|
|
Post by jamesb on Dec 3, 2017 17:05:18 GMT
When I stand on several District Line platforms, e.g. Westminster, I cannot see any obvious difference in the level of the track on the E/B vs the W/B. But when I am on a train, the W/B trains seem to tower over the E/B trains (at least from the level of the windows).
Is one track higher than the other? Or is it a visual illusion ?
|
|
|
|
Post by domh245 on Dec 3, 2017 17:54:51 GMT
I would think that the curvature of the track would be responsible for that. There may be some cant (or superelevation) to the rails which will cause the trains to lean towards the centre of the bend (although the nature of how the trains follow the track will also introduce some lean), although based on what you've written, that may not be the case, as if the trackbeds are the same height the E/B should be higher at the inner edge of the tracks, and the W/B lower at the inner edge. That said, I've just found a picture of Westminster Station which shows that one of the tracks is quite clearly lower than the other!  You can see that the conductor rail of the line nearest the camera is approximately level with that raised section next to it, which is below the level of the other track |
|
|
|
Post by John Tuthill on Dec 3, 2017 17:57:47 GMT
I would think that the curvature of the track would be responsible for that. There may be some cant (or superelevation) to the rails which will cause the trains to lean towards the centre of the bend (although the nature of how the trains follow the track will also introduce some lean), although based on what you've written, that may not be the case, as if the trackbeds are the same height the E/B should be higher at the inner edge of the tracks, and the W/B lower at the inner edge. That said, I've just found a picture of Westminster Station which shows that one of the tracks is quite clearly lower than the other! You can see that the conductor rail of the line nearest the camera is approximately level with that raised section next to it, which is below the level of the other track You beat me to it!!  |
|
|
|
Post by goldenarrow on Dec 3, 2017 18:10:33 GMT
The rail on the inner radius of the curve is set lower than the outer rail enabling the train to tilt explaining why trains seem to rise above each other because you will be facing the side of the opposite train that is either tilting down or up giving the impression of an elevation difference in track when it's just opposing levels on the individual rail although as mentioned above Westminster could be amplifying this effect with a height change. The southern end of the Met line platforms 2 and 3 take this to the extreme with a 15mph speed limit giving a severe tilt and subsequently giving a significant height difference when observing a train on the opposite track.
|
|
|
|
Post by norbitonflyer on Dec 3, 2017 20:07:28 GMT
The platforms are both at the same level but the tracks are canted so the trains lean into the curve. Consequently the floor of an eastbound train slopes up from the platform and the floor of a westbound train slopes down, resulting in a noticeable difference in height between the offsides of the trains.
|
|
|
|
Post by countryman on Dec 6, 2017 22:15:35 GMT
The rail on the inner radius of the curve is set lower than the outer rail enabling the train to tilt explaining why trains seem to rise above each other because you will be facing the side of the opposite train that is either tilting down or up giving the impression of an elevation difference in track when it's just opposing levels on the individual rail although as mentioned above Westminster could be amplifying this effect with a height change. The southern end of the Met line platforms 2 and 3 take this to the extreme with a 15mph speed limit giving a severe tilt and subsequently giving a significant height difference when observing a train on the opposite track. I don't know whether I missed something, but which Met line platforms 2 and 3 are being referred to? |
|
|
|
Post by goldenarrow on Dec 6, 2017 23:21:07 GMT
countryman, I was referring to the through platforms that lead to/from the City. The photo below is taken by myself from a back of a Northbound train at Platform 3 opposite Platform 2 showing the severity of the curve and lean enabling a line of sight right to the front of the train. 
|
|
|
|
Post by norbitonflyer on Dec 7, 2017 7:19:19 GMT
The southern end of the Met line platforms 2 and 3 take this to the extreme with a 15mph speed limit giving a severe tilt and subsequently giving a significant height difference when observing a train on the opposite track. I don't know whether I missed something, but which Met line platforms 2 and 3 are being referred to? Baker Street? |
|
metman
Global Moderator
5056 05/12/1961-23/04/2012 RIP
Posts: 7,421
|
Post by metman on Dec 7, 2017 7:36:25 GMT
Yes looks to be Baker Street.
|
|
