The former Rock Island/Southern Pacific route is single track with passing sidings since it was built.
When the "Golden State" passenger train ran across this route,RI/SP installed automatic block signals(ABS)
When RI went "belly up" and the real property was sold off,SSW(Cotton Belt),a part of SP,bought the route,
and rebuilt the route,retaining the ABS system,SSW was "folded" in to SP,then the UP-SP merger.
UP uses the Kansas City-El Paso route as a part of it's "Southern Transcon" to Los Angeles,
and has installed CTC across the entire route,along with extending key sidings.
There are 2 other legs on the "Southern Transcon",El Paso-New Orleans and Serria Blanca-Memphis.
All US built locomotives have some type of "Alertor" system that requires a "responce" from the crew in the cab.
UP uses Cab Signals on the "Central Trancon"(aka,"Overland Route) Omaha-Ogden.
"Crew rest" and "fatigue" issues are coming to the forefront nowadays,along with the term
"Safety Sensitive Fuctions" This will open a can of "worms" in "Hours Of Service" issues.
They are different for Pilots,Truckers,and Train crews,and might not be apportate in this thread.
The Land of Enchantment is not Flyover country!