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Author Topic: Hot Rails  (Read 607 times)
grahame
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« on: May 08, 2018, 06:05:53 am »

This is not something I was aware of in my youff.  Has it always been a problem - just one we didn't hear about?

Quote
Alterations to services between Reading and London Paddington
Due to a speed restriction because of high track temperatures between Reading and London Paddington trains have to run at reduced speed on some lines towards London Paddington.
Train services running to and from these stations may be delayed or revised. Disruption is expected until the end of the day.
Further Information
A speed restriction has been imposed in the Slough area on the Main Line towards London Paddington following the high temperature recorded in the rails at that location yesterday. This is the line which is traversed by the fast / semi fast services between Reading and London Paddington. As a result fewer trains will be able to operate over that section of line and certain services which would normally call at Slough will have that stop withdrawn.
Last Updated:08/05/2018 04:02
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ellendune
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« Reply #1 on: May 08, 2018, 07:00:32 am »

This was raised a few days ago on another thread http://www.firstgreatwestern.info/coffeeshop/index.php?topic=14689.msg236122#msg236122 with a response
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NickB
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« Reply #2 on: May 08, 2018, 07:05:08 am »

Bit early in the day for such concerns isn’t it?  If track temperatures are causing problems at 7am what will happen by midday?
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TaplowGreen
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« Reply #3 on: May 08, 2018, 07:10:48 am »

Bit early in the day for such concerns isn’t it?  If track temperatures are causing problems at 7am what will happen by midday?

It's 14 degrees at the moment........phew what a scorcher!
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« Reply #4 on: May 08, 2018, 07:29:30 am »

It is very likely that as a result of all the track work over the weekend sections may not be stressed, fully ballasted and tamped .  Rail stressing is where the rails are tensioned for a nominal 20 deg C also the ballast has to be compacted and tamped, there are machines that do compacting but I believe this does not allow for 125 running.

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« Reply #5 on: May 08, 2018, 07:38:15 am »

I passed the affected area on 1K71 just now. We reduced speed to around 20mph or so I'd say for a couple of miles and then back up to line speed so not too bad.
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broadgage
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« Reply #6 on: May 08, 2018, 08:23:24 am »

Bit early in the day for such concerns isn’t it?  If track temperatures are causing problems at 7am what will happen by midday?

It's 14 degrees at the moment........phew what a scorcher!

At this rate, cancellations due to snow or ice will soon coincide with cancellations due to high rail temperatures !

IIRC, snow and ice cancellations have happened at temperatures as high as 4 degrees, and now we have cancellations due to high rail temperatures at 14 degrees. So only an 8 degree range for normal operation, from 5 degrees to 13 degrees.
So how long until say 8 degrees gives snow and ice problems AND high rail temperature problems.

I have previously commented that we increasingly have a "fair weather only railway" this seems to be worsening with a narrowing range of temperatures for normal operation.
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a-driver
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« Reply #7 on: May 08, 2018, 08:52:53 am »

If the speed restriction in question is between Maidenhead and Slough then, what was a 50mph temporary speed restriction following track renewal is now a 20mph emergency speed restriction. This could be a result of engineering works not being fully completed overnight or an inspection could have picked up a defect which could even be as a result of yesterday’s high track temperatures.
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stuving
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« Reply #8 on: May 08, 2018, 09:14:59 am »

This is not something I was aware of in my youff.  Has it always been a problem - just one we didn't hear about?

Quote
Alterations to services between Reading and London Paddington
Due to a speed restriction because of high track temperatures between Reading and London Paddington trains have to run at reduced speed on some lines towards London Paddington.
Train services running to and from these stations may be delayed or revised. Disruption is expected until the end of the day.
Further Information
A speed restriction has been imposed in the Slough area on the Main Line towards London Paddington following the high temperature recorded in the rails at that location yesterday. This is the line which is traversed by the fast / semi fast services between Reading and London Paddington. As a result fewer trains will be able to operate over that section of line and certain services which would normally call at Slough will have that stop withdrawn.
Last Updated:08/05/2018 04:02

Since the restriction was announced at 4 am, I presume it was based an a PW inspection that found something not right with the track from yesterday - e.g. something was pushed slightly out of line and didn't just pull back into place, or which might be made worse by full-speed running.

The high stress is of course the result of the track being continuous (welded). However, I would guess that at temperature extremes jointed track might run out of travel at its fishplate joints if these and the track were installed wrongly, or had moved or seized. If the gaps got full of something while open, that would get squashed as the heat closed them - though a single 60' length doesn't need much of a gap (about 5 mm for 20 K).
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a-driver
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« Reply #9 on: May 08, 2018, 10:15:53 am »

Taken from the GWR website.


“Speed Restrictions in the Slough area

Following high temperatures seen over the Bank Holiday Weekend, Network Rail has put in place
a temporary speed limit for Tuesday morning over a new section of track installed over the weekend. This is a safety precaution to allow the new track to settle and adjust, to the high speeds of a full train service.

This is a temporary measure and will be removed as soon as it is safe to do so.”
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grahame
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« Reply #10 on: May 08, 2018, 10:46:06 am »

Taken from the GWR website.


“Speed Restrictions in the Slough area

Following high temperatures seen over the Bank Holiday Weekend, Network Rail has put in place
a temporary speed limit for Tuesday morning over a new section of track installed over the weekend. This is a safety precaution to allow the new track to settle and adjust, to the high speeds of a full train service.

This is a temporary measure and will be removed as soon as it is safe to do so.”


I recall it being utterly standard practise for newly replaced tracks to be bedded in with an initial speed restriction, but (now that I thick about it) I've not come across that recently.  Perhaps this is just the older standard being applied with the higher temperatures being something of a red herring - or perhaps making for problems yesterday so the tracks haven't yet been fully stressed?   Fair enough - if that's the case, initial report was a bit confusing as it suggested today's temperatures caused the problem.
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Louis94
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« Reply #11 on: May 08, 2018, 11:17:41 am »

I recall it being utterly standard practise for newly replaced tracks to be bedded in with an initial speed restriction, but (now that I thick about it) I've not come across that recently.  Perhaps this is just the older standard being applied with the higher temperatures being something of a red herring - or perhaps making for problems yesterday so the tracks haven't yet been fully stressed?   Fair enough - if that's the case, initial report was a bit confusing as it suggested today's temperatures caused the problem.

This is a planned TSR following track renewals over the weekend. 50mph in both directions between 19m4ch and 19m35ch, on the main lines.

Update: Just done some digging, turns out the speed has actually been reduced to 20mph ESR.
« Last Edit: May 08, 2018, 11:25:58 am by Louis94 » Logged
paul7755
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« Reply #12 on: May 08, 2018, 01:01:03 pm »

I recall it being utterly standard practise for newly replaced tracks to be bedded in with an initial speed restriction, but (now that I thick about it) I've not come across that recently.  Perhaps this is just the older standard being applied with the higher temperatures being something of a red herring - or perhaps making for problems yesterday so the tracks haven't yet been fully stressed?   Fair enough - if that's the case, initial report was a bit confusing as it suggested today's temperatures caused the problem.
Line speed handback of possessions is the modern aim.  Immediately after the usual tamping process they use a device known as a dynamic track stabiliser (DTS) which effectively provides the initial running in period in a short time.

Found a Rail News article about it here:  https://www.railnews.co.uk/news/2017/02/15-network-rail-on-track-to.html

It could be that the high temperatures on the day delayed the rail stressing and they ran out of time for the DTS to run.  Better to hand back with a TSR.

Paul
   
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« Reply #13 on: May 08, 2018, 06:11:39 pm »

I recall it being utterly standard practise for newly replaced tracks to be bedded in with an initial speed restriction, but (now that I thick about it) I've not come across that recently.  Perhaps this is just the older standard being applied with the higher temperatures being something of a red herring - or perhaps making for problems yesterday so the tracks haven't yet been fully stressed?   Fair enough - if that's the case, initial report was a bit confusing as it suggested today's temperatures caused the problem.

This is a planned TSR following track renewals over the weekend. 50mph in both directions between 19m4ch and 19m35ch, on the main lines.

Update: Just done some digging, turns out the speed has actually been reduced to 20mph ESR.

The Project Manager and Project Engineer would have booked the TSR into the timetable (there is allowance built in the WTT for engineering speed restrictions) they would also have made arrangements for track inspections (this required by NR standards) and would have had the ESR boards available, this is normal practice for any track relaying especially if it involved a "deep dig" or UTX (under track crossing) for cables, pipes etc.
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ellendune
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« Reply #14 on: May 08, 2018, 09:47:26 pm »

Line speed handback of possessions is the modern aim.  Immediately after the usual tamping process they use a device known as a dynamic track stabiliser (DTS) which effectively provides the initial running in period in a short time.

Found a Rail News article about it here:  https://www.railnews.co.uk/news/2017/02/15-network-rail-on-track-to.html

It could be that the high temperatures on the day delayed the rail stressing and they ran out of time for the DTS to run.  Better to hand back with a TSR.

Paul
   

That article makes it sound like its new technology.  I worked on the development as a student at RTC Derby in 1977.  It was first used in anger on the Crewe remodelling which was the first big blockade renewal in modern times - 1985. 
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