>Wrong! Wrong! Wrong! The wheel contour that BART uses was the result of extensive research to determine what worked best on their railroad. On BART cars you never feel the trucks hunting on the tracks. Tapered treads are NOT universal in the railroad world. Other countries, such as Australia, use treads similar to BART for the same reasons.

Wellllll, as of 2005, what used to be the NSWGRy (New South Wales Govenrment Railways) uses three or four different types of conical tread wheels. BART might use cylindrical wheels, don't know for sure, but by no means did BART originate the concept. Never forget that while BART spent big bucks (for the time) trying to re-invent rail transit at the Diablo Test Track, when the music stropped, all that wound up being "new" was the track gauge and propulsion voltage. Not even the door and seating configurations were changed from what the transit industry had been doing since WWII.

One thing is for sure, cylindrical wheels wear out and start hunting sooner than tapered tread wheels do. Amtrak and the CCJPA just recently (re)discovered this, and if it happens here it will happen in Australia (and everywhere else). One reason you probably don't feel the axles hunting is that the trucks are probably designed to accommodate it.

Besides, even cylindrical tread wheels have a conical taper around the outside edge of the tread (about 1/4 to 1/3 of the tread's width), which is de rigeur for successfully negotiating specialwork (transiting from stock rails to switch points and going through frogs).