Going deep into the ground at Laird Station
In building the crosstown, we’re working to minimize disruption – here’s how we’re doing that at Laird. We’re using a sequential excavation method (a mining technique) to excavate the underground portion of the station – where the platforms and concourse levels will be built around the current LRT tunnels.
This means once the excavation is complete for the station entrances, a total of two at Laird, we will start mining sideways under the roadway to make room for the platforms and concourse. In contrast, the cut and cover method means excavating vertically from the road.
“Using the sequential excavation method allows us to minimize impacts to our neighbours while working in a small area,” said Aleix Giralt Belata, project manager for Laird Station. “I am proud of the positive progress our team is making on deep excavation for the station entrances as we gear toward upcoming mining work.”
The mining method will be used on four station sites – Laird, Leaside, Avenue and Oakwood. These are some of the deepest and longest stations on the line, with very small intersections and dense populations. The mining method reduces the amount of excavation and utility relocation required, and causes less disruption to pedestrians and road users.
The graphic below illustrates different equipment used for deep excavation at Laird and the site setup.
1) Reduced tail swing excavator: This excavator in the pit digs and stockpiles the soil it removes.
2) Extended boom excavator: This excavator has a longer arm and reaches down to the stockpile and loads the soil on to trucks to remove from site.
3) Extendable stairs: These stairs provide access to the site. Additional stairs are added as the excavation moves deeper.
4) Steel corner brace: These are corner braces to support the excavation.
5) Tie-back drill-rig: This machine installs the tiebacks around the sides of the excavated area.
6) Mini excavator: This equipment is versatile and can transform to handle different activities such as moving soil or scraping down the sides of the excavation.