The story I heard was the eastbound Empire Builder got stopped by a BNSF derailment. Passengers were bussed and the empty equipment was detoured to the twin cities. Meanwhile, the westbound that was supposed to use this equipment was substituted with single level cars to the twin cities and transferred across to the empty eastbound that was turned to become the westbound. I never heard where the single level equipment was going from there. Maybe it was on the westbound Builder?