I think Ethan that a freight line from fassi to hexham is a better option but with the ARTC in control of the yard at Hexham that option is highly unlikely to be taken up any time soon. Maybe if the ARTC want more frequent and faster freight rail connections to Sydney they should build their own line to Sydney from Hexham.I'd give the project up to 8 years to be approved and funded. Maybe not next election but one after, especially if the local MP's can be lobbied pretty hard. ~20km of Single track, no passing loops, intended for freight only should be cheapish enough provided no major geography in the way.
The problem is not that it couldn't be built or shouldn't be built. The problem is that the ARTC are not interested in it. They have stated on several occasions they are not interested in this and want more capacity through Broadmeadow. The NSW government in this case has been trying to get this project going but the ARTC just don't want to hear about it.
EDIT The alignment is already there as there is an old coal line that runs along the swamp and heads south westish towards minmi. You can track it from the centre of hexham yard on google maps at this link.
That's the old Stockrington colliery line, in large part its ok, but there were times especially when it was wet it would tend to sink, as the whole area is very much given the appropriate name of Hexham Swamp.
One other aspect that might hinder it is that RTA or whatever they are called these days are looking to build the missing M1 Link from around where the old line goes under the M1 across and over the highway to link on the Northern side of the Hunter River, possibly on the Eastern side of the Hexham Bridge.
The original proposal though was that going through Hexham by Rail from Dora Creek was that it would take unnecessary freight services out of the congested areas that were found from BMD - PTW, remember those days when general freight trains ran between Sydney an the Hunter area. While NCL trains could use the new line and sidings that would have been created there, it would require fresh engine changes and for them to attach to the other end, which was seen as inconvenient.