While at work this week, I came across a 1954 MMBW report, with planning maps. Looking at the maps, I came across 5 proposed-but-never-built rail lines. Details are as follows (references are from Melways):
* Mornington direct.
This line branched off around 102 D3, and then headed south to Sweetwater Creek, west to Humphries Road, and then south again parallel to the Nepean Hwy (map coverage ended around 101 H11).
Stations were to be around 102 D6 and 101 J8.
I exepct a bit of tunnelling would have been required.
This line branched off around 77 D7, and then curved across to Spring Street, headed south parallel to this street, and George Street; then curving across to run alongside where Balcombe Park Lane and Gareth Avenue now are.
Stations were to be around 77 C11, 86 B2, 86 C4, and the terminus at 86 C7.
* Darebin Creek (I have already seen this somewhere else previously).
This line branched off near Alphington, around 31 C10. It then headed north not far west of Darebin Creek, before finishing at East Reservoir.
Stations were to be at 31 B7, 31 A4, 31 B2, 19 B11 (close to Northland), 19 B8, and the terminus at 19 A6.
* Laverton North (I've also seen this line on 1977 MMBW maps a few years back).
This line branched off at Braybrook where the current bridge over Sunshine Road is. It headed west, with another line leading in from the Sunshine-Newport line. Next, it crossed Kororoit Creek and headed almost due-southwest, crossed Fitzgerlad Road, and ran down the west side of that and where Princes Freeway now is, to meet the main line just on the up side of Laverton.
A branch came off just after Kororoit creek, to run west alongside where Learmonth Cresecent, Felstead Avenue, etc, now are, before terminating where the Western Ring Road now is.
Had this line been built, the operators could no doubt have been able to get a lot of traffic from this now rapidly-growing industrial area.
* Fishermans Bend
This line was a 'double balloon loop' setup. It branched off around where Graham station was, and headed northwest to split with lines on either side of the current West Gate Freeway, coming to a balloon loop with its western end at the western end of the current West Gate Park.