What I've seen, the 110 car shuttles are very efficient. Elevator has 14 hours to load them and they are normally gone shortly after they're filled.

With both 52 car and 110 car trains; you can see where the train is (or at least that car) if you know the number of just one car. The info is on the BNSF website. I'm not sure if they use satellites to track them or if the shiny new shacks that sit beside the tracks by the hot box detectors have some method for recording bar-codes on the cars as they pass.