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Post by vic09 on Mar 16, 2012 7:33:59 GMT
Hello this is my first post.
There was something that was bugging me for ages, and I just wanted to know why. On the Victoria line, I used to love the section between Green park and Oxford Circus Northbound, it felt like you was flying along that track really fast. It also pulled in to Oxford circus really fast. Now theyve put in this new signalling it now comes in really slow like at Victoria. Also it now takes longer to get from station to station. Does
Anybody know why??
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Deleted
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Post by Deleted on Mar 16, 2012 10:14:46 GMT
It is a speed restriction for train headway purposes. The contract is performance based, which means in basic terms there is a trade off to be done between interstation runtimes (the time for a train to get from station A to station B) and platform re-occupation times (the time between train A starting from a platform to train B becoming stationary at the same platform).
Generally, increasing interstation run times (trains running slower), improves the platform re-occupation time, since slower trains can run closer together. Achieving good re-occupation times at these critical areas of the line is important if you want to achieve a good performance 'score'. Unfortunately, this sometimes has the side effect of slower interstation run times (trains running slower).
Hope that answers your question.
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Post by vic09 on Mar 16, 2012 15:43:00 GMT
Thanks for that do you know if it is permant or just temporary
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Post by alfie on Mar 16, 2012 18:19:32 GMT
It's all driven by scores. I've heard a legend, that once upon a time, railways moved people really fast, and moving people faster would help them..
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Deleted
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Post by Deleted on Mar 16, 2012 19:26:16 GMT
Has this anything to do regenerative breaking and load balancing? -By this I mean one train slowing and feeding power back as the other is taking power and accelerating?
XF
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Post by londonstuff on Mar 16, 2012 21:49:23 GMT
It is a speed restriction for train headway purposes. The contract is performance based, which means in basic terms there is a trade off to be done between interstation runtimes (the time for a train to get from station A to station B) and platform re-occupation times (the time between train A starting from a platform to train B becoming stationary at the same platform). Generally, increasing interstation run times (trains running slower), improves the platform re-occupation time, since slower trains can run closer together. Achieving good re-occupation times at these critical areas of the line is important if you want to achieve a good performance 'score'. Unfortunately, this sometimes has the side effect of slower interstation run times (trains running slower). Hope that answers your question. To a non-signal technician the new Victoria line signalling system seems very strange. I've mentioned on here before about the headwall signals always being red and how this must slow things down, only to be told be those in the know that it won't. However, I beg to disagree - I've been on the Vic a few times in the last couple of weeks, in peaks and out of peaks, on crowded trains and empty, northbound and southbound and often with 3 minute gaps between trains (I mention this last point only because the signalling presumably is then not held up by a train too closely in front). My observations are thus: The red aspect at each headwall remain at danger for much longer than it takes passengers to alight and board the majority of the time, leading to increased dwells. Often this is the case for over a minute or two. I was held at KX southbound the other day, with no disruption or any trains close ahead for about three minutes. This has happened several times and seems to be for no good reason. The blue aspects also seem to be very arbitrary with them appearing at some stations and not others, including some stations that don't even seem to have a blue aspect (Warren Street NB I think, but not sure). In general the trains do seem to be slower in the central area of the line but quicker in the stretches, e.g. Finsbury to H&Islington. I'm also absolutely surprised that, according to Diamond Geezer today, the new timetable isn't going to be implemented until March 2012. I know these things take time, but surely... The work has been ongoing with the Vic now since, what, 2008? 2009? with the early closures, etc. and from a casual viewpoint, apart from the new trains there doesn't seem to have been any measurable improvement, not least in journey time. I'm certainly not trying to be negative and would love those in the know - Dan and Racka? - to tell me that I'm wrong. |
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Post by jardine01 on Mar 16, 2012 22:22:03 GMT
At least the victoria line drives at a set speed not like the Jubilee line! Maybe once the whole line is under the new Distance to go Signaling it might be allot quicker?
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Post by vic09 on Mar 16, 2012 22:32:19 GMT
Yes good point I really do think that the Victoria is faster than the jubilee. I've allways said that the peds act as an illusion and make you think it's faster than what's its going. Once it gets outside thats it, it's like a snail.
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mrfs42
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Post by mrfs42 on Mar 16, 2012 23:03:51 GMT
To a non-signal technician the new Victoria line signalling system seems very strange. I've mentioned on here before about the headwall signals always being red and how this must slow things down, only to be told be those in the know that it won't. (takes a break from packing non-UndergrounD WTTs) - I recall that the current WTT has running and dwell times based on the previous WTT "allowing recovery while the new assets are bedding in". My observations are thus: The red aspect at each headwall remain at danger for much longer than it takes passengers to alight and board the majority of the time, leading to increased dwells. Often this is the case for over a minute or two. I was held at KX southbound the other day, with no disruption or any trains close ahead for about three minutes. This has happened several times and seems to be for no good reason. Well, you know what my thoughts are.. If the trains are running to a former set of intermediate times and are now a lot more nippy given that the regen can be switched on with the old girls being sent out to grass, it is only natural that the dwell times seem longer - the trains simply get there quicker! I presume that the starters are still held to time and will clear to timetable (rather than have the regulator intervene for each and every one) The blue aspects also seem to be very arbitrary with them appearing at some stations and not others, including some stations that don't even seem to have a blue aspect (Warren Street NB I think, but not sure). AFAIAA VWS 1425 (Warren St NB starter) *does* have a blue aspect; and as regards transition areas Pimlico SB starter (A394) will not have a blue aspect, as below there is still old-style signalling. In general the trains do seem to be slower in the central area of the line but quicker in the stretches, e.g. Finsbury to H&Islington. Presumably that is a function of still running to old dwell times? I'm also absolutely surprised that, according to Diamond Geezer today, the new timetable isn't going to be implemented until March 2012. I know these things take time, but surely... Having been very pleasantly surprised with the changes in Jubilee 11 compared to Jubilee 10, I await similar style developments on the Vic with interest. ..er.. don't you mean March 2013? Presumably that will allow for the new signalling to go to Brixton and then a suitable 'shakedown' period (washes mouth out with soap and water). |
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Post by jardine01 on Mar 17, 2012 7:50:06 GMT
The Victoria is the best line in terms of speed and power of the trains.
I don't get why the Jubilee line is so slow outside? The Central goes full speed outside
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Post by Deleted on Mar 17, 2012 8:33:31 GMT
There's another Vic closure 30/01-01/04. Presumably this will upgrade the new signals all the way to Brixton. there's then another 06-07/05 which is for the signalling to the depot. From memory, some time after that, but also in May, the new timetable will come into play. Can someone with insider knowledge confirm?
Edit; I've just read that Tfl forecast a 16% decrease in journey times. This must in part come through higher speeds once the new timetable is introduced.
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Post by Dstock7080 on Mar 17, 2012 10:03:44 GMT
New WTT34 scheduled to operate from 22 April.
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Post by superteacher on Mar 17, 2012 11:10:38 GMT
It's only relatively recently that the speed has been slowed from Green Park to Oxford Circus.
I don't buy this headway stuff though. Maybe in the peak when running a 30tph plus service, but 27tph off peak shouldn't require a slow down.
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Rich32
Staff Emeritus
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Post by Rich32 on Mar 17, 2012 18:44:12 GMT
To a non-signal technician the new Victoria line signalling system seems very strange. I've mentioned on here before about the headwall signals always being red and how this must slow things down, only to be told be those in the know that it won't. (takes a break from packing non-UndergrounD WTTs) - I recall that the current WTT has running and dwell times based on the previous WTT "allowing recovery while the new assets are bedding in". Well, you know what my thoughts are.. If the trains are running to a former set of intermediate times and are now a lot more nippy given that the regen can be switched on with the old girls being sent out to grass, it is only natural that the dwell times seem longer - the trains simply get there quicker! I presume that the starters are still held to time and will clear to timetable (rather than have the regulator intervene for each and every one) That from my observations is what is happening, although there are regulator interventions as observed, by quite a few red to green changes. Blue aspects are at most signal posts on the converted parts (WAL to PIM), but not all - HBY n/b station starter being one example. The appearance of a blue aspect will depend on whether there is an intermediate block marker between it and the next signal. No block marker, no need for a blue aspect (AIUI). <snip> In general the trains do seem to be slower in the central area of the line but quicker in the stretches, e.g. Finsbury to H&Islington. I'm also absolutely surprised that, according to Diamond Geezer today, the new timetable isn't going to be implemented until March 2012. I know these things take time, but surely... The work has been ongoing with the Vic now since, what, 2008? 2009? with the early closures, etc. and from a casual viewpoint, apart from the new trains there doesn't seem to have been any measurable improvement, not least in journey time. I'm certainly not trying to be negative and would love those in the know - Dan and Racka? - to tell me that I'm wrong. Apparently the new timetable in March 2013 will make use of the speedier timings, but the current one still sticks to the 67 timings, e.g 3/4 mins between Finsbury and Seven Sisters or Highbury, where in reality 90seconds/2mins is far more realistic. |
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Post by Deleted on Mar 17, 2012 19:37:04 GMT
Strangely enough, I was just looking at my Oyster history, and it showed that; using the line, more or less daily, from Victoria - Highbury & Islington (and vice versa) for the last few months, the average journey time is 16 mins versus 13 in the other direction. I presume this speed restriction isn't in place in the other direction then?
Also, I notice that I tend to be held in platforms for longer going Northbound (but that may be because I'm usually going home from work). ;D
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Post by plasmid on Mar 18, 2012 0:27:06 GMT
The Victoria is the best line in terms of speed and power of the trains. I don't get why the Jubilee line is so slow outside? The Central goes full speed outside You know the answer to that question but I'll write this down one last time. Central and Victoria line are fixed block, Jubilee is moving block. Jubilee isn't slow outside all the time, it just depends on direction of travel/time of day/amount of trains required for service/weather/delays etc. Sometimes the 96ts is slow out of Stratford, other times it's fast. Back on topic and I have nothing to add to this thread. |
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Post by Deleted on Mar 18, 2012 6:55:11 GMT
The Victoria is the best line in terms of speed and power of the trains. I don't get why the Jubilee line is so slow outside? The Central goes full speed outside You know the answer to that question but I'll write this down one last time. Central and Victoria line are fixed block, Jubilee is moving block. Jubilee isn't slow outside all the time, it just depends on direction of travel/time of day/amount of trains required for service/weather/delays etc. Sometimes the 96ts is slow out of Stratford, other times it's fast. Back on topic and I have nothing to add to this thread.
'plasmid' I don't think your post is in keeping with the spirit of this forum. I suggest you read the forum rules.
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Post by alfie on Mar 18, 2012 7:58:01 GMT
Sometimes the 96ts is slow out of Stratford, other times it's fast. Between NOG and Stratford I've always had it slow, whatever the factors are, crush loaded or empty, North or South, etc. I haven't been North of Baker Street on the Jubilee since I went to Stanmore a few years ago, so dunno about there.. |
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Post by 100andthirty on Mar 18, 2012 9:23:26 GMT
All three of the systems are controlled somewhat differently.
Victoria line is all in the tunnel so the acceleration rates and braking rates are high all the time. Currently the timetable doesn't take account of the improved performance compared with the old trains, and so the trains move rapidly between stations and then sometimes get held. This will change over the next few months.
Central runs with maximum acceleration and braking rates in the tunnel (but not quite as good as the Victoria) and lower braking rates in the open. However tunnel speed limits are usually lower in the tunnel than in the open. the Timetable takes account of the run times between stations, but if there are gaps, the trains can be held at stations.
Jubilee line ATO doesn't allow quite such good acceleration and braking rates as the other two. The control system is highly centralised and therefore speeds between stations can easily be varied in order to maintain spaces and to try and avoid outside stations. All the things that plasmid mentioned can affect all this, and variations in station stop time affect run times too.
Hope this helps
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Post by vic09 on Mar 18, 2012 9:39:39 GMT
Thanks for all of this. I was just thinking and green park to Oxford circus is the only section what has had to slow down with the new signalling, will there be anymore sections forced to slow down once the new signalling goes live.
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Post by Deleted on Mar 18, 2012 10:28:25 GMT
That's for all of this. I was just thinking and green park to Oxford circus is the only section what has had to slow down with the new signalling, will there be anymore sections forced to slow down once the new signalling goes live. Don't think there are any more areas where it will be noticably slower than today. |
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Post by vic09 on Mar 18, 2012 10:31:21 GMT
That's great thanks
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Post by 100andthirty on Mar 18, 2012 17:57:03 GMT
I may be repeating what's been said before, but the approach to Victoria NB has a PSR in order to allow trains to get close to the platform whilst the one in front is using up the extended dwell time that is a feature of this platform. If at all possible, it's better to keep the approaching train moving than to stop it and then restart it when the one in front sets off.
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Post by edwin on Mar 19, 2012 13:29:22 GMT
^^From a rail enthusiastics perspective that's a shame. I used to always love the way the 67TS would dart into the station right near the platform entrances at Victoria NB.
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Ben
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Post by Ben on Mar 23, 2012 11:51:00 GMT
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