Thanks for your input Drayrr. I can't understand, however, how the point of wheel tread/rail contact can be one square inch if the rail or wheel is not plasticised. It would seem to me, that an area of wheel interface with a rail would be smaller than the area of touching a wall with a very thin tapered blade which came to an extremely fine point (microscopic), as the realities of geometry do not allow true straight and true round to interface at more than an infinitesimal amount at the point of highest contact. Modern rail is curved, so this even tends to disallow perpendicular, as well as lateral abutting, unless the wheel profile exactly contours to the rail. Which brings about some very interesting ideas relative to how strong rail and wheel construction has to be in order to not deflect under these loads. The standard grooved-rail and grooved-wheel with mucho miles on it is probably an attempt by which this coupling attempts to enlargen this small contact area, and in doing so, perhaps increases contact perpendicular to the wheel only. Flat spots would probably enlarge the contact area in both directions. I guess I know why trolleys blow sand during winter on rail and why wheels spin on starts.(Think of this the next time you're doing 125 on Acela !) Thanks again.
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