Up in front was a big BNSF locomotive, followed by two Gennies and then the rest of the consist. It looked like one of the Gennies wasn't running (I didn't see exhaust coming out of the top), so i assume that there was a rescue involved.
You can see it hooked up to the Gennie at platform 6, at the left.
I would guess that train engineers are like airplane pilots and are qualified on specific equipment. So does that mean a BNSF engineer has to drive the big orange locomotive? And how does Amtrak call for help? Presumably on a long route like the Southwest Chief, there can be quite a delay if the power goes out in one of the regular locomotives. I imagine the rescue locomotive chugging along for hours to stage the rescue, but that may simply be imagination run amok.
Incidentally, you can see in the picture below how close the trains are on tracks 12 and 13. You can also see that the Pacific Surfliner is just as tall as the long distance cars. Interestingly, however, the Gennies are shorter. One of the conductors told me that east of Chicago, the tunnels are lower (hence the single level cars, like the Amfleet/Horizon trainset that we suffer on one consist on the Surfliner). The Gennie can fit into them but the F59s and double decker cars cannot.