Freight engine on Amtrak Cascades 510?

[AC4400]

I was on Sounder train this morning in King Street and saw today's Amtrak Cascades 510 with a BNSF (ES44?) freight engine at the rear.

Wondering what's happened to the P42s and F59s.

 

[Thirdrail7]

They keep running into vehicles on the tracks. Additionally, this is the time of year that BNSF requests that certain trains add engines. Sometimes, they have to help out with their own request!