Good one Jon!!

Rolling 600 ton train + sparks + Corrugation = Deep Rabbit Hole dive (you knew we would) ⊥ possible train wreck ∴ how the guy looks in the 1912 Montreal picture ⊃ Good, fun learning Or a headache of train wreck proportions.

Enjoyed a shallow dive (40min.) until the primary variables and sub variables made my left eye jitter. Franks link was one of about 300 white papers I found and pretty good but no date. Found this EU site from a commissioned study from 06' and danger/cost related issues. Can't imagine the maintenance on subways in NY. And how often do they have to change the Grinding wheels?

Quite a scorching train ride. Thanks Jon!

PJ