An unusual sight... on a 3 hour stop aboard a southbound Amtrak somewhere in South Carolina or Georgia on the CSX north-south mainline, May 2006. The FRA unit is sitting right on the main feeder switch of a regional classification yard. No freights passed north nor south during that time, despite the hourly passings I saw before and after this extra long (and unscheduled) stop. And the FRA unit didn't show any signs of moving off the classification "Y" during that time.