Steve X
Senior Member
Yes they could have totally trenched it with vertical walls in the middle of the street. Convert each major intersection into a bridge structure and have the platforms underneath the roadway. Any shallow construction would be built faster than a deep tube subway. The Mississauga Transitway didn't take 8 years to build. With room available, they could have temporary shifted eastbound traffic lanes 5m south and work in the middle. I don't know how challenging is it to build a shallow trench without relocating the gas line. I'm sure ML didn't want to relocate it in the first place and went with the tunnel. With a shallow subway, they definitely would not be able to for in a concourse and would need separate entrances for a side platform configuration. I don't remember what reason they gave for why a centre platform configuration is not possible. Probably cause the entrance would be stuck in the middle of the road.Trench with embankment slopes, or with vertical walls. The former requires slopes maybe 1:1 or flatter, so a a 5m deep trench requires 18m (60') of space.
The latter has a lot of earth pressure on the vertical walls, trying to push them in. Thus, it's actually cheaper to put struts across the top. Once your doing this, why not just put a roof on it and sprinkle a foot or so of topsoil along with grass. With the roof, it prevents debris from collecting in the trench, including snow, or thing being deliberately thrown.
Since we are now stuck with the tunnel option. Let's not argue why it's stupid and focus on the technical aspect.
Where would the launch and excavation shaft be located? I think it would be easier to just do two sets of TBM from west of Renforth and from west of Scarlett to and excavation shaft at Kipling. The tunnel doesn't have to align with Eglinton under the 401/427 ramp. This breaks the tunnel into ~3km each and take about 2 years to complete.
How would this connect to Renforth transitway station? The original plans called for a surface alignment right in the middle of the road passing through the traffic lights at Eg/Renfoth. I'm sure ML would hate that idea and has stated that they would operate ATO betweem Renforth and Mt Dennis station. So they'll likely would move the surface alignment onto the empty land just north of the transitway ramps.
I envision something like this. The blue is tunneled, green is at-grade and yellow is elevated (future phase). The station would be offroad opposed to in the middle of Commerce Blvd and they might as well grade separate the pedestrian walkway from the tracks like the transitway. It is the best to build a bridge to connect the LRT to the transitway. This also allows them to install fare gates to reduce fare evasion even through POP is required on the entire line. If they manage to install fare gates at every station from Laird westwards, it'll reduce the number of fare inspectors needed west of Yonge.
Even without stops at Rangoon and East Mall, they would need an emergency exit building as the tunnel between Renforth and Martin Grove is over 2km. That'll be around the 427.
With the surface alignment, there was a plan to build a stop right at Highway 27 with bus platforms on side of the highway connecting to the LRT with stairs. With a deep tunnel, that is obviously not going to work. Any connection with the 927 would have to connect to Martin Grove Station now.
I would suspect the station at Martin Grove would be very very deep to avoid both the Embridge gas substation and Mimico Creek. A bus terminal could be built here to connect to the 46, 111 as well as a branch of 927 and a possible extension of the 52G. With possibility of new routes serving south of Eglinton and short turning the 46 during low ridership times south of Eglinton. A shuttle between the airport can terminate here too as the connection to the airport might nit be built till they sort out where Union Station West would be located.
As riders shift to Line 5, ridership on express buses like 945 and 937 could terminate at Eglinton. Ridership south of Eglinton would be low. However there is barely any space to build a terminal at Kipling. They could short turn and run the buses into the Martin Grove terminal. At Islington, same story about space. It's okay, TTC didn't manage to build a bus terminal at Dufferin on both Line 2 and 5. Bus terminal at Royal York and Scarlett would not be necessary. Jane would benefit from one when ridership shifts to Line 5 although there is enough bus bays at Mt Dennis to make that redundant. A small bus loop at Jane can be sufficient.