Deforming railway tracks?!

[brightspark]

It doesn't need gaps, its continuous welded rail, if they left gaps it wouldn't be continuous.

The stress in the rail will be well within the strength of the steel, the issue if the ballast isn't maintained properly (Or the rail gets hotter than was intended) then the sleepers can move and the rail gets a kink.

so why is the track all welded and theres a fishplate joint outside my house on a slight bend

 

[optima21]

and of course you can take advantage of the linear expansion of metal, without that we wouldn't have the bi-metallic strip that is used for temperature controlled switches and thermostats

 

[rikrobson]

And I suppose 35 degrees Vs 25 degrees is 40% hotter in percentage terms.

You can base a percentage on an arbitrary mid point of 0 degrees. Consider the Fahrenheit scale with a different 0 and the kelvin scale with a absolute 0

 

[8ob]

It doesn't need gaps, its continuous welded rail, if they left gaps it wouldn't be continuous.

The stress in the rail will be well within the strength of the steel, the issue if the ballast isn't maintained properly (Or the rail gets hotter than was intended) then the sleepers can move and the rail gets a kink.

You cant run miles of track without expansion joints, it would be impossible to contain it with the range of temperatures its expected to operate in.

 

[James1979]

You cant run miles of track without expansion joints, it would be impossible to contain it with the range of temperatures its expected to operate in.

Always wondered what they were

 

[Robotstar5]

There was a news item about the heat and the rails, they showed some workers painting the sides of the track white to reflect the heat.

I knew a permanent way worker, he showed me the chart they use when jointing (welding) the rails, when they cut the rail it springs open, then they reference a temperature chart and measure the gap, cut off what's needed to match the chart then pull the gap up and thermite weld it.

 

[eLuSiVeMiTe]

There was a news item about the heat and the rails, they showed some workers painting the sides of the track white to reflect the heat.

I knew a permanent way worker, he showed me the chart they use when jointing (welding) the rails, when they cut the rail it springs open, then they reference a temperature chart and measure the gap, cut off what's needed to match the chart then pull the gap up and thermite weld it.

 

[tigdlo]

If rail track increases in length 11µm for every 1°C then a 20m length of track will be 2.2mm longer at 35° than at 25° this will cause it to create an arc 128mm high.

According to this online calculator, HERE

 

[Beeezer]

On a hot sunny day there’s a door I can’t open on my boat because the steel expands.
I very rarely need to open this door till after six but today had to give it a boot.
I really should sort but after today I enjoyed kicking it..

 

[SierraV6]

I suppose with miles of continuous track even a small expansion per m of track adds up. And I suppose 35 degrees Vs 25 degrees is 40% hotter in percentage terms.
What do they do in places like Africa, India or Australia where it's always hot?

One of the solutions is to lay track at a higher stress temperature

But then it goes into tension.

In the UK it’s designed to be stress-free at 27C (that’s the surface temperature not the ambient temperature). This varies from country to country for obvious reasons. The point at which mitigations are required due to an increase in temperature is dependant on track condition, curvature etc. but there’s a set tolerance for “perfect” straight track which provides a starting point (don’t ask me what it is!) and it’s all worked out from there.

 

[Kayos]

People forget that we have never had these temps in the UK

(Please don't start with '76, that was 10 degrees cooler)

The tracks were designed for a working temp plus a bit it margin, we are exceeding the margin

A river in Germany is drying up, complaining the massive barge can't transport coal down it. Cause and effect anyone?

 

[highseas]

I have about 500 fishplates and 15 ton of rail at my disposal if BR want to talk Ile sthill saw some joints in to keep the country flowing

 

[Bravheart]

Think I heard yesterday the rail track is designed for Temperatures between-20 and +30 c. Anything else needs treated with caution and don't forget the overhead wires the same applies apparently.

 

[awemawson]

Overhead railway wires are held in tension by weight sets. The end goes over a pulley and the weights go down and up with temperature changes.

 

[SierraV6]

Think I heard yesterday the rail track is designed for Temperatures between-20 and +30 c. Anything else needs treated with caution and don't forget the overhead wires the same applies apparently.

See my post above (#30) above. I can find out some more details if anybody is interested as I have a reliable source.

As per @awemawson’s post the wires are kept in tension by weights. If they make it to the floor we have serious issues! (They won’t, just to be clear).

 

[GRW]

I recall as a child (may have been '76 but not certain) looking over the side of the Railway Bridge above Bancyfelin in Carmarthenshire, Wales (Carmarthen-Fishguard Line) - and seeing both tracks had buckled to the point where it looked like British Rail had added a couple of chicanes for the Trains.

 

[mike os]

You make a piece of steel a mile long then wonder why it buckled in the heat?

I’m not the sharpest tool in the box but even I can work that one out

Isn’t it about time they sorted this one out ? After all we have been told we are having more of this for the last 50 years.

 

[Fred Trevvett]

You can base a percentage on an arbitrary mid point of 0 degrees. Consider the Fahrenheit scale with a different 0 and the kelvin scale with a absolute 0

True. I suppose I was talking in terms of heat energy in the rail, measured in joules

 

[Parm]

Years ago I did a big project with network Rail looking at HAVs risk. Since they started welding the track for a smoother journey they also have to do a lot of grinding to fettle the thermic welds

Rail track workers have very high HAVs riddor’s

 

[voipio]

so why is the track all welded and theres a fishplate joint outside my house on a slight bend

On a bend, the expansion of continuously welded track would force the bend outwards, resulting in quite a bit of sleeper movement as the track warmed and cooled. At least the fishplate allows expansion without too much distortion. On straight runs, keeping the track as straight as possible allows compressive forces to build up in the steel without the track kinking. Think of a piece of wire e.g. TIG welding wire. If it's perfectly straight, quite a bit of compressive force can be applied. As soon as it has even a slight kink, the wire bends easily when longitudinal compression is applied.