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Post by goonerkeith on Nov 18, 2015 20:51:18 GMT
I hope a kind District operator will kindly answer this question which is bugging me  I've noticed on various cab ride videos that there is a particularly steep gradient on leaving Bow Road eastbound. Half way up the slope is a signal. If you have to stop there, how do you pull away without rolling backwards seeing that the throttle and brake are on the same lever? |
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North End
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Post by North End on Nov 18, 2015 21:04:14 GMT
I hope a kind District operator will kindly answer this question which is bugging me I've noticed on various cab ride videos that there is a particularly steep gradient on leaving Bow Road eastbound. Half way up the slope is a signal. If you have to stop there, how do you pull away without rolling backwards seeing that the throttle and brake are on the same lever? You make sure you don't put the handle in off & release by mistake, and don't dwell in that position when moving off. Also sensible to make sure you haven't lost the pilot light whilst stopped, as that will cause the train to roll if you attempt to motor without it. On the Northern Line West Finchley southbound is the favourite place for this. On a 95 stock you can hold the train on the deadman (put it into a motoring position then twist the handle). Not sure if this works on D or S stocks, however I've always looked upon this as bad practice, as it's not really what the deadman is there for. |
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Post by Deleted on Nov 18, 2015 21:17:47 GMT
there is a particularly steep gradient on leaving Bow Road eastbound. The steepest gradient in use by passenger-carrying services on the Underground, apparently, at 1 in 32. Thus saith Video125 anyway, who (like R2-D2) have been known to make mistakes ... from time to time. |
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North End
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Post by North End on Nov 18, 2015 21:33:13 GMT
there is a particularly steep gradient on leaving Bow Road eastbound. The steepest gradient in use by passenger-carrying services on the Underground, apparently, at 1 in 32. Thus saith Video125 anyway, who (like R2-D2) have been known to make mistakes ... from time to time. I'll have to check the plans, but I'm sure there are some short steeper downhill sections on the Northern leaving certain tunnel platforms, albeit only very short. Bow Road may be the steepest of any real length though. Can't resist mentioning that the steepest gradient of all was the incline up to Stockwell Depot, abandoned since 1924. |
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Post by Deleted on Nov 18, 2015 22:50:38 GMT
Wasn't the incline at Stockwell abandoned in favour of the 'hoist' in c.1907?
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North End
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Post by North End on Nov 18, 2015 23:43:57 GMT
Wasn't the incline at Stockwell abandoned in favour of the 'hoist' in c.1907? Mostly yes, the lower section remained to provide access to the two newer sidings. The steepest part starts just upwards of the turnout tunnel leading to the sidings, which was some distance from the running lines, today the Victoria Line cuts through this part of the tunnel. I'm not sure if the remains of the incline to surface were used for any purpose after the lift was brought into use. |
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metman
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Post by metman on Nov 19, 2015 7:05:51 GMT
How does the roll back protection on all stock work then?
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Post by domh245 on Nov 19, 2015 8:16:27 GMT
I think that roll back protection will only trigger after 0.5m of backwards movement. Rolling back slightly when moving off from stationary shouldn't set it off.
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Post by Dstock7080 on Nov 19, 2015 8:18:14 GMT
How does the roll back protection on all stock work then? Runback protection operates at 0.5m movement. On D Stock to the rear only. On S Stock in Tripcock mode, to the rear. In INTER in either direction. |
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Post by piccboy on Nov 19, 2015 8:51:06 GMT
How does the roll back protection on all stock work then? Runback protection operates at 0.5m movement. On D Stock to the rear only. On S Stock in Tripcock mode, to the rear. In INTER in either direction. Also in reverse, to the front on S Stock. |
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Post by goonerkeith on Nov 19, 2015 10:53:34 GMT
Is 'runback protection' automatic or set by the operator when stopped on a slope?
To a layman like me, it sounds very much like a handbrake on a road vehicle or something very similar.
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Post by Dstock7080 on Nov 19, 2015 11:46:06 GMT
Is 'runback protection' automatic or set by the operator when stopped on a slope? Runback protection is automatic when the cab is active. |
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North End
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Post by North End on Nov 19, 2015 14:52:26 GMT
there is a particularly steep gradient on leaving Bow Road eastbound. The steepest gradient in use by passenger-carrying services on the Underground, apparently, at 1 in 32. Thus saith Video125 anyway, who (like R2-D2) have been known to make mistakes ... from time to time. Out of curiousity, I've had a look through the gradient plans. Falls steeper than 1 in 32 are common leaving many Tube platforms on the earlier lines. The Northern and Central lines offer some more extreme gradients, including: - Leaving Kennington NB City - 1 in 20 fall - Approaching Old Street SB - 1 in 20 fall - Leaving Borough SB - 1 in 24 fall - Central Line WB leaving British Museum - 1 in 25 fall - Leaving Oxford Circus EB - 1 in 25 fall - Leaving Notting Hill Gate WB - 1 in 25 fall - Leaving Marble Arch EB - 1 in 26 fall - Leaving Bank WB - 1 in 26 fall - Leaving Bank SB - 1 in 27 fall - Leaving Bond Street both roads - 1 in 27 fall - Leaving Queensway WB - 1 in 27 fall - Leaving Chancery Lane EB - 1 in 28 fall - Leaving Oxford Circus WB - 1 in 28 fall - Leaving TCR WB - 1 in 29 fall - At 3x locations between Angel and King's Cross NB - 1 in 29 fall Most of these last only for a very short distance however, typically around 50 metres or less. The JLE also get close, with numerous sections of 1 in 33 both rising and falling, including some sections extending over a sustained distance, in particular a length of over 500m rising at 1 in 33 approaching Bermondsey EB. I haven't managed to find any rising gradients steeper than in 1 in 32 however. |
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Post by trt on Nov 19, 2015 15:31:12 GMT
The fall was deliberate wasn't it? To get a bit of free return from the climb into the platform.
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Post by Deleted on Nov 19, 2015 16:43:57 GMT
Is 'runback protection' automatic or set by the operator when stopped on a slope? To a layman like me, it sounds very much like a handbrake on a road vehicle or something very similar. Ah, no, it is quite different, it is an emergency safety measure, rather than something to hold the train on: www.districtdave.co.uk/html/runback_protection.htmlWhen the system detects that the train has been rolling backwards for a distance of 0.5 m it is deemed that the train is running away or is otherwise out of control of the operator and a brake application is demanded, bringing the train to a stand. It is used to stop a train after it has begun moving in the wrong direction, rather than to keep it stationary. |
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Post by Deleted on Nov 19, 2015 16:47:15 GMT
The fall was deliberate wasn't it? To get a bit of free return from the climb into the platform. Yes it was, to help the train pick up speed on the way out. As you rightly say, it gets something back from the climb in - the primary purpose of which was to scrub speed off for the stop. |
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class411
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Post by class411 on Nov 19, 2015 17:23:13 GMT
This may be a false memory, because if I saw it I would have been around seven, but I distinctly 'remember' an extremely short, extremely steep 'ramp' on the Central line at Greenford.
Is there such a 'ramp', there?
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Post by John Tuthill on Nov 19, 2015 17:53:49 GMT
The fall was deliberate wasn't it? To get a bit of free return from the climb into the platform. Yes it was, to help the train pick up speed on the way out. As you rightly say, it gets something back from the climb in - the primary purpose of which was to scrub speed off for the stop. And to assist acceleration on departure |
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rincew1nd
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Post by rincew1nd on Nov 19, 2015 19:08:20 GMT
The fall was deliberate wasn't it? To get a bit of free return from the climb into the platform. I seem to recall that the Glasgow subway was built specifically with a rise into the platforms and a fall out of them; to make things easier on the original cable-hauled system. |
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Post by Chris M on Nov 19, 2015 19:29:13 GMT
This is all from a vague memory of a very old thread (sufficiently old that Dave was commenting on it iirc) so treat it with caution, but I believe there is a set of catch or trap points on the District Line, I think somewhere near Tower Hill or Minories, where there is the steepest gradient on the network. It's extremely steep (something on the order of 1 in 3 or 1 in 4) but it's only a few centimetres long and only on one rail. It's purpose is to allow the right hand wheels to pass over the normal left hand running rail without needing a gap in that rail.
I certainly hope that it has never been used in passenger service.
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lt
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Post by lt on Nov 19, 2015 20:03:43 GMT
This may be a false memory, because if I saw it I would have been around seven, but I distinctly 'remember' an extremely short, extremely steep 'ramp' on the Central line at Greenford. Is there such a 'ramp', there? On departure London bound trains have to climb over the Greenford West Junction, the east bound also drops into the platform where it also crosses the same line with the Paddington push and pull rising up between them. |
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Post by Dstock7080 on Nov 20, 2015 11:48:36 GMT
The steepest gradient in use by passenger-carrying services on the Underground, apparently, at 1 in 32. Thus saith Video125 anyway, who (like R2-D2) have been known to make mistakes ... from time to time. District Line Driving Technique Guidance Diagram, say 1 in 38 rise, around 320m . Ravenscourt Park-Hammersmith EB 1 in 35 fall. Earl's Court-West Kensington WB initially 1 in 29 fall, followed by 1 in 30 fall. Most 'Tube' station rise & falls (Yerkes) are standard 1 in 33 fall, although ex-CSLR are 1 in 28/1 in 29, ex-CLR also 1 in 29/1 in 30 . |
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Post by abe on Nov 23, 2015 8:17:50 GMT
Another benefit of the 'humped' profile at many tube stations was that it reduced the depth of the lift shaft, meaning less excavation and (slightly) quicker access.
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Post by superteacher on Nov 25, 2015 22:56:12 GMT
Many years ago, there was a trailing crossover on the Bow Road slope which was regularly used to reverse trains off peak.
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Post by roythebus on Dec 6, 2015 12:16:55 GMT
With the old stock, the guard had to apply the rear handbrake if a train was detained at the signals on that climb. R stock was fitted with an additional handbrake in the guard's position on the west end driving cars for this reason.
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