Keep in mind
many conceptual RER graphics uses variations of the Stadler KISS pictogram which is a bilevel EMU.
It is one of the candidate trains proposed for RER, amongst many,
It even has a dual-height door option, which CalTrain ordered. It is a wide doubledoor for all four sets per coach, wider than Montreal AMT's Bombarder MultiLevel.
- Order mainly low door option for core electrified GO routes (serves GO platforms)
- Order at least 30-40 coaches with dual level doors (serves GO & UPX platforms) with baggage racks.
Then plenty of UPX spares, which can also run on the rest of the RER network when not used for UPX.
Fleet commonalty opportunity?
This proposed GO EMU has a dual height door option too, that can serve UPX platforms.
Basically, the Stadler KISS train, with the optional high door option. Get some with, get some withut, and gain fleet commonalty.
Slightly longer boarding is mostly nonissue due to long dwelling at Pearson and Union (the high traffic stations) unlike middle sections of double decker routes (e.g. Sydney, France). The UPX boarding and disembarkation pattern will adapt well to these bilevels.
Opportunities could include making one coach for strictly airport passengers only at Union, or encouraging one deck to be airport travellers and the other deck to regular commuters.
Accessibility would be wheelchair areas at the midlevel floors. Most baggage racks could be at the midlevel areas, to reduce baggage hassle of lifting bags up/down stairs.
And since low floor doors will not be used for UPX service, additional overflow foldable baggage shelves could unfold in front of low level doors! (Only when the specific trainset is currently in UPX service mode rather than RER mode)
Huge fleet commonalty opportunity if it can work out?