Speed Restrictions due to heat!! 14c

[Y Ddraig Coch]

I didn't see this posted anywhere else, Earlier today from our local paper about 20mph speed restrictions due to track being too hot at 14c......

http://www.dailypost.co.uk/news/north-wales-news/north-wales-trains-delayed-tracks-12747123

"passengers have been warned to expect delays on trains between Prestatyn and Flint because the tracks are too hot.

Arriva Trains Wales are running at a reduced speed on the line towards Chester because of the heat.


The Arriva journey check website says Network Rail have reported that "track monitoring equipment has indicated high rail temperatures between Talacre and Mostyn".

This means an emergency speed limit of 20mph has been imposed for approximately one mile between Prestatyn and Flint.


According to the Met Office, the temperature at Talacre is currently 14 degrees.

Trains are currently delayed for up to 20 minutes.

Disruption is expected until 5.30pm."

 

[Welshman]

I didn't see this posted anywhere else, Earlier today from our local paper about 20mph speed restrictions due to track being too hot at 14c......

http://www.dailypost.co.uk/news/north-wales-news/north-wales-trains-delayed-tracks-12747123


"passengers have been warned to expect delays on trains between Prestatyn and Flint because the tracks are too hot.

Arriva Trains Wales are running at a reduced speed on the line towards Chester because of the heat.


The Arriva journey check website says Network Rail have reported that "track monitoring equipment has indicated high rail temperatures between Talacre and Mostyn".

This means an emergency speed limit of 20mph has been imposed for approximately one mile between Prestatyn and Flint.


According to the Met Office, the temperature at Talacre is currently 14 degrees.

Trains are currently delayed for up to 20 minutes.

Disruption is expected until 5.30pm."

This has actually been reported by Philipe in the Journey Check Reasons thread elsewhere, but here might be a better place to speculate as to why this alarm was given, for, as you say, the temperature reached only 14° and it's odd there wasn't a similar problem on the down line!

I wonder if the affected stretch was one of those recently re-laid, and if it could have been anything to do with that - newish equipment experiencing teething-problems perhaps?

Only speculating........

 

[TheEdge]

Speculation. Its worth noting the rails can often be hotter than the air temperature so if they've been in direct sunlight they will be warm.

Welshman has already mentioned newly laid track, it may not have been completely settled yet and have lower tolerance to heat.

 

[tiptoptaff]

Track was recently relaid, over the weekend in fact, and due to the ongoing works in the area is yet to be bedded in and fully stressed. As such, more vulnerable to unseasonably warm weather. Estimated track temp was well over double the air temp

 

[edwin_m]

Track was recently relaid, over the weekend in fact, and due to the ongoing works in the area is yet to be bedded in and fully stressed. As such, more vulnerable to unseasonably warm weather. Estimated track temp was well over double the air temp

Would have been better to give the reason for delay as speed restriction due to recent track work.

 

[The Lad]

Any CWR that has been recently disturbed is more vulnerable to buckling due to heat, hence not a lot of ramping in hot weather. Rail tends to absorb the suns heat especially on E/W lines. Also a reason for whitewashing the rails to reflect some of the heat.

 

[Bald Rick]

I posted a detailed explanation on heat speed restrictions a couple of years ago, but I'm not good enough at the search function to find it. In short, almost all track related heat speed restrictions are due to continuously welded rail not having been stressed. The restriction is imposed above a specific rail temperature, which is a function of several factors including:

The rail temperature when it was installed
Curvature
Sleeper spacing
Ballast provision
Amount of traffic that has passed over since installation.

Rail temperature itself is basically ambient + up to 20C, depending on the weather, time of year and time of day. Early afternoon on a cloudless day in May, June or July being the highest increase, but a sunny day in March will still be quite a lift.

If all these factors go against you, it is entirely possible to have a heat speed restriction when it is actually 0C ambient. I certainly had one at 7C once.

 

[Deepgreen]

Whether actually heat-related or not, from the point of view of passengers' credulity - 'recent track works' might have been a better explanation.

 

[jon0844]

Whether actually heat-related or not, from the point of view of passengers' credulity - 'recent track works' might have been a better explanation.

Definitely. Without the ability for many people to get a proper explanation, they'll just laugh and think it's madness - and 'typical'. It then furthers their existing prejudice that does more long-term harm.

 

[Welshman]

I posted a detailed explanation on heat speed restrictions a couple of years ago, but I'm not good enough at the search function to find it. In short, almost all track related heat speed restrictions are due to continuously welded rail not having been stressed. The restriction is imposed above a specific rail temperature, which is a function of several factors including:

The rail temperature when it was installed
Curvature
Sleeper spacing
Ballast provision
Amount of traffic that has passed over since installation.

Rail temperature itself is basically ambient + up to 20C, depending on the weather, time of year and time of day. Early afternoon on a cloudless day in May, June or July being the highest increase, but a sunny day in March will still be quite a lift.

If all these factors go against you, it is entirely possible to have a heat speed restriction when it is actually 0C ambient. I certainly had one at 7C once.

Thank you for that full explanation.