Metrolinx crews on Scarborough Subway Extension prepare for excavation

Metrolinx's project team responsible for the Scarborough Subway Extension is ramping up efforts to prepare for excavation.

The extension, which broke ground in June, will provide seamless, reliable transit to key areas in Scarborough and service approximately 105,000 riders each day.

Crews are preparing a launch shaft at the northeast corner of Sheppard and McCowan. This large excavation will be used to lower the tunnel boring machine into the ground next year.

The work of ‘secant piles’

“We’ve completed drilling over 200 secant piles so far as part of our preparations to begin excavation,” said Uhland Konrad, Design and Build director for Strabag, the contractor in charge of tunnelling underground for the project.

Those secant piles are reinforced concrete columns used to create a water-tight barrier around the perimeter of the area that will be excavated for the launch shaft. 

Strabag was selected through procurement to construct the tunnel for the Scarborough Subway Extension Project. The company is a global leader in tunnelling technologies and has built complex transportation infrastructure in more than 60 countries. That expertise will be used on this project, which will see the construction of a launch shaft that is approximately 80 meters (262.5 feet) long, 30 meters (98 feet) wide and 25 meters (82 feet) deep.

“Tunnelling requires extensive experience,” Konrad said. “We understand how important it is for the public to have access to transit in this part of the city and we are working hard to complete the project as quickly and safely as possible.”

Sheppard and McCowan is a busy intersection and the safety of crews working inside the construction site as well as those walking outside is a priority for all those involved in the project.

Safety is paramount

“Safety is a major priority for us and our partners at Metrolinx,” Konrad explained. “We are staying aware of not only what is happening within the construction site, but also around the area. People walk past the site often, so we have safety checks at the gates to make sure everyone is safe.”

Metrolinx and Strabag have also installed safety signage around the site, reminding people to be aware of their surroundings as they move past

“Having the construction completed as quickly and safely as possible is important for everyone involved,” Konrad said.

Being a good neighbor to the local community is very important and Strabag has already put measures in place to reduce the impacts of noise and vibration from construction at the launch shaft site.

Noise and vibration measures

“Noise and vibration monitoring equipment have been installed on site and in different locations in the area to keep a close eye and ear on construction activities,” Konrad explained. “We’ve also installed a movable noise wall that is used to reduce sound from construction activities on site, especially when work is being done in the evenings or on weekends.”

Dust can be another common problem at construction sites when it’s windy, so Strabag is using water trucks to spray the worksite nearly every hour to minimize impacts on the surrounding community.

Once teams complete the excavation and prepare the tunnel launch shaft, the tunnel boring machine will arrive on site. Then, crews will lower it into the launch shaft where it will begin working its way south underneath McCowan Road.

Community notices about the ongoing construction taking place at Sheppard and McCowan will continue to be updated and sent out to residents and businesses in the surrounding area.