Heated Rails?

[TorqueOfTheDevil]

Forgive a stupid question from a layman, but...

In the current cold snap, how come rails aren't heated to prevent ice forming on them?

It would seem that a small element running along the rail could be used, during cold weather, to keep the rail temperature just above freezing. I realize this wouldn't guard against heavy snowfall blocking the line, but wouldn't this be of some use?

I would guess that this isn't done either due to cost or for some scientific reason which I'm not clever enough to work out...please shoot me down in flames!

 

[ANorthernGuard]

Forgive a stupid question from a layman, but...

In the current cold snap, how come rails aren't heated to prevent ice forming on them?

It would seem that a small element running along the rail could be used, during cold weather, to keep the rail temperature just above freezing. I realize this wouldn't guard against heavy snowfall blocking the line, but wouldn't this be of some use?

I would guess that this isn't done either due to cost or for some scientific reason which I'm not clever enough to work out...please shoot me down in flames!

Cost, Miles of track, Thickness of the rails yadda yadda yadda, and to be honest the railhead has to be practically buried anyway so no point really

 

[142094]

It is not normally the rails thatcause theproblems in this weather (apart from points), it is everything else that goes with them - overhead lines, signalling, and to an extent, the things that actually run on the rails themselves!

 

[bnsf734]

Point Heaters are used to keep points from freezing up. (seemingly with varying degrees of success recently!) Normally powered by propane gas or electricity. They are not fitted to all points due to cost as the previous poster mentioned.

Calv

 

[John Webb]

There is an article in Rail Engineer for December 2010 http://content.yudu.com/Library/A1q4i9/RailEngineerDecember/resources/index.htm?referrerUrl=http%3A%2F%2Fwww.yudu.com%2Fitem%2Fdetails%2F255386%2FRail-Engineer-December-2010 pages 40/41 about adding heating tape to the third rail to keep the ice off. Apparently some 16km of tape has been applied in areas in Kent on a trial basis.

 

[TGV]

They are trialling heating the 3rd rail in places as that causes more problems than the running rails.

Wheels will generally cut through any snow we'll ever see here to find the rails, but like someone else said, it's the S&C, the signals and electrification that dies first.

Overhead lines suffer if they have icicles forming on them, but they can be cleared with the right kit (as they do in the Swiss alps), but in our country we seem to clear them with the first train of the day, mullering it's pan-head on every icicle it smashes into! Then that train fails due to pantograph damage, causes delays.... or pulls the wires themselves down... delays...

Yeah - don't worry about the running rails - they're the least of the problems!

 

[DaveNewcastle]

Overhead lines suffer if they have icicles forming on them, . . . . . but in our country we seem to clear them with the first train of the day, mullering it's pan-head on every icicle it smashes into! Then that train fails due to pantograph damage, causes delays.... or pulls the wires themselves down... delays...

You make it sound just like the toils of Sisyphus!

[Don't ask - he was condemned to the same task over and over again for eternity and could never learn any way out that eternal cycle]

 

[TGV]

You make it sound just like the toils of Sisyphus!

[Don't ask - he was condemned to the same task over and over again for eternity and could never learn any way out that eternal cycle]

Like it! I've seen plenty of destroyed pan carbons that have been scraped along ice-covered OLE at high speed. They don't last long in this weather.

 

[DaveNewcastle]

They don't last long in this weather.

which is exactly the correct way for abrasive contacts to fail.
What isn't desirable when friction is very high is that fixed infrastructure fails.

 

[TGV]

which is exactly the correct way for abrasive contacts to fail.
What isn't desirable when friction is very high is that fixed infrastructure fails.

Yes and No. Yes, it's better that they fail than the OLE, but it's not a desirable operating condition for them either. They should wear evenly and smoothly. They always tend to wear more in the centre because despite the zig-zag pattern of the wire, the centre by definition sees the most contact, but that aside, it should be a smooth and gentle wear pattern.

At this time of year you get large chunks ripped out, and severe pitting from arcing. After a few days it can look like someone has shot at it. In summer you can get weeks of use out of one and it'll look smooth.

In extreme cases in winter you'll get an ADD activation because ice has destroyed the carbon. End of journey.

 

[DaveNewcastle]

. . . . At this time of year you get large chunks ripped out, and severe pitting from arcing. After a few days it can look like someone has shot at it.

Fair enough - there has to be a 'weak link' somewhere, and (as in the multiple functions of a fuse in electric circuirty) surely the carbons are the 'best' component to experience a failure - they're designed, built and fitted to be readily replaced.

In extreme cases in winter you'll get an ADD activation because ice has destroyed the carbon. End of journey.

Now that is something we can learn from. Unlike my example of a fuse blowing (where it shouldn't be replaced until the cause is found and corrected), a component which is designed to fail under stress (not a catastrophic failuer) should be replaceable while on-line. Possible strategies include dual pantos on locos (back to the 1960's I think!) or some as yet unknown strategy for carbon replacement in-the-field.
There are still opportunities for learing and improving our equipment!

 

[TGV]

Fair enough - there has to be a 'weak link' somewhere, and (as in the multiple functions of a fuse in electric circuirty) surely the carbons are the 'best' component to experience a failure - they're designed, built and fitted to be readily replaced.

Now that is something we can learn from. Unlike my example of a fuse blowing (where it shouldn't be replaced until the cause is found and corrected), a component which is designed to fail under stress (not a catastrophic failuer) should be replaceable while on-line. Possible strategies include dual pantos on locos (back to the 1960's I think!) or some as yet unknown strategy for carbon replacement in-the-field.
There are still opportunities for learing and improving our equipment!

Oh yes, the carbons are sacrificial components, but at the same time, they need to have a respectable life. It's a challenge to keep them fresh in this weather when the OLE is often left without any TLC in such icy conditions.

Some units do have a back up pan, but for most (even units with built-in redundancy to power systems like transformer pumps, inverters, etc...) that pantograph on the roof will be a single point failure - mission ends.

 

[ainsworth74]

that pantograph on the roof will be a single point failure - mission ends.

Seems short sighted to only have one, how much extra would it cost to fit a second pan?

 

[TGV]

Seems short sighted to only have one, how much extra would it cost to fit a second pan?

Given that most trains won't have a space free for a pantograph, it would be a modification that would cost thousands per set - well into 5 figures, however, I'm not sure it represents good value for money. While a pantograph failure usually ends a journey there and then - it is still a fairly rare failure mode averaged over the year. It's just more common in poor weather, but is also mainly caused by faulty infrastructure - droppers hanging loose, or dodgy registration arms, etc...

Pendolinos have a backup. As do Eurostars, but most standard 3, 4 or 5 car EMU's don't and fitting one would be prohibitive in my opinion.

 

[ainsworth74]

Given that most trains won't have a space free for a pantograph, it would be a modification that would cost thousands per set

Yeah I thought that retrofitting it onto existing stock would be prohibitively expensive. Would it still be uneconomic to specify it for new build rolling stock, or is it really just not worth it?

 

[thelem]

It does seem excessive to fit two for a 4-car EMU (just look at the amount of equipment involved - every component costs money and weight), but it wouldn't take much to allow a train consisting of multiple EMUs to be able to switch to any of the pantos. I think that's basically how Eurostar works.

 

[TGV]

It does seem excessive to fit two for a 4-car EMU (just look at the amount of equipment involved - every component costs money and weight), but it wouldn't take much to allow a train consisting of multiple EMUs to be able to switch to any of the pantos. I think that's basically how Eurostar works.

Kind of - Eurostar Power cars in common with other dual voltage TGV's have 2 pantographs - a DC one for use in Belgium or South of France and an AC one for high speed line use (or any 25kV lines). Both pans are linked together physically and electrically so that the non-delpoyed pantograph is live at the same potential as the deployed one.

So if the AC pan is damaged, killing that power car, the DC pan can be raised and used at limited speed for a limited time to complete the journey.

Pendolinos, as far as I know, have 2 pantographs that are linked with a 25kV busbar, so if the normal running one fails, you can resort to the second one.

But yes, for a standard EMU - no point in fitting another. It doesn't make economic sense in normal operating conditions.