28-engine consist?!?

I was looking at Virtual Railfan's Youtube channel and saw a crazy 28-engine consist. Lead engine is BNSF 9034, and they're all BNSF engines. Wha... anyone know about this consist? Any reason why they're hauling 28 engines? I'm assuming only a few are pulling the load and the rest are going to a shop or something.

Here's the video with the date/time stamps.

Comments seem to indicate that they're leaders headed back to GE.

4470 - 4590 loco number group. Definitely some ferry to where ?

Twenty-eight locomotives but only one engine.