I agree with your assessment, but I don't see much value in the "mid"-western sextup, nor even the amplification from Hurstville to Sutherland. These projects are about traffic class delineation rather than capacity, and the transit time saving of each are marginal at best. Quadding Hurstville to Mortdale makes a tiny bit of sense, if Cronulla becomes an interuban route .
Where the real problem with the network is - and always has been, is Strathfield to Redfern. ATM, the "solution" is to sacrifice transit time for Liverpool to achieve sectorisation and operational simplicity.
IMHO, station rationalisation on the corridor would help a lot. Rationalise Lewisham, Pewtersham and Stanmore to just Petersham (with a decent connecting walkway). Close Macdonaldtown and replace it with an Eastern Concourse at Newtown Station.
Have Burwood, Ashfield and Newtown as "major" stops (all Secetor 2 trains stop there). Croydon, Summer Hill and Pewishmore served by 1 of the 4 patterns on the route, so all (well 3/4) trains make 4 stops between Strathfield and Redfern (limiting the transit penalty to 8 minutes).
I also think a Western Express with 2 CBD stations (but perhaps only 1 at either Wynygaroo or Townyard), and 240m platforms to allow 10 and 12 car trains on the Western and Richmond lines.
With respect djf, I totally disagree with your analysis, particularly with regard to your statement that you don't see much value in the "mid"- western sextup. I'd regard this as being the most critical factor in improving the performance on this section of the Western Line corridor. It's a myth that Metro West will resolve the constricted capacity on this sector.
For starters, you have 3 track pairs merging into 2 at Granville and another from the proposed reinstatement of the Liverpool via Regents Park services. It already restricts the full utilisation of Platforms 3 & 4 at Parramatta, which only have 6tph in the peak, when they could potentially be quadruple that with further track amplification and the signalling upgrade, as well as completely segregating T1 and T2. Platforms 1 & 2 at Parramatta are maxed out at 20tph, including BM Intercity. It beggars belief how you can be so dismissive of this fact.
Similarly, while the quad extension from Hurstville to Sutherland doesn't have the same priority, it will eventually be needed. It is anticipated that the maximum frequency between Hurstville and Sutherland on the existing single track pair will be 18tph with a mixed stopping pattern. That restricts the number of trains, both suburban and intercity, which could run on the quad track from the CBD to Hurstville. The quad track extension will enable all stations and express services to be separated as they currently are on sections of the Northern, Western and East Hills Lines, increasing overall capacity.
The Main Line tracks on the Strathfield to Redfern sector are currently underutilised, with only 12tph in the peak, when they could be double that with the signalling upgrade and diversion of more suburban services into Sydney Terminal. The Sydney Terminal Area Reconfiguration Project implies that this is the intention, although admittedly not ideal, forcing interchange to reach other CBD destinations.
As I alluded to earlier, any sextuplication of the Western Line corridor should extend into the CBD via a new express tunnel, which would be relatively inexpensive without any intermediate stations. That would allow all Western Line services to be diverted to the new link and also allow the longer distance T2 services via Granville and Regents Park to share the express Suburban tracks with T9 through the CBD across the Harbour Bridge. It may not strictly conform with sectorisation, but so what if it separates express and all stations services through the Inner West.
Good luck with eliminating stations on the Inner West Line. It's totally unrealistic, when it could be upgraded to a high frequency 'turn up and go' service at 24tph, whether SD or DD, if there was the will to amplify the Strathfield to CBD corridor.
A Western Express service into the CBD still warrants consideration. It could initially branch from the Main at Eveleigh as originally proposed, with new underground stations at Redfern, Central, Town Hall West and Wynyard (under Platforms 3 & 4 and the intermediate station concourse}. In the longer term, the suggested express tunnel from Strathfield could link with it.
With the current Waratah fleet limited to indivisable 8 car sets, it's not practicable to increase suburban services to 10 or 12 car sets, so there is no point in increasing platform lengths to 240m. The 10 car NIF sets will all run into Sydney Terminal.