Digging the Eglinton Crosstown West Extension​

From https://www.metrolinx.com/en/discover/digging-the-eglinton-crosstown-west-extension?utm_source=sfmc&utm_medium=email&utm_campaign=ECWE_MonthlyNewsletter_EN_20250703&utm_term=Intro+Block+EN+-+Digging+the+ECWE&utm_id=982926&sfmc_id=121318871

The extension will make the Eglinton Crosstown LRT (to be known as Line 5 Eglinton when it opens) another expansive east-west rapid transit line for the Greater Toronto Area (GTA), connecting commuters all the way from Scarborough, through midtown Toronto and into Mississauga. The project will add seven new stations over nine kilometers to Line 5 Eglinton’s 25 stations and stops.

Unlike the 6.3-kilometre stretch of tunnels on the western end of the line which were excavated using tunnel boring machines, the 500-metre twin tunnels under construction are being built using the sequential excavation method, also referred to as SEM. This is a method often used for smaller sections of tunnels and is preferred for projects in urban areas where space is constrained.

Unlike other methods of tunnelling, which fight the pressure of the surrounding soil and rock, SEM works with the ground, using the surrounding geology as part of the tunnel’s structural support. SEM relies on something called observational engineering. The tunnel is monitored during excavation and engineers can make real-time adjustments during tunnelling.
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How sequential excavation works​


Workers excavate sections of each tunnel bit by bit. The area to be tunnelled is first divided into small sections, which are then dug out in sequence using excavators, starting with the top sections. The tunnels are carved out in small sections, called rounds – sort of like slicing a loaf of bread. tunnels are carved out in small sections, called rounds – sort of like slicing a loaf of bread.
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The next step is mucking, or removing the materials that have been excavated, as each section is dug out. Mucking involves hauling away rock, soil and other debris that would otherwise block the tunnel.

Once the mucking is complete, crews apply shotcrete, a special type of concrete sprayed onto the tunnel walls. This is like building a tunnel with spray paint. Shotcrete helps reinforce the tunnel structure and provides the first layer of support. It’s a quick-hardening material, which means it can stabilize the excavated area almost immediately, making sure the tunnel remains secure before moving on to further digging.

After reinforcing each section with shotcrete, workers then add a final lining made of cast concrete. This provides the tunnel with its permanent structure, adding strength and durability. The final lining also protects the tunnel from any wear and tear that might occur over time.
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Leo_Chan said:
A 6 year estimate is better than no 3 month announcement. ;)
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Slightly off topic but why is egw even estimated to be completed in 6 years when they've completed the vast majority of tunneling and most of the work has its own ROW and track length isn't anything crazy.


For comparison, ontario line has the same estimated completion time and that project hasn't even begun its big dig...

Between how little info. We get on cross town east, especially for a line meant to open in 2025, this whole crosstown project just seems messed up from the start 😒
 
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ProjectEnd said:
Is this the western extension NATM access hole?

View attachment 666430View attachment 666431
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That's the eastern end.

Digging is happening from Pearen Park several blocks to the west and working east.

Thaboss said:
Slightly off topic but why is egw even estimated to be completed in 6 years when they've completed the vast majority of tunneling and most of the work has its own ROW and track length isn't anything crazy.


For comparison, ontario line has the same estimated completion time and that project hasn't even begun its big dig...

Between how little info. We get on cross town east, a ao called completed line meant to open in 2025, this whole crosstown project just seems messed up from the start 😒
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Because the tunnels are only a small fraction of the total project. They still have to:
- excavate the stations
- finish the stations
- finish the emergency exits
- finish the tunnels
- built the viaduct
- finish the viaduct
- test everything

Dan
 
ProjectEnd said:
View attachment 664802View attachment 664804
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smallspy said:
That's the eastern end.

Digging is happening from Pearen Park several blocks to the west and working east.


Because the tunnels are only a small fraction of the total project. They still have to:
- excavate the stations
- finish the stations
- finish the emergency exits
- finish the tunnels
- built the viaduct
- finish the viaduct
- test everything

Dan
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Yep, I shot that in the two images above. But do they not need any sort of access point from the east going west? I can't imagine they just breakthrough to the current trackage inside Mount Dennis station and I think it's odd they would have shored a perfect square, about where the tracks would align, without it having to do with the tunnel further west.
 
They plan on digging from both sides eventually, and the section that joins the new tunnel to the existing station will be cut and cover. Piling works on the Mt Denis area are likely going to start soon by the look of this.
 
ProjectEnd said:
Yep, I shot that in the two images above. But do they not need any sort of access point from the east going west? I can't imagine they just breakthrough to the current trackage inside Mount Dennis station and I think it's odd they would have shored a perfect square, about where the tracks would align, without it having to do with the tunnel further west.
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Nope, they do all the tunnel's digging from the west end. What they'll do at the east is excavate the last couple of feet of the existing tunnels and cut them open in preparation of tying them in with the new tunnels to the west. Once they reach that point, they'll prep all of the formwork for tying everything together, pour the concrete, and then backfill.

Dan
 
smallspy said:
Because the tunnels are only a small fraction of the total project. They still have to:
- excavate the stations
- finish the stations
- finish the emergency exits
- finish the tunnels
- built the viaduct
- finish the viaduct
- test everything

Dan
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That still doesn't sound like six years' worth of work for a mid-sized transit project like this, though.
I think that like the Line 2 extension, it's a padded timeline that is meant to account for ML's consistent inability to deliver projects without major delays.
 
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