I think that one of the things that made Feynman great was that he was interested in ... everything, and wanted to understand everything! The precise profile of wheel-treads-- the degree to which the surface the train runs on is a segment of a cone rather than of a cylinder-- is subject to very complex and sophisticated calculations: slight changes in it are part of what's involved in, e.g., the design of high speed trains.
(Leading to a speculation: suppose, instead of wasting his talents on trivia like the space shuttle Challenger, that Feynam had been recruited to help analyze what was wrong with Amtrak's SDP40F locomotives-- would we now know what caused its derailments? (Grin!))
Railroad Forums
Feynman explains why trains stay on the tracks
- General discussion about locomotives, rolling stock, and equipment
