micky writes:

Creosote and railroad ties

AIUI, creosote doesn't prevent rot, it merely deters it, that is, slows
it down or delays it (and not as well as arsenic products).

So what about railroad ties.

They seem to last for 50 or 100 years or more. Do they have to be
replaced because of rot? All of them? If not all of them, does that
mean that the creosote stopped them from rotting?

Or do they replace them all, when I'm not looking?

If they last for 100 years when used for railroad ties, how come they
don't last that long when used to support decks, etc.?

They definitely wear out, I lived near tracks and the ties are periodically
replaced.

On railroad tracks, they sit in a bed of rocks. Water runs right through
the rocks leaving the ties high and dry most of the time.

I had some creosote landscape ties on my property that rot out from
underneath.

I've got a pressure treated 2x6 on the ground now for more than 20
years without any visible rot. The board is on edge holding back
a brick pathway.

--
Dan Espen