Speed Restrictions due to Heat

[Trog]

There is a lot more continuously welded rail these days than there was 15-20 years ago.

In hot weather jointed and CWR are more or less the same thing. Just consider the natural temperature of the CWR as being equal to the joint closure temperature of the jointed.

The big difference is that jointed track tends to be older, and on minor lines where the level of maintenance is lower. Other factors such as curvature, wider sleeper spacing, timber sleepers, that also reduce the temperature the track can stand are also more often found in jointed track.

 

[tsr]

I don't think watering third rails is a good strategy...

It does rain in third rail land, y'know...

 

[rebmcr]

I don't think watering third rails is a good strategy...

Do they turn them off when it rains, then? Nope.

 

[The Informer]

It's not just the rails that are the issue. The main reasons for heat related speeds are ballast disturbances, such as tamping, lifting and packing, track renewals etc.
For CWR the issues can be under stressed track or ballast shortage.
For Jointed track it can be the the gaps at the rail ends are incorrectly set. Rail gaps are adjusted as required before the on-set of hot weather.
All of these things give the track a lower critical rail temperature and within each CRT there will be a watch temperature (W), a 30/60 temperature, at which a speed restriction of 30/60 will be imposed and a 20 temperature, which means when a certain temperature is reached a 20 will be imposed. For ballast shortage there is no 30/60, after the watch temperature the next trigger is the 20. Depending on location a 20 may need to be imposed at the watch temperature, this is if the track cannot be inspected safely by staff at locations with curves etc with limited sighting of trains. There is a lot more to it than rails getting hot.

In a nutshell this is spot on!!! Well done!!!

 

[broadgage]

Perhaps one of the advantages of putting trains in tunnels, keeps the temperature conditions far more stable.

More crossrail esque services!

I read somwhere, that rails in tunels are sometimes made of a special grade of steel that is harder wearing. This has the advantage of extending the interval between rail replacements, which tend to be particulary expensive and disruptive in tunnels.
Unfortunatly this special hard wearing type of rail can not be used more widely because it has a higher coefficient of thermal expansion than standard rail. If used in significant lengths out in the open, then the expansion could be dangerous.
Fine in most longish tunnels though since the temperature varies less than out in the open.

AFAIK the same harder wearing steel is sometimes used for points and crossings since the greater expansion is of less consequence over these relatively small features, as compared to miles of plain track.

 

[michael769]

Network Rail in Scotland are using IR reflective paint and, yes really, water sprinkler systems in an effort to keep the network functioning.

https://twitter.com/networkrailscot/status/355339364957552645

It certainly worked today with no heat related disruption or speed limits. The big test will be tomorrow with some Eastern areas predicted to experience the hottest day for almost 20 years.

On the subject of extraordinary measures I wonder if they have every considered using those temporary construction barriers/screens for shading at problem locations. I know there will be no space in some places, but there must be plenty of places, especially on non electrified lines where it would work. You only really need to shade things during the hottest part of the day.
--- old post above --- --- new post below ---
Sprinkers in action at Haymarket East

http://twitpic.com/d27cry

 

[Monty]

A simple yet effective solution, but what's happens when there is a hosepipe ban?

 

[Boodiggy]

In a nutshell this is spot on!!! Well done!!!

I hope so, it's how i earn my living

 

[michael769]

A simple yet effective solution, but what's happens when there is a hosepipe ban?

"Hosepipe bans" only apply to washing cars andwatering gardens. In any event they could use grey water.

The approach seems to have been a success. Despite tempratures exceeding Tuesdays, there was no heat related disruption.

 

[rebmcr]

A simple yet effective solution, but what's happens when there is a hosepipe ban?

They only really happen down south. In Manchester, I can only remember one in the last 20 years. The hills are literally riddled with lakes and reservoirs and there's a significant drop in the population using it up.

 

[Eagle]

Despite tempratures exceeding Tuesdays, there was no heat related disruption.

Apart from the problems at Swindon, which were caused by a large and concentrated area of heat localized to several signalling cables.
--- old post above --- --- new post below ---

They only really happen down south. In Manchester, I can only remember one in the last 20 years. The hills are literally riddled with lakes and reservoirs and there's a significant drop in the population using it up.

The west of the country (facing into the prevailing wind) is quite a lot wetter than the east. It's more noticeable in the north where there are the Pennines in the way, stopping a lot of rain getting to Yorkshire and the north east.

 

[infobleep]

I'm sure their is a logical reason for this and it may have been answered in another thread but why, except for the day when their was a track defect, has there not been a reduction in the number of trains leaving Waterloo.

The met office have issued weather warnings this week but I didn't hear about any being issued when the speed restrictions and less trains were running on that Monday.

There still has been speed restrictions elsewhere on the SWT network so what has changed at Waterloo?

Clearly network rail / SWT are not going to introduce restrictions for the hell of it. It's costs them money to do so. Which means there must be a reason for not having to implement it.

 

[SussexSpotter]

MPVs?.....

 

[carriageline]

There's no paths for MPVs unfortunately, at least from what I have reas

 

[SussexSpotter]

Trains have sandboxes to help grip the rails when it is wet and slippery, so would coolantboxes be something to consider????.....

 

[transmanche]

Trains have sandboxes to help grip the rails when it is wet and slippery, so would coolantboxes be something to consider????.....

I think the 'sprinkler' that michael769 mentioned in post #96 would probably be simpler and more effective. (The video he linked to shows it in operation and says it reduced the rail temp by 4C in 10 mins.)

 

[michael769]

In this heat any water sprayed on the rails will evaporate in seconds. So spray from passing trains is unliely to have in impact. A continuous spray isxwhat is needed.

As to using the stuff in car radiators? That is just water and anti-freeze. Why would you want to prevent feezing in this weather?

 

[evoluzione]

A garden lawn sprinkler popped up just outside Man Vic last week, quite amusing as your coming up to it as it spins rounds watering a set points in the 4 foot.

 

[trainmananthon]

Wouldn't like to be travelling down south next week. Temperatures supposed to increase to 35 degrees with massive flash floods and extreme thunderstorms. Network rail and commuters won't have a very good time

 

[Darren R]

Wouldn't like to be travelling down south next week. Temperatures supposed to increase to 35 degrees with massive flash floods and extreme thunderstorms. Network rail and commuters won't have a very good time

Not been reading the Daily Express have we! That is a slightly alarmist version of the weather forecast for next week!

 

[trainmananthon]

Not been reading the Daily Express have we! That is a slightly alarmist version of the weather forecast for next week!

Nope. I don't read anything like this. I just been looking at the weather and watching the online forecasts

 

[Monty]

A somewhat cooler day today, but the forecast does indeed indicate a return to 30+ degrees with the potential for thunderstorms. Not that I want to sound ungrateful for all this warm weather but I would like the temperature to be a tad lower than last week, working those 455s has been murder!

 

[507 001]

A garden lawn sprinkler popped up just outside Man Vic last week, quite amusing as your coming up to it as it spins rounds watering a set points in the 4 foot.

There's 2 of them now! And metrolink have stolen the idea too, one of the points at bury had a sprinkler, although I can't quite figure out why as it seems like it would be in the shade for most of the day!

 

[Darren R]

Originally Posted by Darren R
Not been reading the Daily Express have we! That is a slightly alarmist version of the weather forecast for next week!

Nope. I don't read anything like this. I just been looking at the weather and watching the online forecasts

Trainmananthon I take it back and apologise profusely - it seems your weather forecast for this week wasn't anywhere near so alarmist as I first thought!

Judging by the MetOffice website Nottingham is currently in the throes of a very nasty thunderstorm with absolutely torrential rain. Hope it doesn't impact on the engineering work there.

By the way, I was only joking with my merry little Express quip: I would never say such a thing seriously (there are laws about defamation of character, after all! )