The line was dismantled (at least, the bit that goes under the Princes Freeway) early last year (2002) / late 2001.
The line signed "Briquette line" is not the SECV line. It branches off at Morwell Yard/station and goes to the briquette factory (Energy Brix), where it stops. According to some old maps, it used to go around to the eastern side of Hazelwood Power Station.
The SECV narrow gauge went from Yallourn to Hazelwood Power Station / Morwell Open Cut and this is the one that went under the freeway. It doesn't join up with the briquette line.
The Mirboo North railway (not tramway) line branched off from Morwell Station in the up direction (i.e. backwards, so trains from Melbourne had to turn around) and went down the middle of what is now Maryvale Ct. This is the reason that the median strip down the middle of the road is so large. The last goods train ran in 1974 (?) and pass in 1971 (?) and the Morwell Open cut has since expanded over part of the alignment.
In Moe: there were three branch lines from Moe.
1. The one that you can see the alignment of under the bridge is the old line to Yallourn power station, broad gauge. It was electrified and E and L class electric locos ran on this line (?).
2. The Erica/Walhalla line was narrow gauge and the alignment (I think) ran roughly between where Moore St and Saviges Rd are now. There is a good site on this railway: http://www.netspace.net.au/~wrussell/narrow/walhalla.htm
3. The Thorpdale line branched off halfway along Narracan Drive between Moe and Newborough and basically followed the Narracan Creek to Narracan and Thorpdale.
If you want maps, there are plenty of maps on the net that have old lines on them. If you go to the Coles website (I'm not advertising
), go to Store Locations under About Coles, and use the map feaure they have (search for Morwell). The map is slightly (!) outdated, so it still has some of the old lines on it.