Pape Underpinning
The Ontario Line will be a 15.6-kilometre subway line that make travel easier within Toronto. As part of the construction, this structural steel underpinning supports the existing TTC Line 2 concrete subway tunnel at Pape Station in Toronto. This measure helps to prevent settling or damage while construction continues with the Ontario Line tunnels and station below.
Almost entirely made up of custom-fabricated steel members and plates, the Pape Station underpinning involves a highly complex sequence to ensure safety and stability of the infrastructure and active rail above.
- Approximately 950 tons
- 4” and 6” structural steel plates primarily used
- 97% of the project is custom built steel members and plates
Walters Group is supplying and installing the structural steel underpinning system. Approximately 950 tons of heavy structural steel, primarily composed of structural steel plates, safely supports the concrete tunnel while enabling excavation for the new Ontario Line underside of the existing Kipling-Kennedy line. These steel plates, ranging from 1” to 6” thick are anchored by 150-ton transfer girders. The team will construct the girders on site from three shop-fabricated assemblies that are approximately 50 tons each. 10, 45-ton needle beams will span between the transfer girders with the use of hydraulic jacks to precisely transfer and support the load of the existing concrete tunnel.
Constructing beneath an active rail line requires rigorous standards for both quality control and overall safety. As a result, the complexity of the steel fabrication and sequencing increases. In addition, the team is executing the work on a compressed schedule to align with the construction of the new tunnel. Material traceability requirements are also documented to ensure the highest standards of quality.
