> That said, two things come into play: (1) the contract SP and Amtrak had in effect at the time covering 'Act of God' service interruptions, and (2) WP's agreement for reimbursement of costs for hosting foreign line trains, including reimbursement for the cost of providing pilot engineers, conductor pilots (if used) and/or Road Foreman of Engines or Trainmasters (if used). If no pilots were used, those costs would be against the cost of using regular freight railroad crews.

An attempt to explain things a little more clearly:

The WP and SP had mutual agreements regarding detours caused by "acts of God". Although I don't know specific details, these involved the monetary compensation for use of the tracks and for pilots (or entire crews if necessary). However, the "fees" weren't as punitive as you would expect between the two RRs because if one of the two charged exhorbitant fees for rerouting, it could backfire when it needed to reroute on the other.

As long as the WP was the WP, no Amtrak train ever operated on it because it didn't want to become obligated to run Atk trains on its rails (ISTR there was an exception to this shortly before the UP's takeover of the WP). The UP was not so Amtrak-unfriendly, so AMtrak trains detouring on the former WP became more commonplace.