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Post by Deleted on Jul 4, 2018 23:49:38 GMT
First thread... now time for making a fool of myself. I'm intrigued why sometimes on the Picc trains enter the platforms sometimes so slowly. There is significant braking in the tunnel sections and crawls into the platforms... Some of the Bakerloo line drivers seem to be attempting to break the sound barrier when entering the platform but on the Picc it's significantly slower. Then there's the odd driver who flies into the platform, so it's not something to do with the braking arcs? Surely this is slowing down the service? I can understand on open air stations to prevent wheel flats.. but tunnel sections - is there a reason?
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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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North End
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Post by North End on Jul 5, 2018 0:39:14 GMT
First thread... now time for making a fool of myself. I'm intrigued why sometimes on the Picc trains enter the platforms sometimes so slowly. There is significant braking in the tunnel sections and crawls into the platforms... Some of the Bakerloo line drivers seem to be attempting to break the sound barrier when entering the platform but on the Picc it's significantly slower. Then there's the odd driver who flies into the platform, so it's not something to do with the braking arcs? Surely this is slowing down the service? I can understand on open air stations to prevent wheel flats.. but tunnel sections - is there a reason? I get the impression the Picc has become a little over defensive in the last decade. Certainly I’ve noticed some pretty appalling driving on there recently. There are a number of possible reasons for this. Certainly it’s quite possible to enter tunnel platforms at 30-35 mph unless there’s a lower speed limit or some other reason. Anything below 30 and it may (or at least should) get flagged up during a competence assurance assessment.
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Post by Deleted on Jul 5, 2018 0:53:53 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?
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Post by PiccNT on Jul 5, 2018 1:42:30 GMT
We have two draw up signals, PJ320 halfway down platform 4 at Arnos Grove WB and L100 just prior to entering Kings X WB but they will only be active if there is a conflicting move taking place, both there to protect the converging junction ahead. I'm a bit of a flyer myself and would normally hit the platform at around 30mph. I do travel and have travelled with a lot of drivers on my line and North End is right, there are some drivers that don't appear to be able to drive at line speed and are over cautious coming into platforms.
It depends of course what time of day you're talking about. Plus we seem to be having no end of issues that results in driving "stick to stick" so that is maybe part of it also.
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Post by MoreToJack on Jul 5, 2018 1:46:22 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? Of course, none the draw ups still exist at OP and instead there is the (unique for LU) Variable Speed Signage (VSS) system.
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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 superteacher on Jul 5, 2018 6:59:29 GMT
Mainly it’s down to overly defensive driving. There have been very little signalling changes since the 80s and back then trains would fly into platforms. Unnecessary speed limits have also been implemented in places. I can’t believe how slow the trains enter the tunnel at Barons Court these days. I miss the days when it was full pelt into the tunnel down to Earls Court. There’s also Kings Cross southbound, where trains just seem to poodle in save for the odd driver.
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rincew1nd
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Post by rincew1nd on Jul 5, 2018 7:50:32 GMT
There's a fine fine line between overly-bold, defensive and excessively-cautious. I noticed two extremes the other day on the big railway: Click here if embedded tweet fails to display.
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Post by superteacher on Jul 5, 2018 8:03:34 GMT
There is a different culture nowadays. Many years ago the timetables were less forgiving and if you drove slowly you would run late. The mantra then was to enter platforms quixk and brake later.
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Post by Deleted on Jul 5, 2018 9:25:43 GMT
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!
Ahhhh Hopefully you were interested all the same There did used to be OP280, OP290, OP300, OP600 and OP700, but as MoreToJack says, all gone now
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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 A60stock on Jul 5, 2018 10:49:08 GMT
Ive also noticed another thing, on the shared sections with the district and met lines. I have used Eastcote station many times and notice how the s8 stock rushes into the platform at full pelt whilst the 73 stock comes in significantly slower? Is there a reason for this?
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Post by PiccNT on Jul 5, 2018 11:04:10 GMT
Mainly it’s down to overly defensive driving. There have been very little signalling changes since the 80s and back then trains would fly into platforms. Unnecessary speed limits have also been implemented in places. I can’t believe how slow the trains enter the tunnel at Barons Court these days. I miss the days when it was full pelt into the tunnel down to Earls Court. There’s also Kings Cross southbound, where trains just seem to poodle in save for the odd driver. There are some drivers that do enter the tunnel full pelt. They then fail the 25mph timing section and then SPaD A655! Ive also noticed another thing, on the shared sections with the district and met lines. I have used Eastcote station many times and notice how the s8 stock rushes into the platform at full pelt whilst the 73 stock comes in significantly slower? Is there a reason for this? The S stock trains have a higher speed limit than our trains plus their brakes are less erratic than ours! All station starters between Eastcote and Hillingdon do not clear until you have berthed in the platform so probably T/Ops just making sure they do stop! <<superteacher: posts merged>>
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Post by rummer on Jul 5, 2018 11:14:09 GMT
I always hit the platforms at about 30mph any faster than that you couldn't trust the 73 brakes
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Post by Deleted on Jul 5, 2018 11:17:36 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 superteacher on Jul 5, 2018 11:23:28 GMT
I always hit the platforms at about 30mph any faster than that you couldn't trust the 73 brakes Are the brakes less effective than they used to be?
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Post by PiccNT on Jul 5, 2018 12:20:59 GMT
I always hit the platforms at about 30mph any faster than that you couldn't trust the 73 brakes Are the brakes less effective than they used to be? That's probably a question for Fish. The main issue is that no two trains are the same and driving at the other end of the same train is also not the same. Added to that, the performance of the motors dictates to an extent the performance of the rheostat brakes. Theoretically, if we start braking when the speed of the train is above around 21mph, the rheo brake replaces the friction brake on the 4 motor cars. Sometimes this is the case, sometimes it isn't. Some trains the rheo brakes don't work at all. Also, if you release the brakes halfway down the platform, you get a surge when the rheos release and it takes a couple of seconds (seems longer) for the friction brakes to apply. It doesn't take long to get a feel for the train and what it's likely to do but sometimes, the unexpected happens so it's good to err on the side of safety.
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Tom
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Post by Tom on Jul 5, 2018 21:16:10 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! The author of that paper (JP) interviewed me for my job in the Design Office.
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Post by nig on Jul 12, 2018 15:24:38 GMT
Are the brakes less effective than they used to be? That's probably a question for Fish. The main issue is that no two trains are the same and driving at the other end of the same train is also not the same. Added to that, the performance of the motors dictates to an extent the performance of the rheostat brakes. Theoretically, if we start braking when the speed of the train is above around 21mph, the rheo brake replaces the friction brake on the 4 motor cars. Sometimes this is the case, sometimes it isn't. Some trains the rheo brakes don't work at all. Also, if you release the brakes halfway down the platform, you get a surge when the rheos release and it takes a couple of seconds (seems longer) for the friction brakes to apply. It doesn't take long to get a feel for the train and what it's likely to do but sometimes, the unexpected happens so it's good to err on the side of safety. if you release the brakes halfway down platform how do you get a surge surley all the brakes release so friction brake won't apply there is lots of slow drivers on picadilly line at moment not sure if its because of the training new trian ops or just a lot of defensive driving i was taught and still do enter the platform up to 40 mph depends on station service 4 reducing it till come to a stop in off and release some trains take longer to stop once rheos release and friction brake comes on at 8 mph but you soon get the feel for the train if you need to go into off and release halfway down platforms your going too slow
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North End
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Post by North End on Jul 12, 2018 15:31:34 GMT
That's probably a question for Fish. The main issue is that no two trains are the same and driving at the other end of the same train is also not the same. Added to that, the performance of the motors dictates to an extent the performance of the rheostat brakes. Theoretically, if we start braking when the speed of the train is above around 21mph, the rheo brake replaces the friction brake on the 4 motor cars. Sometimes this is the case, sometimes it isn't. Some trains the rheo brakes don't work at all. Also, if you release the brakes halfway down the platform, you get a surge when the rheos release and it takes a couple of seconds (seems longer) for the friction brakes to apply. It doesn't take long to get a feel for the train and what it's likely to do but sometimes, the unexpected happens so it's good to err on the side of safety. if you release the brakes halfway down platform how do you get a surge surley all the brakes release so friction brake won't apply there is lots of slow drivers on picadilly line at moment not sure if its because of the training new trian ops or just a lot of defensive driving i was taught and still do enter the platform up to 40 mph depends on station service 4 reducing it till come to a stop in off and release some trains take longer to stop once rheos release and friction brake comes on at 8 mph but you soon get the feel for the train if you need to go into off and release halfway down platforms your going too slow Must say that ties in with my thinking - the only time I’d fully release brakes during a station stop is during poor adhesion, otherwise I tend to go with throw it all on and take a bit off as necessary. The only other exception is if there’s a signal or trainstop there. Thinking fondly back to Brent Cross where the southbound platform ramp could be hit at 40mph even in the wet!
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Post by superteacher on Jul 12, 2018 15:32:53 GMT
Here’s a video from the late 80s. Go to 1:30 and you will see a Piccadilly Line 1973 stock entering Kings Cross westbound. Seems a bit quicker than nowadays.
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Post by nig on Jul 12, 2018 22:16:34 GMT
Here’s a video from the late 80s. Go to 1:30 and you will see a Piccadilly Line 1973 stock entering Kings Cross westbound. Seems a bit quicker than nowadays. There is a 35 mph speed limit now with clear signals but most drivers seem to come in a lot slower maybe they should use that as a training video
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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 rheostar on Jul 15, 2018 9:31:53 GMT
Are the brakes less effective than they used to be? That's probably a question for Fish. The main issue is that no two trains are the same and driving at the other end of the same train is also not the same. Added to that, the performance of the motors dictates to an extent the performance of the rheostat brakes. Theoretically, if we start braking when the speed of the train is above around 21mph, the rheo brake replaces the friction brake on the 4 motor cars. Sometimes this is the case, sometimes it isn't. Some trains the rheo brakes don't work at all. Also, if you release the brakes halfway down the platform, you get a surge when the rheos release and it takes a couple of seconds (seems longer) for the friction brakes to apply. It doesn't take long to get a feel for the train and what it's likely to do but sometimes, the unexpected happens so it's good to err on the side of safety. From memory, the rheostat brake comes on at 37 mph and goes off at 7 mph. When I was a road trainer, I'd train new drivers to enter a platform fast enough so that they wouldn't have to go into 'off and release' half way down the platform, thus avoiding the 73 stock's little foible of all of the brakes going off and the train seeming to surge forward. That surge catches a lot of inexperienced drivers out.
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Post by davethewomble on Jul 18, 2018 13:43:17 GMT
From memory, the rheostat brake comes on at 37 mph and goes off at 7 mph. Does that mean it's friction brakes only outside that range?
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Post by nig on Jul 18, 2018 15:34:43 GMT
From memory, the rheostat brake comes on at 37 mph and goes off at 7 mph. Does that mean it's friction brakes only outside that range? When brakes are applied all friction brakes come on if speed is between 21 and 44 ( might be higher than 44 can't quite rember but not definetly not 37 ) mph and all is well the rheostatic brake will come on in 4 motor cars and stay on till around 8mph or brakes are realised . They stop at a constant rate and if apply more or less brakes it's only the trailer cars friction brake that work .. where you get the surge people talk about is when you put brake into emergency rheostatic brake comes off and all friction brakes apply but train seems to have a little delay when rheostatic comes off and other brakes apply The other surge is if you go into off and realese below 21 mph then brake again you was used to rheostatic brake which is fairly good but now your just on friction brake and depending on train aren't always that good so say a service 2 now won't be as good as what it was with rheostatic hence feels like a surge That's why we was taught not to go into off and realese halfway down platforms unless you have to Although the friction brake is a lot better than it used to be. But drivers seem to be going a lot slower into platforms these days
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Post by Chris M on Jul 18, 2018 18:49:40 GMT
So the obvious question is what slows the train down if it's going more than 44 (or whatever) mph?
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Post by commuter on Jul 18, 2018 19:22:36 GMT
One key difference between the Piccadilly and the Bakerloo however is that most stations on the Picc have multi-home signals whereby if a train is departing a platform another train can follow up quite close behind. The Bakerloo only has ordinary running signals between stations (excluding those places with drawups), meaning that if a train has departed a platform it will be a bit longer before the following train enters the platform because it has further to travel and thus will have built up a bit more speed.
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Post by nig on Jul 18, 2018 21:25:03 GMT
So the obvious question is what slows the train down if it's going more than 44 (or whatever) mph? The westcode brake (friction brake ) All the friction brakes come on to begin with it's only when all conditions are met does rheostatic take over such as speed and if motors aren't working on one motor car that car will stop on the friction brake
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