Extreme heat house damage?

Anything on a clay soil subsiding...

Some things are covered by insurance. Subsidence is, but a melting roof probably isn't.

I wonder what the national speed limit on the railways will be, before they have to stop trains falling into the gaps of sprung rails

Then put water on it if it's the flat roof with white pebbles.

They are designed to hold water to stop the melting.

Bit of a bastard if it's on the 4th floor etc but if its a single storey then get out the hosepipe

Plus. of course, on any hot, sunny day, fire from sunlight on a concave (saving / makeup) mirror being focused on something flammable.

I wonder if there are any risks for engineering structures older than a few decades ? I know rails can buckle, and what temperatures do expansion gaps work up to ?

Probably in my ignorance I thought rail track these days was continuous welded and no longer had expansion gaps, or at least if they do, they're a lot fewer, and the rails are pre-stressed before finally clamping to the sleepers to accommodate some of what would otherwise be expansion.

Question: how much do 300 miles of track expand between 5 and 40°C? Will Penzance get pushed into the sea?

That doesn't stop them buckling though. Problems start when the rails reach about 46C, which is not uncommon with an air temperature of 30C. Remote monitoring detects when rails are expanding too much and speed restrictions are put in place, which reduces the risk of the rails buckling under the load of a train passing.

Not quite. It's about 610 feet (assuming the coefficient of expansion is

Does your calculation allow for (a) the pre-stressing of the rail so its "stress free" temperature is 27 degrees and (b) the compressibility of the rail as Penzance resists being moved closer to Quebec?

Yes they pre-stress the rails - basically they are heated if necessary during installation to achieve neutral stress on an warm day, but not a very hot one.

Old style rail had small expansion gaps between each length of rail, where they were joined by the lubricated and bolted fishplates:

And, how much does the land that it is on expand?

What happens is that the rail is welded to be zero stress at the average annual temperature, so it may buckle in extreme heat if the ties to the sleepers fail. This is mostly a problem where annual temperature range is massive, such as Canada.

:-)

I was somewhat surprised that the SFT is as low as 27°C. I would have thought that even on an "average" hot day the rail temperature would be way above 27°C (or is that meant to be the air temperature?). The stainless steel cover of my BBQ gets far too hot to touch after an hour in the sun. Rails are darker and less reflective on the sides, and should heat up even more.

Perhaps Chris could go out and photograph this joint on Monday afternoon to see if it still looks the same. ;-)

I had a new paved patio put down in the spring. Two of the edge slabs have come away since the hot weather started. My guess is subsiding clay underneath the cement they were embedded in. Along the edge you can clearly see a few inches have fallen away and crumbled leaving the hardcore visible. OK I';all get them put back after the heat is over and it rains, but I fear this is going to get a bit like painting the forth bridge. But you can't put your concrete down feet to make a patio and path, it would be like building a road!

I guess one fix would be to get some kind of flexible edging and put that along the line and get the gaps filled with cement to at least hold it together like a jigsaw puzzle. Brian

Yes if you have a greenhouse expect the unexpected. When I had on a propagator inside which had polycarbonate roof and sides suddenly went up in a very hot flash, and fell blackened and smoking inside the device. It seems not all polycarbonate is stable at even reasonably high temperatures. Nearly gave me a heart attack. No actual fire, but a most awful pong and what was left was very brittle. Brian

I find that the plastic gutters creak and groan and can decide to leak at the joins after a hot spell. Some of the older black ones we used to have on an outbuilding eventually melted and sagged, I think they were something coated in some kind of bithimen looking stuff.'ve had water butt lids fall to bits and the tanks to crack around the seems. Brian

On the ITV news last night, they showed Network Rail employees painting what looked like sticky whitewash all over the webs of what looked like a set of points.

Yes in them old days we used to do this with a freznell magnifying lens as kids. Also good were those old TV magnifiers filled with liquid. Another one was the mirror from a projection tv light box, bloody heavy surfaced silvered lead glass. It had to be half an inch thick to block the x rays. Those were the days of irradiated pets laying under the telly. Ahem. Brian