I think they will probably use standard subway cars just like Yonge/Bloor but have overhead power supply like Cleveland and many other Metro systems on regular rail track so the average rider sees it just as another Toronto subway. I can see Tory wanting to take up some of the UPX line and god knows most in Toronto would support that. Tory will want this seen as a DRL subway without the DRL price which it effectively is.
Federal regulations won't in a million-billion years ever allow Toronto Rocket style cars on mainline rail. It's a safety risk. TRs have no crash protection.
When ML did their study and found that the ST would have very little i9mpact on the crowding at Y&B they did so using the model that the train would run every 15 minutes and were unsure about the fare integration.. There is a HUGE difference between 15 minute service on an extra fare line and 5 minute service using your TTC ticket in terms of riders they will create...............in terms of ridership potential they are not even comparable
Metrolinx used between 5 and 10 minute frequencies to evaluate the RER+ option on Yonge Line crowding, which is exactly the same service plan described in Moore's article. East of Yonge (the relevant potion), it included stations at Unilever, Queen East, Main Street, St. Clair East, Kennedy, Sheppard and Steeles on the Stouffville Line and stations on John Street, Highway 401 and near Finch on the Richmond Hill Line. This differs from SmartTrack in that SmartTrack will have fewer station, as it won't operate on the Richmond Hill Corridor.
The results of the evaluation were that it diverted 400 people from Yonge Line at peak hour.
Unfortunately it's not clear in the Technical Summary if they used GO fares or TTC fares, or if fares were considered at all. If they assumed TTC fares, or didn't bring fares into account, we can expect SmartTrack to have a similar, if not less effect on Yonge Line ridership than RER+. If they assumed GO fares, then the effect on Yonge Line ridership would be an order of magnitude higher. It's conceivable that it could reduce Yonge Line ridership by 4,000 pphpd, which would delay the need for the Relief Line by 9 years.
I think Tory and the TTC will want to differentiate the ST subway from RER/GO which would also be easier for the travelling public to know what service is standard TTC and others that require an extra fare.
The only planning justification for this would be if ridership were so high that they can't fit on the RER EMUs. Otherwise we'd essentially be spending billions for branding purposes.
Given SmartTrack's striking similarities to RER's service plans, I'd expect SmartTrack to use RER EMUs. Essentially it would work by having everyone using GO RER between Kennedy and Mt. Dennis pay TTC fare.