I was thinking about the Sheppard West subway and figured there must be a way of doing it to provide more benefit. I am sure I have seen parts of this before, but I will consolidate it into one plan. Essentially, the Sheppard subway would be interlined with the Spadina line at the (existing) Downsview station, alternating going north and south. Here is the resulting TTC map (excuse the poor graphics).
So we have 4 lines (actually 3, but I gave the short-turn one its own name) operating and the YUS and Spadina lines. At peak, the trains have the following frequencies:
- Yonge-University-Vaughan (yellow) = 4 minutes
- Yonge-University-Downsview (red) = 8 minutes
- Sheppard-University-Yonge (pink) = 8 minutes
- Sheppard-Vaughan (blue) = 8 minutes
Each train would be colour coded so that passenger know which direction there train would go (in addition to the sign on the front of the train) - even the short turn train has a colour coding so that passengers will not complain about being on a train the short-turns.
This means that:
- On Sheppard, trains are every 4 minutes going eastbound and then every 8 minutes going west then north and every 8 minutes going west then south - (i.e. a train every 4 minutes).
- On the Spadina Extension, 3 trains every 8 minutes (gaps of 2, 2, 4 minutes) go northbound, while trains go every 4 minutes south along the existing YUS and trains are every 8 minutes to go south then east.
- On the existing portion of the YUS, 3 trains are every 8 minutes go towards Downsview (2 of which continue to Vaughan) and 1 train every 8 minutes go towards Downsview then east. The frequency towards Finch is 2 minutes.
To accomplish this, there would be a Downsview Station on the Sheppard line. The Sheppard line would go under the Spadina line and then curve down to join the Spadina line north of Wilson (with the northbound to eastbound ramp going over the Spadina line) and also the Sheppard line would go north and join the Spadina line south of Sheppard West (the one with the GO hub) (with the westbound to northbound ramp going over the Spadina line and joining in from the north). (I do show the option of the tracks crossing here, but with farther thought, I think it is worth separating the tracks here). There would be one intersection where the westbound to southbound ramp crosses the southbound to eastbound ramp - this would be acceptable since the frequency on these ramps is 8 minutes for each movement.
Here it is graphically (again, not the greatest drawing skills)
This interlining proposal differs from the Lower Bay Wye that was used decades ago since the frequency on all sides of the Wye are not the same. The Sheppard westbound to southbound train could arrive early to Downsview and have a planned wait to ensure that it joins the Spadina line southbound at the correct point in time - since it is maintaining the frequency southbound that is critical.
The curves to make up these ramps are about 350m radius, about the same (actually a bit more gradual) as the Spadina curve from Allen to Sheppard West. However, they are less critical since the train frequency on these ramps is not as critical and they could be taken at a slower speed - the only important thing is that the trains be on time to head southbound.
There would be next to no transfers between the two Downsview Stations (the Spadina one and the Sheppard one) due to the interlining - so they could be separted by some distance so that the new Downsview Station would not have to be built under the existing station - they would be close enough to share the bus terminal though. The station is shown at Faywood, although it may not be needed since the Downsvew Station would extend well East of Dufferin. There would be twin tunnels going under Spadina at Sheppard - which would add some complexities - but the remaining ramps would go above the existing Spadina line, plus all the construction would involve simple excavation and is to the west of Allen road (and south of Sheppard) with minimal to no disruption to traffic. Construction does get a bit close to the runway, which may be a problem.
The last thing is that all trains would consist of 8 cars, except for the Sheppard-Vaughan subway (blue) which would consist of 4 cars. For all stations at Bloor and north, the front of the trains would line up with the end of the platform and the last car, plus perhaps one door from the 7th car, would not line up with the platform and would not open. (When on the Sheppard line, the last 4 cars would not line up at the station and would not have doors open). For all stations south of Bloor, the back of the train would line up with the end of the platform and the first car, plus perhaps one door from the 2nd car, would not line up this the station and would not open. Some smart commuters would enter the 7th car north of Bloor and walk-through to the 8th car so they could disembark from the last car south of Bloor. These 8 car trains would have 30% more capacity than the current 6 car trains. (As stations get busier, the platforms on select high-volume stations could be increased so that the full 8 car train would fit - I am thinking Yonge-Bloor and Union where adding some extra platform length is easier than adding a whole new platform)
