I wonder if the railroads came back to UPS with a deal. UPS did not want to leave the rails, it was oil that was slowing schedules. UPS was paying the railroads a premium for guaranteed delivery windows, most trains had a delivery time and a 4 hour window to make the guarantee.
Heavy oil volume across the BNSF northern mainline caused massive disruptions to schedules, trains were frequently days late, which should have meant that BNSF paid on the service failure, which I am betting covered any service claims from customers.
Those oil trains were handed off to the NS (primarily) in Chicago, which caused service disruptions on their lines.
Oil shipments are down now. Who knows for how long, but I am starting to see some UPS trailers on trains again. Not nearly as many as in the past, but maybe the railroads are starting to realize that they cannot afford to lose UPS. It was not that long ago that it terms of dollars spent, UPS was the largest customer of the Santa Fe and then the BNSF.