Firstly, there is a mechanism to drive the points between Normal and Reverse and vice versa.
Secondly, there is some apparatus to check that the switches are set and locked correctly and safely.
If the turnout is not set and locked correctly, then signal(s) won't clear.
Now a normal turnout has two blades, which are driven and locked separately.
A catchpoint may have but one blade, and half of the gear on the point motor is unused.
However a dual gauge turnout has three [or even five] blades, [which may exceed the capability of a single double sided point motor. So how is the drive and detection done? See next post by @KRviator for some answers.
There are a lot of dual gauge turnouts between Perth and Northam in WA. Can someone check? Does anyone know for sure?
Edited 6 times. [Some original text marked as superscripts.]