I have worked at Ft. Drum and here's my theory:
1) In around 1946, the whole area was "salvaged" and all structures removed
and upwards of 10,000 people removed from the area. Up to four foundries and
various other dairy related structures were removed or covered. How about:
the tracks were also torn up and the ties stockpiled. After regrading and
other improvements to the railroad, they were replaced and ended up where
they are now.
2) The fact that the foundries produced railway wheels and axles protects the
wooden ties with their magic where ever they may still lay or were recycled
into other products because they were made from magic bog iron!
3) The military would not let rail traffic on the line for a long extended
time and well face it they luke marvalus!
George J. Myers, Jr.