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Post by Deleted on Apr 5, 2009 21:09:58 GMT
ive always wondered this for my whole life, so i guess this would be a good time to ask, but has anyone else noticed these little slider control things at along the sides of the platforms by the track, what are they for? thanks
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mrfs42
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Post by mrfs42 on Apr 5, 2009 21:14:57 GMT
Do you mean the little white squares with a slot in them? There is a red block in the slot?
If so, I've always puzzled about them - I think they are something to do with the cant/superelevation. The red blocks form a series of datums for track measuring.
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Post by Deleted on Apr 5, 2009 21:19:08 GMT
ohhh thats what i meant, im not actually sure why i assumed they slid up and down the slot  thanks for the help |
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Post by Deleted on Apr 5, 2009 21:30:49 GMT
Agrees with mrfs42.
They can indeed be slid up/down via some sort of special screw/lock nut. I have noticed on the NR system, that when they are fixed to the platform supports, they seem to be at differing heights; not the actual slider, but the whole thing itself. I'm not sure if there is any reason for this, other than the fact the fixer people couldn't move the ballast, or very localised track geometry. Not that such wild differentials are noticeable when on the train.
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mrfs42
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Post by mrfs42 on Apr 5, 2009 21:32:02 GMT
The red things do slide, but I'm pretty sure that they then are locked into position. It is a long time since I've got up close to one, so I can't be sure.
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Post by upfast on Apr 5, 2009 21:46:14 GMT
I believe it is for when ballasting/track reformation is carried out to check that the track is not too high and cause trains to strike the platform.
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Post by stanmorek on Apr 19, 2009 13:00:16 GMT
The rail datum markers record both cant and track level and are used for checking if the track has moved or as guide for maintenance work. On the Central line platform tunnels I'm told gauge clearance is more critical than other areas.
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metman
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Post by metman on Apr 19, 2009 13:37:24 GMT
I've often wondered about them. I've seen them in the tunnels arround Baker Street, must be to do with rail height and clearance?
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thanks for the help
