Thanks guys!
My reason for asking is I'm in the process of converting all my 3-rail steamers to Battery-Power Remote Control and have removed the middle "training wheels" on the engines, but kept the big flanges on the drivers and trucks. I no longer need the middle rail.
I can remove the middle rail from my layout, but I was thinking of redoing the 072 and 054 curves with 090 and 072 and #5 switches. If I can't find switches that will work with the big flanges, I'll just live with them for now. It'll still be 2-rail (and remind me of the old HO big flanged equipment).
Maybe for now I'll leave the track as is and run the BPRC steamers for a while. I also have 7 diesels (PS2 and TMCC) that can easily run with the steam locos, as long as I keep the middle rail and wiring. But my goal is to go all BPRC (maybe even sell off my 3-rail diesel roster).