Stupid questions about standard gauge track

Lionel, Flyer, and IVES track all are interchangeable size wise; I believe Dorfan is, too.  There are minor differences among batches, but they are all pretty much compatible EXCEPT for early Lionel split-pin tracks that have half a pin in the center on one piece and a matching half on the other.  The full pins on the outer rails alternate.  I think the result was a little too delicate, but it had the advantage of not having to pull pins to reverse curves.

VERY early on, Lionel made some 36" diameter curves.  Very hard to find.  Reflects the early emphasis on trolleys.  No wider among these manufacturers in the Early and Classic Periods.

Boucher track is rails mounted on wooden ties on wooden roadbed.  The gauge is the same, but it is not compatible with the others.  There were two diameters:  50" & 80" IIRC.

I'm sure others who are more knowledgeable will chime in to add-to or correct me where necessary.

@palallin posted:

...early Lionel split-pin tracks that have half a pin in the center on one piece and a matching half on the other...  ...had the advantage of not having to pull pins to reverse curves.

Ahhh... the genesis of the FasTrack design.

Tubular track curves of other diameters are still available as NOS from various forum sponsors.  A great source for currently-manufactured high quality standard gauge track is USA Track (owned and operated by forum member and passionate standard gauger @SGMA1) - website is https://standardgaugetrack.com/.