Reason for wavy line on track

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ryan125hst

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I went to Railfest on Thursday and while waiting for my train home, I noticed something strange on the track. I was just returning from the toilet and was walking past platform 8 when I saw a silver wavy line on the track. I wondered what the purpose of it is. Platform 8 at York is a bay platform as many of you will be aware. I thought it was some sort of warning that the train is close to the buffers (does it cause the train to vibrate in a similar way to the warnings on motorways?) I then realised that the Pacer that uses the bay would stop on these as they continued for a short while down the platform, so thought this might not be the case.

I decided to take a photograph of it to put on here (it should be attached if I have done it right!). The photograph was taken on platform 6 (which had the same wavy line on the track) as platform 8 was almost empty so I thought I would look a bit odd.

Any ideas what it is for?
 

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slick

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Track circuit continuity welding, aka zig-zagging, aka eutectic strip is to make sure the track circuits still work in little used and contaminated areas.

These are also present on the DC lines at the buffer stops of platforms 9 and 10 at Euston. Would there be another reason for these at this location? Because both platforms are used by at least 4 trains per hour and contamination isnt an issue as euston has a canopy?

Or perhaps they date back from a time where those two reasons were an issue?
 

Ploughman

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As has been explained in another version of this same question earlier this year.
The rail in little used areas such as the approach to buffers and emergency crossovers frequently rusts over quite thickly or gets covered in oil, grease etc.
The weld strips are slightly raised above the rail surface and when a wheel set passes over it cuts through the rust and oil etc giving an increased likelihood of the track circuit showing the correct indication.
Most people notice them because of the rumble but that is not the purpose.
 
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The welds appears to be using a steel/nickel / chrome alloy. This will reduce rusting. Ideal for track circuiting.
Imo the wavy line could, if anything reduce adhesion (as a smaller part of the wheel is in contact with the rail) but so does rust and grease etc!
 

Greeny

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It is for track circuiting – where there is a risk of the T/C failing to show occupied when a train is present. Usually found on the approach to a buffer stop or other places where there is a risk of a ‘wrong side’ failure. But ........ it’s bloody expensive, my old boss used to say that the S&T would pick a number from a ‘phone book and put a ‘£’ sign in front of it.

G.
 

Trog

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There was a plan a few years ago to replace the welded on zig zag with two strips of stainless steel let into slots cut in the rail head. But I have never heard any more about it, so I guess that died a death. Often as well as the zig zag you will see the initials of the welders who put on the strip.

I have been told it is done as a zig zag because it is a very hard metal, and if it was done in a straight line down the middle of the head there was a risk that it could over time damage the wheels.
 

Joseph_Locke

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I have been told it is done as a zig zag because it is a very hard metal, and if it was done in a straight line down the middle of the head there was a risk that it could over time damage the wheels.

Or possibly, as I was once advised, it is zigged-zagged to stop it peeling off and winding itself around the wheels.

It is stainless steel, so your reason sounds good too. Could it also be to maximise adhesion, in the way that a weld-width strip longitudinally along the head wouldn't?
 

Crossover

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But ........ it’s bloody expensive, my old boss used to say that the S&T would pick a number from a ‘phone book and put a ‘£’ sign in front of it.

Why is it so expensive? Just time consuming to fit etc?

I think most of the replies on here cover everything else, that it is there to aid the signalling systems in not losing trains (which happens on rusty rail)
 

GB

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Can't imagine the reason for the zig zag over straight being potential wheel damage for the very point of their existence being in places that do not see much traffic.

Zig Zag probably offers better conductivity?
 

Crossover

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It was hand applied by an aged technician using an arc welder with a stainless steel rod in it; a typical run is about 60 feet of welding on each rail!

Thanks for that - makes sense :)

Can't imagine the reason for the zig zag over straight being potential wheel damage for the very point of their existence being in places that do not see much traffic.

Zig Zag probably offers better conductivity?

I would guess so. More surface area to pick the train up on so less chance of it still getting lost from the track circuit
 

Trog

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The contact area between rail and wheel is so small that it probably makes little difference to how much contact there is between wheel and strip.

As for how much traffic it gets, how often would the wheel sets on the south end of a Euston Watford DC unit run up onto the strips at Euston.

The concept of putting the strips at buffers is a bit dated in these days of fixed formation trains anyway. How often does the signalman at Wembley need reminding that there is a horse box (marked 10'-0" XP of course) or a GUV full of parcels up against the stops at Euston waiting to be attached as a tail load to the next Pendolino to Glasgow. Even having a thunderbird loco there after dragging in a failure must be quite rare.
 

Joseph_Locke

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How often does the signalman at Wembley need reminding that there is a horse box (marked 10'-0" XP of course) or a GUV full of parcels up against the stops at Euston waiting to be attached as a tail load to the next Pendolino to Glasgow. Even having a thunderbird loco there after dragging in a failure must be quite rare.

But we both know that isn't how the railway head thinks: there are vehicles that short (relieving bogies on 75t cranes?) so we must plan for them...
 

Greeny

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There is a very good reason why zig-zags are used rather than straight lines. Unfortunately I don’t remember what it is as some kind soul nicked my Signalling Principles. As I recall though, the Welder who made them (in stainless steel) was provided with a ‘stamp’ to press into the weld to identify him later. It was something like the ‘stamp’ issued to ‘Thermit’ Welders. As I remember, the old brown stuff hit the fan with a vengeance after the Bushey derailment when it was found that the ‘stamps’ were not being used by some Welders. So there was no individual upon whom to hang the blame.

I believe that the reason for the zig-zag being provided goes back to the days when, at terminal stations, trains were loco hauled and the loco on the arriving train hooked off at the buffer stops, while another loco attached to the (now) front of the train. If the loco at the buffer stop did not immediately follow the departing train to the platform outlet signal, it could disappear from the track circuit when the departing train cleared the platform track circuit with the result that the next train in could enter the platform on a proceed aspect rather than ‘cats eyes’ which, at best could give the Driver a nasty fright. That was also in the days when trains used to get a green aspect to enter an ‘empty’ terminal platform.

G
 

Joseph_Locke

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"Eutectic strip" - that's a rather unusual use for the word eutectic. Can anyone explain why ?.

It is, isn't it. I have no idea, as the concept of "a mixture of chemical compounds or elements that has a single chemical composition that solidifies at a lower temperature than any other composition made up of the same ingredients. This composition is known as the eutectic composition and the temperature is known as the eutectic temperature." (wikipedia) doesn't seem relevant to me either.
 
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hwl

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It is, isn't it. I have no idea, as the concept of "a mixture of chemical compounds or elements that has a single chemical composition that solidifies at a lower temperature than any other composition made up of the same ingredients. This composition is known as the eutectic composition and the temperature is known as the eutectic temperature." (wikipedia) doesn't seem relevant to me either.

Stainless Steel has relatively poor thermal and electrical conductivity compared to most metals or alloys (copper Aluminium or regular steels) and weld deposited isn't likely to be that hard (or therefore have good wear resistance), indeed it is likely to be softer than the normal rail steel.

Given what other are sayings it sounds like they are using a eutectic composition nickel chrome alloy (Ni53% Cr47% possibly with a small amount of other additives such as silicon) which would be much harder as weld deposited in situ than rail steel (x2?) and has excellent corrosion resistance, wear resistance and electrical conductivity. The eutectic composition would have been specifically chosen for the ability to produce high quality insitu welds easily (quite tricky as the rails suck the heat out too quickly - far less of a problem for a eutectic composition).

The welding rod would be pretty expensive.

Other Ni-Cr alloys are used for corrosion resistant / high temperature electrical wire (max 20% cr.) for example in heating elements.

Another example of a eutectic alloy is electrical solder (but not plumbing solder).
 

Joseph_Locke

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Stainless Steel has relatively poor thermal and electrical conductivity compared to most metals or alloys (copper Aluminium or regular steels) and weld deposited isn't likely to be that hard (or therefore have good wear resistance), indeed it is likely to be softer than the normal rail steel.

Given what other are sayings it sounds like they are using a eutectic composition nickel chrome alloy (Ni53% Cr47% possibly with a small amount of other additives such as silicon) which would be much harder as weld deposited in situ than rail steel (x2?) and has excellent corrosion resistance, wear resistance and electrical conductivity. The eutectic composition would have been specifically chosen for the ability to produce high quality insitu welds easily (quite tricky as the rails suck the heat out too quickly - far less of a problem for a eutectic composition).

The welding rod would be pretty expensive.

Other Ni-Cr alloys are used for corrosion resistant / high temperature electrical wire (max 20% cr.) for example in heating elements.

Another example of a eutectic alloy is electrical solder (but not plumbing solder).

In 24 years that's the best explanation I've ever heard - thank you!
 

Trog

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Sounds good to me too, although another option could be that the strips were originally made with a eutectic alloy, and the name has stuck in a more generic fashion the same way Dyson make hoovers.
 

hwl

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Sounds good to me too, although another option could be that the strips were originally made with a eutectic alloy, and the name has stuck in a more generic fashion the same way Dyson make hoovers.

Possible but unlikely, though i'll keep an open mind.
[I originally had a metallurgy and mech eng background (completely non railway)]
Both Stainless and the eutectic alloy would be Arc weldable.
Having used P8 at York twice a fortnight for the last 3 years and having stared at the wavy line that kicked this thing off wondering what it purpose was and why the stuff was significantly harder than the rail steel (given the wear pattern (or comparative lack of wear on the strip!) which doesn't align with stainless. If it were stainless it would probably be 308L welding rod which is pretty soft and wears easily.
The welding rod cost for doing the job with stainless (assuming zero losses) is ~£450 which even with lots of labour is barely going to break 5 digit cost , custom eutectic rods on the other hand would get to 5 digits without labour, which seems to align better with eye watering costs described.
Going back to the dark ages, it would also be possible to apply the eutectic with an OA torch but not the stainless.

Will try to take some more photos on Friday.
 
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