Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 9, 2008 21:59:55 GMT
Can anyone out there please help in providing or confirming the reason why Finsbury Park (both Piccadilly and GN&C platforms) were built on a distinct 'hump'.
The station plans around the time the lines were opened show the location of the water hydraulic lifts (four on each line). According to the plan, the lines geographically face north at the station. The plans also show a water pipe coming from under the lifts, passing underneath the northern arm of the Wells Terrace subway and going westwards to a pumping station away from the Underground station in Wells Road (presumably now Wells Terrace?).
Other than suggesting this might be the reason for the 'hump', I haven't been able to establish any other reason for it.
Over to you .......... ?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 9, 2008 22:17:07 GMT
I asked about this a long time ago, and never got a substantive answer. I don't know if that was because no one knew or because no one who does know was on the forum at the time.
I do remember stories that the initial 67TS braking sensors had a LOT of trouble with the gradients and required some readjustments before they performed reliably.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 10, 2008 8:14:14 GMT
Also more interestingly is that Finsbury Park was a terminus for the Piccadilly, and thus at the time it didn't require a downward gradient to the North of the station. Unless of course it was always expected that the line would be extended?
|
|
Chris M
Global Moderator
Forum Quizmaster
Always happy to receive quiz ideas and pictures by email or PM
Posts: 19,407
|
Post by Chris M on Jul 10, 2008 13:51:00 GMT
Reading the RAIB report into the derailment between Mile End and Bethnal Green it mentioned that Mile End has been built on the "Hump station principle". The basis of this principle is that approaching trains are travelling on a rising gradient, aiding deceleration and the falling gradient for departing trains aids acceleration, thus allowing a faster throughput (Stratford Central Line is an extreme example of this). I don't know whether that is the case for Finsbury Park, but it is the first thing that comes to mind. Do any modern stations use this principle? If not was it found not to be that effective, or is it more expensive or something?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 10, 2008 17:28:35 GMT
Do any modern stations use this principle? If not was it found not to be that effective, or is it more expensive or something? I don't *think* it is an important factor as it once was, given that trains today are more powerful/efficient than they were when the Underground was first being designed, but I don't really know what the official line on it is. I have always assumed this was the reason for Finsbury Park being designed as it is, although it does seem to be quite an extreme example of it.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 10, 2008 19:11:10 GMT
I seem to remember reading that Finsbury Park platforms were profiled to keep the lift and staircase depth to a minimum - but I'm not entirely sure about that.
I'm fairly certain that Victoria line stations were deliberately designed with a hump, wherever it was possible to do so given the overall gradient profile and the need to squeeze in between other lines at some stations.
Don't know about the Jubilee extension though?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 10, 2008 19:15:19 GMT
Meant to add - the Central London Railway was built with significant humps to aid braking and accelerating (I think 1/60 arriving, 1/30 departing) which were made even steeper when the platforms were extended.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 10, 2008 19:54:35 GMT
Do any modern stations use this principle? If not was it found not to be that effective, or is it more expensive or something? I don't *think* it is an important factor as it once was, given that trains today are more powerful/efficient than they were when the Underground was first being designed, but I don't really know what the official line on it is. I have always assumed this was the reason for Finsbury Park being designed as it is, although it does seem to be quite an extreme example of it. Terminal 5 has a gradient on the way in westbound, although the way the signalling works means you have to slow down. The gradient is replicated eastbound, you get up to line speed fairly quickly.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 10, 2008 23:14:53 GMT
Terminal 5 has a gradient on the way in westbound, although the way the signalling works means you have to slow down. The gradient is replicated eastbound, you get up to line speed fairly quickly. Oh frell, I *loathe* that westbound one. I'd only done it once or twice and my I/O had got into the habit of not giving me instruction because I'd done everything else on the line countless times. I kept switching between parallel, series, shunt, off and release, and round again, trying to get the train up the hill but also keeping to the speed limits for the controlled signal and having time to stop if any of them don't drop off... Next time we went round he talked me through it. Knowing what a mess I'd made of it previously, I definitely paid full attention. So in a way it worked!
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 10, 2008 23:16:17 GMT
Other than suggesting this might be the reason for the 'hump', I haven't been able to establish any other reason for it. Over to you .......... ? Wait, wait - I *know* this one now...! The person drawing the station designs clearly hiccuped whilst drawing out the platform. *probably ought to stop drinking lemonade and go to bed*
|
|
|
Post by Tubeboy on Jul 10, 2008 23:40:46 GMT
Right, despite being very drunk, is this the normal gradient to aid deceleration and downward slope to aid acceleration?
|
|
|
Post by railtechnician on Jul 11, 2008 11:17:26 GMT
Right, despite being very drunk, is this the normal gradient to aid deceleration and downward slope to aid acceleration? I don't think it is, to my knowledge Finsbury Park station is unique in the way in which the platforms appear humped. My understanding has always been that the ideaused on the Central line was to run uphill into a level platform and downhill away from it and not to have the train berthed on a hump. There may be geological reasons why Finsbury park is the way it is because the ground around the tunnels is extremely wet which used to cause regular erosion of the T/T wires which I spent a lot of time repairing.
|
|
|
Post by ruislip on Jul 11, 2008 16:28:21 GMT
Also more interestingly is that Finsbury Park was a terminus for the Piccadilly, and thus at the time it didn't require a downward gradient to the North of the station. Unless of course it was always expected that the line would be extended? And for years the LNER kept the Underground Group from effecting a northward extension of the Picc from FP.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 11, 2008 19:53:55 GMT
As has already been stated somewhere above, the hump is indeed to simply aid deceleration and acceleration.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 11, 2008 20:07:55 GMT
As has already been stated somewhere above, the hump is indeed to simply aid deceleration and acceleration. But, as also stated above, these humps were usually in the tunnels, leaving a level platform. Why does FP have a hump in the platform tunnel? It may (or may not) be relevant that the FP platforms (both Picc and GN&C) were not built by the tube companies but by the Great Northern. Perhaps it just seemed like a good idea at the time.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 11, 2008 20:42:10 GMT
As has already been stated somewhere above, the hump is indeed to simply aid deceleration and acceleration. Having the hump *in* the platform can actually cause problems stopping since the train can start to run away from you because it's starting on the downhill as you're trying to stop. It always seems to me as if Finsbury was either taken to an extreme for some reason, or as if it was made by someone who didn't *quite* understand the principle behind the entry-incline/exit-decline idea. But perhaps in older stocks with different braking systems it wouldn't have been such a problem?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 11, 2008 21:49:09 GMT
Having the hump *in* the platform can actually cause problems stopping since the train can start to run away from you because it's starting on the downhill as you're trying to stop. Conversely, the incline leading to the crest of the hump allows you to scrub off most of your speed, reducing your momentum. You need to alter your braking technique for this type of platform to avoid experiencing the train 'running-away' towards the end of the platform. Don't allow Finsbury Pk to become your new nemesis, UG!
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 12, 2008 7:03:12 GMT
Conversely, the incline leading to the crest of the hump allows you to scrub off most of your speed, reducing your momentum. You need to alter your braking technique for this type of platform to avoid experiencing the train 'running-away' towards the end of the platform. Don't allow Finsbury Pk to become your new nemesis, UG! It hasn't *yet*, but I do tend to come to a much harder stop there because I know that I can't easily coast to a stop and have to stay in a braking position longer.
|
|
|
Post by suncloud on Jul 12, 2008 8:31:02 GMT
I can find no evidence to support this, but I am sure I've seen somewhere the hump was something to do with matching the profile of lines above... So i may be just making it up...
|
|
|
Post by Colin D on Jul 12, 2008 11:34:05 GMT
Do any modern stations use this principle? If not was it found not to be that effective, or is it more expensive or something? I don't *think* it is an important factor as it once was, given that trains today are more powerful/efficient than they were when the Underground was first being designed, but I don't really know what the official line on it is. I would think no matter how powerful and efficient the trains are getting, the "hump" principle would still work the same for aiding braking and acceleration somewhat.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 13, 2008 0:38:23 GMT
I would think no matter how powerful and efficient the trains are getting, the "hump" principle would still work the same for aiding braking and acceleration somewhat. Yes, somewhat - but a train built at the beginning of the tube service, such as the first Central line trains, presumably would be less efficient/powerful/I-know-what-I-mean than a current day one. Or at least, one would hope. Therefore, though it's still relevant, the degree to which it's relevant has changed? Then again it's nearly 2am and I could be talking absolute rubbish.
|
|