Glossary of Terms


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3 Aspect Block
An automatic block system in which the signals can display three indications:
1) Next block section occupied.
2) Next block section clear.
3) Not less than two block sections ahead are clear

Regional
Disciplines: Train Control
3 Position Signalling
Two systems of signalling are in use in Victoria, namely two position and three position.
In three position signalling one arm or light unit may give both the home and the distant indications, and a combination of two arms on the one post may apply to any number of routes past that location. Three position signalling is therefore a system giving indications for speed control of trains and does not necessarily indicate the route to which the signal aspect applies.

Regional
Disciplines: Train Control