british train tracks melting in the sun?

according to the BBC
today’s record heat is causing problems:

“Heat caused railway lines to buckle in the Midlands on Tuesday and many services from New Street Station in Birmingham were cancelled. Speed restrictions were in force on the West Coast Main Line”

but it was only 36 degrees! (=97 F)

Now, I know the Brits aren’t used to such heat—but, gee whiz, most of the civilized world is used to it. And the steel in the railroad tracks can’t be that much different from the steel used in American railroads. Yes, I know that engineers design to meet local code requirements, which are based on local weather conditions. But there is always a factor of safety. Usually, engineers make their calculations to withstand double the expected strain. So you would think that the engineers allowed for heat expansion when they designed the steel rails.

I know a bit about concepts like coefficient of expansion, design loads, deflection, the stress-strain curves. (Well, actually, I’ve forgotten whatever I once knew, but I can still use a few fancy words …

so—my question for civil engineers is:
Why did 36 degree heat cause so many problems? Would the tracks have withstood, say, 35.5 degrees with no problem? And aren’t train tracks pretty much the same all over the world?

IANA engineer, but the tracks buckled, they didn’t melt. Any metal object will expand in heat - even 36-degree heat. This is why bridges have gaps, so they can safely expand and contract. I’d guess that those particular tracks were not built in a way to withstand that kind of heat, and without the opportunity to safely expand, they warped. The force of the metal expanding greatly overpowers the force holding them to their ties, so the whole track becomes unusable.

A quick google for ‘buckling rails heat’ turns up this simple BBC account, and this which seems to know what’s going on (although I only skimmed it and may not understand it anyway). It looks like (a) no, the treatment of continuous welded rail isn’t always the same, but depends on local expectations for temperatures, and (b) the usual story of poor maintanance, bad management, short-term costcutting, etc.

The problem is not unique to british rail lines. It happens here too.

A friend who works for a RR says that today’s modern welded rails is actually more likely to buckle than the older rails that had joints every X feet. No room to grow in warm weather. But the trade off is it’s a lot quieter.

RR track crews frequently use heat to expand rails to fill small gaps.

yes, I know that’s what happened–but my question is WHY didnt the engineers leave the standard gap between the rail sections? 36 degrees is not so extreme, even in the cloudy climate of England where 34 degrees is expected. And apparently, most other British railroads survived today. Doesn’t England have a basic engineering code for road/rail design that takes into account their local weather, plus a factor of safety?

The point of CWR is that there aren’t any gaps. Google it.

It was the wrong kind of sun.