About the only detours you'll see anymore on Amtrak are pre-planned "programmed" detours, planned months or weeks in advance for trackwork or other reasons. The Starlight detours over Tehachapi are an example of this.

Last minute, spur-of-the-moment detours due to derailments, etc., decisions of which have to be made quickly on the local level are pretty much a thing of the past. Calling out buses is easier and looks better for the "bottom line." Amtrak loses less money operating buses than it does running trains. What a deal!