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| White points and crossings? 27/07/2011 at 21:37 #18487 | |
Insulfrog3
13 posts |
When I traveled around London on the 'National Rail' network, I noticed that some of the points, crossings and slips have got the rails coloured white. Why is that?
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| Re: White points and crossings? 27/07/2011 at 21:41 #18488 | |
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Sam Tugwell
493 posts |
This is the same on the point to enter Platform 1 in the Down direction at Newton Abbot. Been wondering what it is myself 
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| Re: White points and crossings? 27/07/2011 at 21:43 #18489 | |
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UKTrainMan
1803 posts |
At a bit of a guess, could it be a sign that they may need or are due for replacement soon? I recall at Windsor & Eton Riverside after Thumper 1001 derailed whilst pulling into the station on a tour a while back now the RAIB guy I had a quick word with there pointed out the obvious, such as the white crosses on the wooden sleepers....could potentially be the same with points? Not sure though.
Any views and / or opinions expressed by myself are from me personally and do not represent those of any company I either work for or am a consultant for. Log in to reply |
| Re: White points and crossings? 27/07/2011 at 21:57 #18492 | |
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Sacro
1171 posts |
I've heard a few different reasons, one is to make them stand out, another is to reflect heat from them.
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| Re: White points and crossings? 27/07/2011 at 22:07 #18495 | |
headshot119
4869 posts |
Designed to reflect heat apparently, isn't just points some stretches of plain line are also done in white.
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| Re: White points and crossings? 27/07/2011 at 22:27 #18497 | |
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UKTrainMan
1803 posts |
Ahhh but of-course...'anti-heat'!!! To think I was just talking about white and heat deflection only just earlier when shown a photo of a black-coloured locomotive and for some reason I remembered the AnsaldoBreda V250 train with it's white front and the heat differences inside each due to the outside colour.
Any views and / or opinions expressed by myself are from me personally and do not represent those of any company I either work for or am a consultant for. Last edited: 27/07/2011 at 22:27 by UKTrainMan Log in to reply |
| Re: White points and crossings? 27/07/2011 at 23:30 #18503 | |
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officer dibble
390 posts |
Headshot wins! We have them at Reading too. Its put on sets of points that are used regularly to keep them working as long as possible in times of extreme hot weather. Log in to reply |
| Re: White points and crossings? 28/07/2011 at 10:19 #18510 | |
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Sam Tugwell
493 posts |
Isnt that because the rail will buckle? Thats what happened at the South Devon Railway at Totnes when the rail buckled and the service couldnt run between Staverton and Totnes.
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| Re: White points and crossings? 28/07/2011 at 10:59 #18518 | |
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ralphjwchadkirk
275 posts |
Heat causes metal to expand. Rails are placed with a small gap between them to account for this (~3mm), but sometimes the expansion is too much, and the stress on the rail causes it to buckle, usually sideways. Points are painted white to stop the small expansion knocking the detection out. Plain line is for the above reason. Last edited: 28/07/2011 at 10:59 by ralphjwchadkirk Log in to reply The following user said thank you: Sam Tugwell |
| Re: White points and crossings? 28/07/2011 at 11:00 #18519 | |
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Sam Tugwell
493 posts |
I thought it was something like that. Thanks Ralph! 
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| Re: White points and crossings? 28/07/2011 at 11:19 #18520 | |
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Sacro
1171 posts |
" said:Headshot wins!Get your glasses checked! I posted that one first! 
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| Re: White points and crossings? 28/07/2011 at 13:36 #18524 | |
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officer dibble
390 posts |
" said:" said:So you did, glasses duly cleaned!Headshot wins!Get your glasses checked! I posted that one first! :( 
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| Re: White points and crossings? 28/07/2011 at 13:46 #18525 | |
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AndyG
1835 posts |
Paul must have had his 'Reading' glasses on. :whistle:
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| Re: White points and crossings? 31/07/2011 at 10:12 #18771 | |
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Jan
890 posts |
" said:Heat causes metal to expand. Rails are placed with a small gap between them to account for this (~3mm), but sometimes the expansion is too much, and the stress on the rail causes it to buckle, usually sideways.Not if you've got Continuously Welded Rail. There, the rails are welded together at a neutral temperature roughly halfway between the coldest temperatures in winter, and the hottest ones in summer. Any stress caused by the rails trying to expand in summer is supposed to be taken by the sleepers and the ballast, if that fails, then you'll obviously get buckles. Likewise, in extremely cold weather, the rail might break. Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Log in to reply |
| Re: White points and crossings? 31/07/2011 at 10:35 #18776 | |
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Backup
89 posts |
A reasonable enough official reason; but could there be secondary benefits? I'm thinking in terms of enhanced contrast: Perhaps white rail against dark grey ballast, versus conventional grey rail against dark grey ballast; makes it easier to observe the correct points configuration if passing & examining? (Note: I don't know real-world procedure that well; so apologies if I'm talking rubbish - just venturing a thought.) Log in to reply |
| Re: White points and crossings? 31/07/2011 at 10:41 #18781 | |
Peter Bennet
5362 posts |
Bit of useless information. From recollection of a walk across the bridge I did with the Dundee University Transport club back in 1983-ish the Forth Rail Bridge has something like 6 feet of expansion allowance. Peter I identify as half man half biscuit - crumbs! Log in to reply |
| Re: White points and crossings? 31/07/2011 at 12:48 #18804 | |
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Jan
890 posts |
Seems to figure, a rough calculation with a temperature differential of 60°K, α = 12*10[sup]−6[/sup] for Steel and a length of 2,528.7 m according to Wikipedia gives about 1.82 metres (or 6 feet) length differential. I guess something like this will be used there. Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Last edited: 31/07/2011 at 15:13 by Jan Log in to reply |
