*Project led by Michael Meschino, David Stevenson and Mike Hillcoat while employed at a previous firm.
Moriyama & Teshima Architects
138-m long x 20-m wide x 15-m deep station with 142-m running structure
Structural Engineering Consultant
2001 Canadian Consulting Engineer Award of Excellence – Transportation
2002 Ontario Concrete Awards, Cast-in-place Concrete, Innovation Category
The Toronto Transit Commission’s (TTC) Leslie Station, located at Sheppard and Leslie Street, serves thousands of bus and subway commuters every day.
The station structure is cut about 15-m deep into an earth embankment and acts as a retaining structure. Anticipating future development in the area, the station was designed to accommodate connections to adjacent sites.
The running track is a 142-mlong, three-celled box structure. The centre cell provides public access between the station and the east entrance at Leslie Street.
Challenge: The structure sits in difficult, varied ground conditions. A soft clay layer increases lateral pressure from the retained embankment. The penetration of a confined aquifer generated high-buoyancy forces. Moisture loss in the clay could result in substantial settlement beneath the building. The station is 600 millimetres from an existing masonry building that sits on shallow foundations.
Solution: The team used the station’s mass and rigidity to resist earth and water pressures while providing a clear span structure – at no added cost. Other solutions included: a stiff excavation support system; a dewatering system to de-pressurize the aquifer; and a groundwater recharge system to replenish moisture loss in the clay during construction.