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Toronto, Ontario


ACT was contracted to design and construct 3 circular access shafts at the site of the future York University Subway station. The three, 20 foot (6 m) inside diameter, shafts were constructed using secant piles.


The secant piles were 32” (813 mm) diameter and overlapped approximately 12” (300 mm). Shaft 1 was 71 feet (22 m), Shaft 2 was 68 feet (20.8 m), and Shaft 3 was 69.5 feet (21.2 m) below existing grade. Shafts were constructed using 40 individual secant piles with a vertical structural steel member installed in every fourth secant pile. At each shaft, a guard rail was constructed at the top, a shaft access ladder was installed, and a concrete base slab with sump pit was installed after the soil was excavated within the shafts.


ACT utilized a Bauer RTG 25 universal piling rig with our Front-of-Wall (FOW) system to install fully cased secant piles. ACT’s method included the use of a starter wall and styrofoam templates to ensure vertical alignment of the shafts. Pile installation records were electronically generated by the onboard computer and provided as-built documentation of the secant pile installations.



Client: Private

Owner: Toronto Transit Commission

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