Under former ALP Govt CRR (lite), similar to this proposal but I think tunnel nth to Exkka line,
Then later Anna Bligh convinced it wasn't expensive enough on borrowed money and extended it further south close to Yerrongpilly to save a few houses and thus building underground stations in low density housing areas.
All attempts to build it relied on getting +$5B from the Feds and offering $1B of money they didn't have in return. The Fed ALP saw right through this and offered lower interest rates and not a cent more and that vote of confidence from a fellow ALP govt that knew it had zero chance of surviving the next election only months away.
Then Major Newman came along, couldn't allow a good idea to get in the way of politics so they tried a few stupid options on the public to see if they would listen before settling a combined tunnel with buses with no passenger interchange to Cleveland line at Park Road and at one stage proposed closing Dutton Park until protests convinced them otherwise and cut the northern and southern terminus back to as steep as grades as possible. Still with no money to build it he pushed the start date into a 3rd term of govt (hahaha). And of course failure to proceed was automatically thrown at Tony (I hate Suburban Rail) Abbott.
Now back with ALP in Qld again and with "no asset sales" as their motto, no mining boom, no slush fund of extra revenue from real estate sales unlike their southern country parts and more debt that the Eastern Block European countries still eating away at their income stream we are back to a version of CRR Lite. To fund it they have continued the Qld govt tradition for suburban rail of triple tier govt funding (note: statement that Qld govt will need to borrow the money, surprise, not!) and added private funding into the mix just to make sure the schedule for starting in 2016 is that much harder.
Yes I'm skeptical the CRR will start in 2016.
But seriously overall on the project,
It would appear they intent to build a dedicated pair of tracks from Bowen Hills station which would see new platforms added to the an another pair of tracks on the Ekka line Corridor. Then parallel a revised Ekka line corridor including a new station at Ekka around to close to Roma Street before taking a dive for a station under Roma Street. I suspect the dive will be in the old Normanby yard where there is plenty of width and excess trackage.
The corridor from Bowen Hills to Ekka is at times on 2 tracks and questionable on how this could be expanded. Potentially this would mean a shared corridor with the new line or maybe squeeze a middle track for other users?
Maybe its the way its presented but I would have thought a new station at Ekka then just after the station dive (plenty of room in the railway corridor and swing to the left in the dive to head towards Roma Street station under Spring Hill.
Rising at Dutton Park is fine, but from Dutton Park to Salisbury there will be a need for four NG tracks to cater for future traffic needs and potentially the future Green Bank line.
I suspect this plan retains the GC traffic on the bridge and Beenleigh line traffic will use the tunnel and feed a northern line?