What voltages do Australian rail signalling systems use?

AS 7703, the national railway signalling power supply standard, sets the conventions: 50 V DC for signalling logic and interlockings, 24 V DC for electronic equipment, 12–15 V DC for level crossing and legacy equipment, and 110/120 V AC for main distribution. ARTC’s level crossing standard specifies 12 V and/or 18 V nominal DC systems with 240 V single-phase AC. Individual rail infrastructure managers add their own network standards on top, so the governing document for any given site is the RIM’s functional specification, not the national standard alone.