Train Delays - It's a bit Warm
Discussion
WTAF! I have been to the south of France when it was hot and the trains still worked.
Has someone specified overhead lines that work OK to 36 degrees but fall down at 37?
In my industry you specified a standard that gave a range of temperatures stuff should work at eg valves Specified to operate between -17 C and 120 C.
What is the spec with overhead lines? why do they fail when it is a bit hot and why did the guy warning of future delays due to the (BBC agenda) frickin climate!!
Shock Horror - It's a bit hot in the Summer, and although not the hottest ever, but the system can't cope.
Has someone specified overhead lines that work OK to 36 degrees but fall down at 37?
In my industry you specified a standard that gave a range of temperatures stuff should work at eg valves Specified to operate between -17 C and 120 C.
What is the spec with overhead lines? why do they fail when it is a bit hot and why did the guy warning of future delays due to the (BBC agenda) frickin climate!!
Shock Horror - It's a bit hot in the Summer, and although not the hottest ever, but the system can't cope.
Scotty2 said:
WTAF! I have been to the south of France when it was hot and the trains still worked.
Has someone specified overhead lines that work OK to 36 degrees but fall down at 37?
In my industry you specified a standard that gave a range of temperatures stuff should work at eg valves Specified to operate between -17 C and 120 C.
What is the spec with overhead lines? why do they fail when it is a bit hot and why did the guy warning of future delays due to the (BBC agenda) frickin climate!!
Shock Horror - It's a bit hot in the Summer, and although not the hottest ever, but the system can't cope.
er, i think you'll find it's a bit hotter a bit more often in the south of france!Has someone specified overhead lines that work OK to 36 degrees but fall down at 37?
In my industry you specified a standard that gave a range of temperatures stuff should work at eg valves Specified to operate between -17 C and 120 C.
What is the spec with overhead lines? why do they fail when it is a bit hot and why did the guy warning of future delays due to the (BBC agenda) frickin climate!!
Shock Horror - It's a bit hot in the Summer, and although not the hottest ever, but the system can't cope.
That is the point, everything is a compromise between performance and cost. We could, today, stop all trains running for a year, and completely upgrade our entire network to work at 50 degC continuously. But the cost and delays from doing so would be un-tenable. Just like we don't design a car to be able to be crashed at it's maximum speed and the occupants survive, despite the car being able to go that fast!
Go back to the South of France when it’s -10 degrees centigrade for a few days (how the f
k do you get the ‘degrees’ symbol on an iPad?) and see how they perform. Cracked rails galore!
Simple fact is we tend to use Continuous welded rail which is pre-stressed to work within a defined temperature range that tends to cover 99% of our weather. Outside these limits and restrictions have to be put in. Raise the higher temp limit and you risk cracked rails in winter and conversely, have a lower temp limit to cope with a harsh winter and you risk buckled rails in summer. Notice how French trains are struggling in the north and working ok in the south? Different levels of prestressing according to what weather they generally expect to see.
Plus you have st like a greater chance of line side fires, sagging wires and whatnot which can cause additional problems.
k do you get the ‘degrees’ symbol on an iPad?) and see how they perform. Cracked rails galore!Simple fact is we tend to use Continuous welded rail which is pre-stressed to work within a defined temperature range that tends to cover 99% of our weather. Outside these limits and restrictions have to be put in. Raise the higher temp limit and you risk cracked rails in winter and conversely, have a lower temp limit to cope with a harsh winter and you risk buckled rails in summer. Notice how French trains are struggling in the north and working ok in the south? Different levels of prestressing according to what weather they generally expect to see.
Plus you have s
t like a greater chance of line side fires, sagging wires and whatnot which can cause additional problems.Riley Blue said:
matchmaker said:
85Carrera said:
Train delays were due to concerns about tracks buckling.
So fk all to do with overhead lines.
Wrong. A lot of OLE problems.So f
k all to do with overhead lines.Then when I finally picked up wife’s new car I got stuck behind a bicycle race for ten miles.
On the other hand, on thursday took the train Bristol to Paddington and back again. Way out was no trouble. Was prepared for major delays on the way back at 5pm; we left on time but had a 30 min delay just before Reading (due to a train fault, not track) but recovered some of that by the time we made Bristol. The trains remained nice and cool throughout. Overall can't really complain.
Cantaloupe said:
I must say I thought that expansion of overhead lines due to heat was built into the system via pulleys and counterweights,
i.e. no matter the temp the wires remained at a set tension.
That is indeed the idea. Except when the weights are resting on the ground because the wires have stretched so much. Or like at St Pancras the other day when the wire snapped and started a fire. You don't really want a 25,000 volt wire flapping about anywhere near trains, humans...anything you don't want burning, in facti.e. no matter the temp the wires remained at a set tension.
I had a mate derail not that many years ago. Track workers had re-laid a section and forgotten ...or it was never designed in... any expansion joints. First hot day of the year, ol' Bob* trundles round the corner and the rails had gone like a rollercoaster. He derailed the first coach and thought he was going all the way down the embankment onto the road below.
It's a thing*not his real name
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