Disruption between Castle Cary to Newbury (31/05): Anyone know why?

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Chris Butler

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Yesterday for most of the day trains were running slow from Castle Cary to Newbury. See below.


Anyone know why ? On the 16:41 Plymouth to Paddington it was announced as a 60mph limit due to heat. Was yesterday really hot enough to cause rail expansion problems?
 
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zwk500

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Could well have been - remember the rail will heat up much, much quicker than the surrounding air temperature if it's in direct sunlight all day. Add in any of the myriad of local factors that could affect it and then the risk of buckling is high enough for a restriction.

Heat-related restrictions are the delay reason given on TRUST for the sections around Pewsey.
 

Chris Butler

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Could well have been - remember the rail will heat up much, much quicker than the surrounding air temperature if it's in direct sunlight all day. Add in any of the myriad of local factors that could affect it and then the risk of buckling is high enough for a restriction.

Heat-related restrictions are the delay reason given on TRUST for the sections around Pewsey.

Thanks for the TRUST confirmation.

Sure the rail is heated by the sun's radiation (sunlight), but, by the same token, the lower air temperature means the air will be cooling the rails.

If I understand it well, the ideal conditions for buckling are:-
  1. Direct sunlight all day (no clouds)
  2. Sun overhead (nearer the summer solstice).
  3. End of a warm spell (air temperature higher, so less cooling).
  4. Summer. Ground has fully warmed (so less cooling and more re-radiation of the sunlight).
  5. Dry soil - no water to form a 'heat bath' and no evaporative cooling.
Yesterday, we only had 1), which is why I'm surprised that there was an expansion problem.
 

zwk500

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Thanks for the TRUST confirmation.

Sure the rail is heated by the sun's radiation (sunlight), but, by the same token, the lower air temperature means the air will be cooling the rails.

If I understand it well, the ideal conditions for buckling are:-
  1. Direct sunlight all day (no clouds)
  2. Sun overhead (nearer the summer solstice).
  3. End of a warm spell (air temperature higher, so less cooling).
  4. Summer. Ground has fully warmed (so less cooling and more re-radiation of the sunlight).
  5. Dry soil - no water to form a 'heat bath' and no evaporative cooling.
Yesterday, we only had 1), which is why I'm surprised that there was an expansion problem.
You've also got to consider the local factors, such as curvature, ballast depth, rail type, proximity to an expansion joint, pre-stressing, expected traffic...

NR doesn't put a 20mph ESR on lightly. The people who assess and authorise them have quite a lot of experience in doing so. I am not one of those people, so can't comment why that particular location got a restriction but others didn't.
 

YorkshireBear

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You've also got to consider the local factors, such as curvature, ballast depth, rail type, proximity to an expansion joint, pre-stressing, expected traffic...

NR doesn't put a 20mph ESR on lightly. The people who assess and authorise them have quite a lot of experience in doing so. I am not one of those people, so can't comment why that particular location got a restriction but others didn't.
Agreed and as there was not widespread heat disruption yesterday if say local track factors are more prevalent here.
 

Wilts Wanderer

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It could well be that NR are behind with their re-stressing programme ahead of this summer. If the rails are still stressed for winter temperatures (i.e assumes contraction due to freezing) then a sudden hot spell with temperatures in the mid-20s creates just as high risk of track buckles as a hot midsummer when the rails are stressed for high temperatures.

(Does the ban on red-zone working hamper the stressing programme I wonder?)
 

zwk500

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(Does the ban on red-zone working hamper the stressing programme I wonder?)
AIUI it's not an outright ban, but more a general presumption against. Either way, it will have been factored into the plan (given engineering is agreed years in advance) so a regular programme is far more likely to have been disrupted by emergency diversion of resources in response to incidents or COVID practices than by a restriction on Red Zone working.
 

mcmad

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It could well be that NR are behind with their re-stressing programme ahead of this summer. If the rails are still stressed for winter temperatures (i.e assumes contraction due to freezing) then a sudden hot spell with temperatures in the mid-20s creates just as high risk of track buckles as a hot midsummer when the rails are stressed for high temperatures.

(Does the ban on red-zone working hamper the stressing programme I wonder?)
there is no difference in the stressing between summer and winter, its always 21-27°C. The speed will have most likely been imposed due to recent works disturbing the consolidated ballast as others have already said.
 

Bald Rick

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Thanks for the TRUST confirmation.

Sure the rail is heated by the sun's radiation (sunlight), but, by the same token, the lower air temperature means the air will be cooling the rails.

If I understand it well, the ideal conditions for buckling are:-
  1. Direct sunlight all day (no clouds)
  2. Sun overhead (nearer the summer solstice).
  3. End of a warm spell (air temperature higher, so less cooling).
  4. Summer. Ground has fully warmed (so less cooling and more re-radiation of the sunlight).
  5. Dry soil - no water to form a 'heat bath' and no evaporative cooling.
Yesterday, we only had 1), which is why I'm surprised that there was an expansion problem.

There’s heat speeds coming on in various places.

With the sun at almost maximum ‘height’ at this time of year, the solar gain is significant. If there was trackwork in the area recently, and the rail had not been stressed or the ballast disturbed, then it’s quite easy to get a Critical Rail temperature of around 40-45C, which is what I imagine rail temps were yesterday.
 

70014IronDuke

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How does, say, France manage to cope? I remember bombing along between Paris Austerlitz - Bordeaux at 200 kmph under blazing hot July sun - 10 - 15 days after mid summer - way back in the 70s. The air temperature was surely around 40C, so goodness knows, the rails must have been near glowing orange (joke - but you know what I mean).
 

Bald Rick

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How does, say, France manage to cope? I remember bombing along between Paris Austerlitz - Bordeaux at 200 kmph under blazing hot July sun - 10 - 15 days after mid summer - way back in the 70s. The air temperature was surely around 40C, so goodness knows, the rails must have been near glowing orange (joke - but you know what I mean).

Exactly the same as we do, because the laws of physics apply in France too. A couple of summers ago on a very hot day SNCF imposed restrictions on almost the whole Paris suburban network, and much of the LGV network, which caused chaos, as you can imagine.

You’ll notice that there are plenty of trains running at 125mph in the U.K. today. And some at higher speeds. Speed restrictions are only applied where the combination of the rail stress free temperature and local track ‘fixity’ requires it. 99% + of the track is fine.

Edit: see my post on a thread from a couple of years ago:

 
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geoffk

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I noticed recently that the rails at Newton St. Cyres on the Barnstaple line were painted white and have seen similar treatment in Italy. I read that this can reduce the temperature of the rails by 5 to 10 deg C.
 
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zwk500

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I noticed recently that the rails at Newton St. Cyres on the Barnstaple line were painted white and have seen similar treatment in Italy. I read that this can reduce the temperature of the rails by 50 to 10deg C.
Yep, fairly common for point ends and crossings to be painted white across the country for expansion issues. Hadn't noticed much plain rail but I'm not surprised.
 

zwk500

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I thought that it was just to signify a trip risk.
Not the trip risk, as that's mitigated by appropriate training and briefing, as well as agreed walking routes with suitable track crossings.

  • We paint certain parts of the rail white so they absorb less heat – and expand less. Typically, a rail painted white is 5°C to 10°C cooler.
 

brad465

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I travelled back from Castle Cary yesterday (and out to it on Friday), and remember there being a 20mph speed restriction east of CLC on the down line, and passing the east side of the station a similar restriction was visible from the road on the up line. My outbound train was also late, but that had more to do with two Mendip freight quarry trains being in the way until we passed one at Woodborough (for Whatley) and the other at Fairwood jct (sitting on the avoiding line while my train left Westbury itself).

However coming back yesterday there were other restrictions just west of the Woodborough loops, around Hungerford-Kintbury, and even on the GWML over a crossover (affecting all 4 tracks regardless of what movement a train was doing), between Twyford and Maidenhead.

The conductor did say heat-related speed restrictions were responsible (about 25 minutes late by Paddington), although my train (18:39 from CLC, 16:50 from Plymouth), was also late out of Laira and had a 10 minute departure delay at the start. After that it was a simple matter of "lateness causes lateness", not helped by being stuck behind a stopper between Newton Abbott and Dawlish Warren as a consequence.
 

ChrisHogan

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I travelled back from Castle Cary yesterday (and out to it on Friday), and remember there being a 20mph speed restriction east of CLC on the down line, and passing the east side of the station a similar restriction was visible from the road on the up line. My outbound train was also late, but that had more to do with two Mendip freight quarry trains being in the way until we passed one at Woodborough (for Whatley) and the other at Fairwood jct (sitting on the avoiding line while my train left Westbury itself).

However coming back yesterday there were other restrictions just west of the Woodborough loops, around Hungerford-Kintbury, and even on the GWML over a crossover (affecting all 4 tracks regardless of what movement a train was doing), between Twyford and Maidenhead.

The conductor did say heat-related speed restrictions were responsible (about 25 minutes late by Paddington), although my train (18:39 from CLC, 16:50 from Plymouth), was also late out of Laira and had a 10 minute departure delay at the start. After that it was a simple matter of "lateness causes lateness", not helped by being stuck behind a stopper between Newton Abbott and Dawlish Warren as a consequence.
A pretty dire today all over the Great Western network. 1A73 0505 Penzance sat down between West Drayton and Stockley this morning - eventually set back to West Drayton to detrain passengers and then crawled to Paddn on the Up Main getting there about 1230. Resulted in two more cancellations. Various track-circuit or point failures at Southall, Hayes & H and in the Didcot area this afternoon. The problem at Hayes saw down locals diverted to run through platform 4 during the evening peak.
 

irish_rail

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There has been a 60mph restriction all afternoon on the b and h all the way from Somerton tunnel to Heywood Rd junction at Westbury for past few days.
On top of this there are numerous other restrictions, many of 20mph dotted between Somerton and Reading. Its the worst I've ever seen it in terms of TSRs.
A 20mph TSR on the up main at Ruscombe near Twyford is compounding the delays further!
 

embers25

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We used the 0646 yesterday from Exeter when it was cold and misty and apart from the 20mph limits at Castle Cary and Twyford we went slow a lot of the way and also went via Westbury despite being non-stop which added 5+ mins as it was a much slower than usual crawl through Westbury despite no trains being in front. On the way back things were much better but still ran late.
 

brad465

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There has been a 60mph restriction all afternoon on the b and h all the way from Somerton tunnel to Heywood Rd junction at Westbury for past few days.
On top of this there are numerous other restrictions, many of 20mph dotted between Somerton and Reading. Its the worst I've ever seen it in terms of TSRs.
A 20mph TSR on the up main at Ruscombe near Twyford is compounding the delays further!
The former speed restriction of 60mph must be new, or at least wasn't in place yesterday when I travelled along the line and/or saw trains travelling at speeds that looked >60mph. The 20mph ones though you mention were definitely present, including that Twyford one which I suspect is the most disruptive single one based on number of trains affected.
 

VP185

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We used the 0646 yesterday from Exeter when it was cold and misty and apart from the 20mph limits at Castle Cary and Twyford we went slow a lot of the way and also went via Westbury despite being non-stop which added 5+ mins as it was a much slower than usual crawl through Westbury despite no trains being in front. On the way back things were much better but still ran late.

The Westbury avoiding line has been closed due to a points failure for nearly a week.
 

irish_rail

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The former speed restriction of 60mph must be new, or at least wasn't in place yesterday when I travelled along the line and/or saw trains travelling at speeds that looked >60mph. The 20mph ones though you mention were definitely present, including that Twyford one which I suspect is the most disruptive single one based on number of trains affected.
The 60mph was from 1230 to 1730.
 

brad465

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The Westbury avoiding line has been closed due to a points failure for nearly a week.
Was that in only one direction? I remember a freight train bound for Merehead Quarry waiting on the down avoiding line on Friday afternoon while the train I was on went ahead after calling at Westbury.
 

Horizon22

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The speed restrictions on the B&H are variant and primarily kick in after the rail temp gets high rboivh which, as @irish_rail suggests, are generally the middle of the day after the watchman at various points makes the readings.

W.Country trains generally get about 40-50 minutes at either end and are generally self-contained 802 diagrams so the return working will leave the origin only slightly late or on timeonly to hit the same problem again.
 

jdxn

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AIUI it's not an outright ban, but more a general presumption against. Either way, it will have been factored into the plan (given engineering is agreed years in advance) so a regular programme is far more likely to have been disrupted by emergency diversion of resources in response to incidents or COVID practices than by a restriction on Red Zone working.
On Western it is an outright ban. There is zero red zone working. However this won’t be a factor with this.
 
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There still seems to be issues, as almost every train today between Exeter and Reading in both directions has been delayed, often by over 20 minutes. The strange part is that a small number of services seem completely unaffected. Does anyone know what is happening?
 
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