Comment 1). Nine-car platforms south of Glen Iris make perfect sense in the context of the Burswood Stadium and intensivive post-event traffic. The Thornlie - Glen Iris connection is of course key to that. At some point, Transperth/PTA will need to bite the bullet of SDO (Selective Door Opening) as being adopted in Britain as train lengths are increased to cope with demand. That would allow 9-car trains to work to 150m platforms. The system used in Scotland has the "all-stations" cars at the leading end, and advises passengers about those stations which require them to be "up front."
As regards the Canning Vale line, I envisage the station at Market City to be a busy bus interchange. I also envisage a deviation into a new rail-air interchange terminal at Jandakot Airport, which in turn would seed the relocation of a lot of regional resource industry flights from be served at Perth Airport's western precinct.
Comment 2). Extensions are also likely on the other three lines. I would expect Armadale to Cardup Brook (southern end of Byford, adjoining Cardup); Midland to Stratton, and then via Upper Swan to The Vines and Ellenbrook (a poor Man's Ellenbrook line!); and Fremantle to Yangebup via Port Coogee. Later, I would expect East Guildford via Hazelmere and High Wycombe to Perth Airport Eastern Precinct (International Terminal). Initial services to Stratton and PIA would not be frequent, maybe half-hourly to fit in with the freight traffic. Only once dedicated tracks, or in the case of the Airport, a dedicated route is implemented can frequencies be raised.
Comment 3). A semi-fast service to Bunbury using dual mode or diesel-hybrid stock could be envisaged. This would require the line to be built either along the Forrest Hwy alignment, or along the Mandurah Bypass/Old Coast Rd alignment. Running times would be more like 1hr 40mins inland, and 1hr 50mins along Old Coast Rd. Inland route serve Perth-Bunbury only, but the Old Coast Rd route would allow Mandurah station to be included. The foothills route via Armadale/Pinjarra cannot really be accelerated due to the freight traffic. However, the mode of operation seems to me to be very time consuming, with protracted dwell times and ridiculous platform occupancy duration. I would say that 20 mins could easily be cut out of the running time by streamlining boarding arrangements, but only if the paths were there - and the latter is the crunch on a freight railway.
DW in Devonport