Why do continuous railines do they not buckle in the heat.?

I am told by a railway engineer that there are two factors here.





1.....The lines are not continuous. The lengths are huge, but every now and then there is a joint.





2.....When the continuous lengths are laid they are expanded using a sort of gigantic blowtorch affair. They are then clamped into position. The rails try to contract to normal length but can't - they remain in tension. So when the weather gets warm all that happens is that the rails expand a bit and the tension is reduced - still no buckling.





Occasionally the job isn't done right, and in extremely hot weather there is then some deformation.

Why do continuous railines do they not buckle in the heat.?
The rail lengths are about a mile long. They're made up of shorter lengths (about 200 metres or so these days) which are welded together then the whole lot is put under tension. The rails are kept under tension by the weight of the sleepers held by the ballast.





At the end of each length the rail is cut in a type of diagonal. The diagonal end of the abutting rail is placed alongside it. Lay your hands palm to palm and see how your fingers of each hand overlap to get a rough idea (don't interlace them) and imagine that your forearms are lengths of contiuous rail. Remember when you look at it that the train will run over the narrow edge of the joint.


There is a gap of about 2cm between the diagonal cut edges (your fingers) but no "straight across" gap like there used to be with old fashioned jointed rail (with fishplates).





Thus the train wheel is always in contact with one or the other rail head. You don't feel the joint at all from the train.


When the rails expand the cut diagonal ends slide past each other and the gap closes a bit.





In extreme heat the rails can buckle but, despite the sensationalist ravings of the common press, this is very very rare. If it does happen it is not dangerous in 99.9999% of cases, but speed limits are imposed to stop the trains and their passengers getting shaken to bits.





You can sometimes see these joints in stations. They're marked by two short lengths of rail bolted lenghtways between the running lines.
Reply:The steel is too strong. There are track watchers that look for stuff like that but the heat itself doesn't bother then cause the ties mount them properly.
Reply:Because they have expansion gaps built in to allow for temperature and climatic changes .
Reply:(1) I think they do (very occasionally). (2) they are not actually continuous (see answers above on expansion joints).





I wouldn't worry about it if you are in the UK, with the summer we've been having...
Reply:Each rail is a certain length, say 10 metres or so, when the rails are joined to each other they use a connection plate called a fishplate and they leave a gap between the rails of up to an inch to allow for expansion in heat to prevent the rails buckling this is why you hear the clickety click sound when train is driving along
Reply:They have joints which allow for expansion/contraction.
Reply:Different materials from what used to be, when you had frequent expansion joints. The joints still exist, but much less frequently.
Reply:They do expand with heat, if you notice rails are cut into lengths for handling and when they are put down they leave gaps for this expanding and contraction in hot and cold temps.
Reply:The rails are nearly continuous and they are clamped into position after being heated so they are under tension in normal use then hot weather only relieves the stress, any over cooking is usually held in place by the sleepers but occasionally the heat is too extreme and the rails go ape but very very rare.
Reply:Because at some point there is a diagonal joint in the rails designed to allow for heat expansion, mind last year there was rather a few places in the UK where temporary speed restrictions where in place because of the rail head conditions.



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