Freezing temperatures affecting the railway infrastructure?

[londonmidland]

I’ve noticed over the past few days, there has been infrastructure issues during the morning. Today in particular, there are various points and signalling failures across the rail network. The most disruptive ones being between Watford and Euston and between Birmingham and Bristol.

Last night we had the coldest overnight temperatures for a fair few years, with lows widely around -5 to -7, with some places going as low as -10.

So is it just a coincidence that these failures are occurring over the past few days or is the freezing weather having an impact on the infrastructure and how it operates?

 

[56xx]

South Wales Valley Lines currently all suspended due to multiple signalling failures

 

[gabrielhj07]

So is it just a coincidence that these failures are occurring over the past few days or is the freezing weather having an impact on the infrastructure and how it operates?

Very much doubt it's a coincidence, opening a car door that's been sat for a few days gives a good idea of the problems ice & frost can cause.

== Doublepost prevention - post automatically merged: 15 Dec 2022 ==

You can tell a set of heated points in this weather by the lack of frost on them.

 

[zwk500]

So is it just a coincidence that these failures are occurring over the past few days or is the freezing weather having an impact on the infrastructure and how it operates?

Freezing weather will definitely be having an impact, cold conductors will be less efficient and movable parts like point/switch blades will contract and not throw/detect correctly. And then there's the extra brittleness that cold brings, cold/frozen oils and lubricants etc, just to start.

 

[Ediswan]

Freezing weather will definitely be having an impact, cold conductors will be less efficient and movable parts like point/switch blades will contract and not throw/detect correctly. And then there's the extra brittleness that cold brings, cold/frozen oils and lubricants etc, just to start.

How does that work ? For the materials used, electrical resistance increases with temperature. A cold conductor will be a (slightly) better conductor.

 

[Bald Rick]

So is it just a coincidence that these failures are occurring over the past few days or is the freezing weather having an impact on the infrastructure and how it operates?

It’s the cold and (specifically) icy weather.

Points heating failing, icicles on the OLE, ice on the con rail system causing shorting (several examples over the last few days), etc. etc.

 

[zwk500]

How does that work ? For the materials used, electrical resistance increases with temperature. A cold conductor will be a (slightly) better conductor.

I'm not 100% sure tbh, I might be totally wrong on that point. Thinking about it now it does seem slightly counter-intuitive

 

[Bald Rick]

Another point is that in this sort of wether it just takes longer to fix faults. It takes longer to get to site (some of the lanes to access points will be treacherous, as will walking routes trackside), and then actually doing the work is more difficult.

Imagine having to rewire a light fitting, outside in this weather, in the dark, with a torch for help, and compare to doing it on a May evening.

 

[Dai Corner]

Apparently icicles in Chipping Sodbury tunnel mean a 10mph speed restriction and consequent delays for trains between Bristol Parkway and Swindon.

Sapperton Tunnel between Swindon and Cheltenham is closed for the same reason.

 

[Matt_pool]

The Merseyrail network ground to a halt during rush hour this morning due to "Freezing Conditions" and still isn't back to normal.

 

[dk1]

Few onboard toilets out of use but that’s about as bad as it’s got here in Norfolk & Suffolk.

 

[Western 52]

Yesterday TfW tweeted that point failures were caused by the heaters failing due to the cold weather....really?

 

[Rescars]

I recall a senior traffic manager back in the late seventies speaking wistfully about the effectiveness of using steam locomotive equipped with a steam lance for deicing activities. Not an ideal tool to apply to 21st century electronics I imagine!

 

[Annetts key]

Yesterday TfW tweeted that point failures were caused by the heaters failing due to the cold weather....really?

I think that message has been dumbed down. Point heating fails due to a number of reasons, but not normally due to the cold weather. However, faulty/non-functioning/partly working/failed point heating does not cause any problems if it’s not freezing weather. And obviously, if there is a point that is not provided with point heating (yes, they exist), that may be affected by freezing temperatures or snow.

I’m not up with the current maintenance standards, but it used to be, and may well still be the case, that point heating should be tested in the autumn to check to see if all heating elements are operational and for any other defects.

== Doublepost prevention - post automatically merged: 16 Dec 2022 ==

I should also point out, that due to expansion and contraction of the metal components, a point or part of the mechanism may move out of specification, which then results in a failure. Especially if there is an existing problem.

 

[DarloRich]

I recall a senior traffic manager back in the late seventies speaking wistfully about the effectiveness of using steam locomotive equipped with a steam lance for deicing activities. Not an ideal tool to apply to 21st century electronics I imagine!

Irc the winter development vehicle in scotland has steam lances fitted.

 

[alxndr]

There's also been quite a few point failures here which seemed to be due to the temperature of the hydraulic fluid. The fluid is marketed as being suitable for wide variations in temperature but the temperature-viscosity graph cuts off above the temperatures we dropped to.

 

[Trestrol]

The Tyne and Wear Metro had a broken rail on the cast crossing on a set of points this week. In my experience point heaters never work in the winter, plant spend all year fiddling with them and still they don't work.

 

[Ducatist4]

How does that work ? For the materials used, electrical resistance increases with temperature. A cold conductor will be a (slightly) better conductor.

Batteries don't work well when the temperature drops - maybe that's where the confusion is.

 

[Bill57p9]

Metal contracts as it gets cold, so gaps can open up in joints, such as connectors.
Electrics & electronics have a design minimum temperature for this reason, amongst others.

 

[Annetts key]

Not really had too many problems with hydraulic oil operated clamp locks. Do however sometimes get reports of hydraulic operated level crossing barriers being slow (it can be annoying for the signaller/crossing keeper as most crossings will ‘time out’, then they have to operate the controls to restart the sequence).

Similarly, at least in my part of the world, we don’t get many problems with cells or batteries during the cold weather, not for signalling equipment (the cold does affect the cell(s) or battery in mobile telephones though). In fact, cell(s) or batteries used for signalling and points systems are more likely to fail during really hot weather.

Or any noticeable problems with electrical connections. Railway signalling (at least in the past, I’m not so keen on some of the current ‘modern’ connectors) used very rugged connection methods. Of course if the installation was poor (screw terminals not properly tightened for example), then yes, sometimes failures would occur during cold weather.

The biggest problems during cold weather are the obvious ones: ice or snow obstructing moving items such as the switch rails on points. Or ice formation (due to condensation) on electrical ‘switching’ contacts (in mechanical signals, point machines, barrier or ground frame circuit controllers and similar).

Ice is also a particularly bad problem for wet tunnels, and double trouble if they have OHL conductor rails… This was the problem on the Western Route last week.

Extremes of temperature (hot or cold) are more likely to be enough to cause electronic equipment that had unknown existing problems (that were already developing) to fail sooner than it would have otherwise.

Overall, I would say that from a signalling equipment perspective, water (as in rain water, condensation and flood water) are more of a problem than temperature (high or low).

 

[alxndr]

Not really had too many problems with hydraulic oil operated clamp locks. Do however sometimes get reports of hydraulic operated level crossing barriers being slow (it can be annoying for the signaller/crossing keeper as most crossings will ‘time out’, then they have to operate the controls to restart the sequence).

I used to be in the same bit of the world as you and had no issues with clamplocks either, but now being in Scotland I've heard of 4 or 5 cases this year. It is of course quite a bit colder up here. They started making a whistle (like an old style kettle on the boil) and the locals agreed with my hypothesis that about the temperature. I don't know if draining the system and replacing the fluid would solve it or if it causes internal damage as they tend to go for pump unit replacement for speed.

Overall, I would say that from a signalling equipment perspective, water (as in rain water, condensation and flood water) are more of a problem than temperature (high or low).

I don't think I saved the graphs but I did once make a rough graph of SSI failures reported per month of the year and found a definite trend towards the hotter months, so temperature has some bearing. There's also likely to be more issues with points failing due to the facing point locks needing adjustment when the temperature changes due to expansion/contraction.

More generally speaking some track work has to be delayed if the rail temperature drops below a certain level, so although it doesn't directly cause an immediate delay, it doesn't help the overall state of the railway.

 

[Annetts key]

Agree mate.

Yes, it’s normally considerably milder in the South West of England compared to Scotland or the north of England. Including different lengths of the seasons (for example spring as far as nature is concerned starts visibly earlier here).

I think you may have partly misunderstood what I was saying. Yes, we have had trouble with clamp locks during really cold weather. But more trouble and more often with WR barriers. Completely changing the oil will help if the existing oil is contaminated. But as you say, if that does not work (and that itself is not very easy, at least, getting all of the old stuff out), the next step is to replace the power pack.

My point was supposed to be that water can, and does cause problems all year round. And can affect many types of equipment. At this point I would love to list some interesting-ish examples. But won’t, just in case it gives trouble makers any bad ideas.

But I can tell you that if water gets into the gear box of certain types of point machine (for example M3 and HPSA types especially) and then freezes, that’s that point out of action. For HPSA types, often until a new gearbox is fitted. Even if the water does not freeze, eventually affected HPSA types will eventually fail.

In regards to electronics like SSI and similar systems, yes, they are more likely to fail during very hot weather. Or for equipment inside accommodation, when the occupants have the the heating on full! But I thought I covered this in my second from last paragraph.

Ironically, with regards to point heating, the worse case is if some heating is working, but not all. It can result in lateral movement of the switch rail compared to the stock rail. I’ve had far too many P.Way stud bolt heads hitting against the heads of the point operating equipment bolt heads due to this, which prevents the switch rail from property fitting up to the stock rail (causing failures that can’t easily be fixed).

 

[alxndr]

I think you may have partly misunderstood what I was saying. Yes, we have had trouble with clamp locks during really cold weather. But more trouble and more often with WR barriers. Completely changing the oil will help if the existing oil is contaminated. But as you say, if that does not work (and that itself is not very easy, at least, getting all of the old stuff out), the next step is to replace the power pack.

Apologies, I don't deliberately intend to be contrarian, it's just very often that your posts spark off other thoughts in my brain. Plus I was quite astounded by how poorly clamplocks seemed to fair up here, having gone from never really seeing them having problems with winter weather (outside of the typical non-weather related failures) to hearing of several in the space of a week. That said, my sample size isn't great and I only experienced BR843 barriers on the Western, and have no barriers to deal with at all now.

My point was supposed to be that water can, and does cause problems all year round. And can affect many types of equipment. At this point I would love to list some interesting-ish examples. But won’t, just in case it gives trouble makers any bad ideas.

But I can tell you that if water gets into the gear box of certain types of point machine (for example M3 and HPSA types especially) and then freezes, that’s that point out of action. For HPSA types, often until a new gearbox is fitted. Even if the water does not freeze, eventually affected HPSA types will eventually fail.

In regards to electronics like SSI and similar systems, yes, they are more likely to fail during very hot weather. Or for equipment inside accommodation, when the occupants have the the heating on full! But I thought I covered this in my second from last paragraph.

I did work somewhere which apparently had a disproportionate amount of SSI module faults, so maybe that's coloured my view a little. In the summer we could easily do a regular month's worth of failures in a week just on SSI modules. Perhaps we can agree that for 3/4 of the year water-related issues are the most prevalent weather connected problem, and in the summer it's the temperature?

 

[Annetts key]

I think for my area at least, it’s quite difficult getting a reasonable overall picture of failure trends at the moment.

It also depends on what mixture of equipment you have…

Due to most of our area having experienced resignalling or substantial alterations over the last decade, I would say we are still on the sloping edge of the bath tub curve. Even if some of the so say new equipment is actually ‘serviced’ SSI (Solid State Interlocking) modules.

Actually thinking about it, even before that, we have not had long periods where no alterations have taken place. The railway have always been doing something somewhere.

The SSI modules (which were all brand new when originally installed) of the oldest scheme do appear to be far more reliable than those of the latest scheme. Note that the latest scheme covers a considerably bigger area.

On the latest scheme, a lot of the TFM (SSI Track side Functional Modules, such as signal or point types, housed in cabinets rather than actually being next to the track) appear to be serviced units rather than brand new units. The datalink and LDT (Long Distance Terminal telecommunications) modules are new. But lots of all have been replaced due to failures. With the datalink modules especially, there is a known difference between the reliability of the two different makes. With most of them being the less reliable make…

But due to most of these SSI modules failing at random no matter the weather, it’s hard to link any to high temperatures.

ASTER U type/SF15 type transmitters and occasionally receivers (parts of audio frequency jointless track circuits) were in the past the most likely to be affected by really hot summer days. But once the faulty item had been replaced, the same TC would be reliable for years afterwards.

TDM (Time Division Multiplex - a form of remote control system) or equivalent systems definitely work more reliably if not cooked. Similarly, axle counter ACE (axle counter evaluator) racks also are more reliable if the cubicle doors are permanently left open (or removed) and the air conditioning is operational and effective (the company have installed some extra permanently fitted AC units in some REBs).

UPS equipment also does not like being cooked.

I can’t, off the top of my head think of anything else that is especially cold or heat sensitive (apart from IRJs being affected by rail expansion) at the moment.

I do know that ASTER U type/SF15 type transmitters and receivers, signal flashers (for flashing aspects) and similar equipment will be affected by water getting into them.

Apart from flooding, physical damage from yellow painted things and telecommunications cables faults, the small number of AzLM H type axle counters that we had were very reliable. Not so for the new K type. But note that we do have thousands of these now.

They are all new equipment. The K type EAK (electronic junction box) is rubbish, if the case ‘cover’ (its on the ‘front’ side) is not done up fully, rain water leaks in the top and dribbles down over the PCB affecting the electronics. Condensation can also cause trouble.

The telecom type cables for these terminate in dis-boxes where Wago terminals are used exclusively. Some of these suffer badly from condensation (being a dis box, they don’t have 110V AC supplies so no case heater). Even resulting in terminals less than five years old having to be replaced.

On part of our area, we have modular conventional colour light signals. I call them modular because they are designed so that you can directly bolt multiple heads together vertically. Unfortunately that means that the seals in the top of every single one have to be perfect. They are not. So rain water finds it’s way in, dribbles over the electrical parts, and then the SSI module will shut down it’s output interface causing a critical alarm and a red signal that the signaller can’t clear.

AWS electro and suppressor magnets love to fill up with water, and hence test earthy…
I once had one where the water was right to the top, perfectly clear. Hence I did not notice until I went to put my hand in to check the tightness of the wiring! Got a bit of a surprise!

And then there are all the rubber multicore signalling cables that eventually turn to a poor impression of a sponge…

And of course, then there are the track circuits that fail due to poor ballast conditions (or should I say mud consistency for some…) and the points that fail when the water the mechanism is in freezes, or the mud builds up on the slide chairs.

Sorry, gone a bit off topic and into ramble mode. I’ll stop now.

 

[Bald Rick]

As rambles go - that was very interesting and informative!

 

[Annetts key]

As rambles go - that was very interesting and informative!

Thanks

 

[High Dyke]

Yesterday TfW tweeted that point failures were caused by the heaters failing due to the cold weather....really?

Point heaters. You're lucky. Many areas I cover don't have that luxury, we just fetch the lad from out chimney and tell 'im to chip the ice off wi' a pick axe.(apologies to the Four Yorkshire Men).

Back to the topic. Places I've worked during the last few weeks, have been relatively trouble free. Did have odd problems with access gates; frozen padlocks or cold fingers trying open them.