Lewes and Wickford derailments - rail traceability and could the rail be substandard?

Will the RAIB look into where Network Rail sourced the rails from, that were used in both of these locations?

Are records kept of where supplies of rail come from?

Could there be some rails which are made of substandard steel, which is not as resilient to the recent extreme high temperatures, and if so, can these be traced as to where they originated, and more importantly at what other locations similar rail has been laid?

The rail will be identifiable as to its origin (or should be)

The spec of Railway Rail is very detailed including composition and hardness / ductility.

When I worked at LUL as it was then , we used to analyse every failed rail to ensure it met the spec and were always able to identify its original source from the cast number on the web of the rail.

Kraken Fen said:

Will the RAIB look into where Network Rail sourced the Rails from, that were used in both of these locations ?
Are records kept of where supplies of Rail come from ?
Could there be some Rails which are made of sub standard steel which is not as resilient to the recent extreme high temperatures and if so can these be traced as to where they originated and more importantly at what other locations similar rail has been laid ?

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In both case the rail is unlikely to be the problem, the underlying issue will likely be differential settlement of the ground as it has been drying out.

Yes the standards specify that every 4m or less the following has to be rolled on to the web for traceability (belt and braces solution combined with good record keeping):
Manufacturer code (e.g. BS = British Steel)
Plant code (e.g. SC = Scunthrorpe
Steel grade (Pictorial for different grades so you have to decipher but will probably be R260)
Year of manufacture (e.g. 26 = 2026)
Profile code (e.g. 56E1)

Effectively all plain line flat-bottomed CWR will have come Scunthorpe in the last 2 decades and Workington before then.

Kraken Fen said:

Will the RAIB look into where Network Rail sourced the Rails from, that were used in both of these locations ?

Click to expand...

Yes

Kraken Fen said:

Are records kept of where supplies of Rail come from ?

Click to expand...

Yes

Kraken Fen said:

Could there be some Rails which are made of sub standard steel which is not as resilient to the recent extreme high temperatures

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Very, very unlikely.

The stress in CWR at high temperatures will depend on the thermal coefficient of expansion, and that will be more or less the same for any grade or alloy of steel.

Torfaen said:

The stress in CWR at high temperatures will depend on the thermal coefficient of expansion, and that will be more or less the same for any grade or alloy of steel.

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Define "high temperatures"

In the case of steel, 40°C (for arguments sake as that's 20°C above the nominal 20°C baseline) it's just under ¼mm per metre, or so

Not sure what a realistic track surface temperature is... there's a lot of length to conduct heat, but most track is in the open so susceptible to radiation absorption.

Farnborough said:

Define "high temperatures"

In the case of steel, 40°C (for arguments sake as that's 20°C above the nominal 20°C baseline) it's just under ¼mm per metre, or so

Not sure what a realistic track surface temperature is... there's a lot of length to conduct heat, but most track is in the open so susceptible to radiation absorption.

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It's widely reported that rail can get to 20 degrees above ambient temperature on hot days, depending on various factors such as how sheltered it is from the sun.

The stress-free temperature used in the UK is 27 degrees I believe, so the rail needs to cope with compressive stress of expansion up to around 60 degrees.

Below the stress-free temperature the rail is in tension, so it has to be set to take account of the risk of breaking when it's very cold (which also makes the rail more brittle).

Farnborough said:

Define "high temperatures"

In the case of steel, 40°C (for arguments sake as that's 20°C above the nominal 20°C baseline) it's just under ¼mm per metre, or so

Not sure what a realistic track surface temperature is... there's a lot of length to conduct heat, but most track is in the open so susceptible to radiation absorption.

Click to expand...

Track buckling is a factor not only of rail temperature, but also the type of rail, the ‘fixity’ of what the rail is attached to, localised conditions of what the sleepers ate in, localised curvature, and other factors.

The permanent way maintenance manual has a table that provides expecred rsil temps above ambient in different cloud cover conditions and different times of year. The maximum expected is +18C.