The Geelong line was VR's busiest country line and therefore was equipped with ATC to allow closely spaced follow on moves. ATC came to Little River in 1928, double line was extended from Werribee to Little River in 1970 but did not continue on to Corio until 1981. In 1972 the last of the 2 position signals at Little River were replaced by 3 position signals
The major change that this diagram shows is the extension to #2 road to allow longer trains to "cross"

In this diagram Lara was another oasis of 2 position semaphore signals in the middle of 3 position ATC. Lara lost its last 2 position signals in 1973.

In this diagram, Corio is almost all 3 position signals, the double line ATC from Nth Geelong having reached Lara in 1959.