tube train running through a station on the Vic Line at 50mph would be enough of an air force to either push you back or suck you in. That is one of the reasons it is there. The hazard of paggengers being sucked onto the track in a tube is much greater than in open platforms, especially ones that were closed for engineering works. If possible, hazards should be mitigated by automated systems, rather than relying on procedure. Also, it helps avoid the service disruption you would get from an overrunning (long stopping) train.
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Post by Deleted on Mar 1, 2012 18:28:48 GMT
T/ops do not drive in PM on the main railway unless thats all the the train is capable of ding because of a defect. When the line has been fully asset replaced by the end of june this year, t/ops will be able to drive at full line speed in PM, where as at the moment they can only do 22kph in PM. Eventually even from the trip from seven sisters to northumberland park will be done in ATO, but that wont be until late this year or early next im led to believe.
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Post by jardine01 on Mar 1, 2012 18:56:24 GMT
Why do they want Seven sisters to Depot in ATO? These drivers will never drive the train at this rate surely in the Depot must be PM?
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Post by jamesb on Mar 1, 2012 19:13:07 GMT
I see that , as part of the new signalling, there are new ESPs on the platforms.
Why has it been deemed worth installing these on Victoria line platforms, when the devices were scrapped on the Jubilee line?
Noted that some Jubilee line stations have PEDs but not all of them do.
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Post by Deleted on Mar 1, 2012 19:28:08 GMT
Why do they want Seven sisters to Depot in ATO? These drivers will never drive the train at this rate surely in the Depot must be PM? LOL! @ jardine01, ATO and ATP are not only about speed. Signals also stop trains adopting the same paths etc. As you want an efficient system for getting train in and out of the depot, even if not at high speeds, ATO is one way of doing that. Does the stretch of track between Seven Sisters and the depot already have (the old) ATO in place? If so maybe it's approaching life expiration and so needs replacing. Regardless, having one signalling system means fewer systems to maintain and control.
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Post by bruce on Mar 1, 2012 22:28:01 GMT
1967 stock had to be driven in coded manual to and from the depot, maximum speed 22mph. I assume that the 09 stock has to be driven in PM.
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Post by Deleted on Mar 3, 2012 23:35:08 GMT
I'll answer all since my last post as best i can lol. The simple answer for why they want depot to seven sisters is to save time, this will be the one of the very lat things to be implemnted in the victoria line upgrade. In answer to the next question there are 4 EP's on each victoria line platform, not quite sure why they were scrapped on the jubileee, maybe they ran out of money because there whole upgrade was an expensive disaster!!
The peice of track between Seven Sisters and Depot is driven in PM and regardless of wether the old coded bit is in place it is not utilised, but from the sheds and the staff platform in the depot they drive in Restricted Manual (RM) up untill the outlet signals of Vn7 and VN8, where t/ops switch to protected manual (PM). For those that are interested the ATO system is called DTGR, Distance To Go Radio.
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