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BTW1, did you know that the old fashioned cast iron chairs that support bullhead rail in the UK actually tilt the rails over slightly so that the top surface of the rail corresponds to the conical profile of the wheel treads?
Quote from: Geezer on 11/03/2010 19:06:00BTW1, did you know that the old fashioned cast iron chairs that support bullhead rail in the UK actually tilt the rails over slightly so that the top surface of the rail corresponds to the conical profile of the wheel treads?Yup, except I think that bullhead rail stopped being used for running lines back in the 1940/50s and only 'T' section rail is used now (you might still find it on sidings and preserved railways though). Conical wheel profiles also went 'out' in the 70/80's, and were replaced with 'worn' profiles for all high speed traffic.
I expect you guys know, but many don't, that the taper on a train wheel (the part nearer the flange has a bigger diameter than the part on the wheel facing outward) so that if the train "wanders" to one side, the change in the relative diameters of the wheels on each side (joined by a rigid axle) steers the train back. Most people think the train is kept on the track by the flange but this is not so except when going at non-optimum speeds around bends.
Sorry to be a git, but I thought that rails were welded these days.
"Ooooooo! I luff it when you talk trainy to me."
Just one thing to add: when I was in Japan and travelled on their high speed trains, my recollection (from 8-10 years ago) was that they laid their track on continuous concrete. No sleepers and ballast. This definitely applied to open-air stations, and I'm fairly sure to the whole track. I imagine this reduces maintainance as the track can't 'wander' over time - certainly not movement relative to the platform edge (there wasn't a big gap like we have in the UK).I wonder what the other implications or downsides are to mounting the track on continuous concrete...?
A combination of ballasted and slab track are used, with slab track exclusively employed on concrete bed sections such as viaducts and tunnels. Slab track is significantly more cost-effective in tunnel sections, since the lower track height reduces the cross-sectional area of the tunnel, thereby reducing construction costs by up to 30%.