Radio remote control is not common here in NSW.
It is used in Tasmania to work the Railton cement train to and from Devonport.
The belt pack controller has a vigilance system built in which transmits an alarm to Train Control if the automatic response transmission is not received by the computer.
Freightcorp trialed the radio remote system for the revamped PL class DL531 units being chop-nosed 48 class.
The idea being that a PL class would be marshalled at the front and rear of trip trains working in the Sydney Metrop.
The rear unit being remotely controlled.
But, when tested on the Port Botany line near Mascot airport, rumours of a Jumbo jet incident dissuaded the use of the radio equipment.
The New Zealand rail system has utilized radio remote control for many years.
They invented the portable pack unit which can be coupled to the locomotive MU socket.
Plus, also the air.
Steve.