TORONTO, ON
College Station
College Station is an existing subway station in downtown Toronto, located at the intersection of Yonge Street and College Street.
It’s a high-traffic subway station undergoing major renovations in a bustling area.
The Yonge and College area in Toronto is very dense. As such, to accommodate the two elevators a new concourse must be built below street level on top of the existing TTC subway box.
The project involves making College Subway Station more accessible by adding two elevators to its station platforms. The work is part of the TTC’s Easier Access Program to make its stations more accessible to all.
PROJECT HIGHLIGHTS
CLIENT
TTC
ARCHITECT
Stantec
OUR ROLE(S)
Structural Engineering Consulting
SIZE
BUDGET
MARKET (OFFICE)
KEY CONSIDERATIONS
Challenge One
The condition of the existing buildings at this site, since the east and west concourses are being built underneath bustling commercial and retail buildings.
Solution One
We specified temporary shoring posts with jacking forces to transfer the floor loads away from walls being demolished. We then specified steel beams within the openins with their own jacking forces to ensure proper load distribution.
For the new openings into the existing TTC structure, we employed a reinforced concrete approach and specified dowelling into the structure, creating a lintel on top of the existing roof with rebar ties to pick up the tension above the opening.
Challenge Two
Excavating underneath the Yonge/College intersection to make room for the concourse without shutting down traffic and without causing unbalanced loading on the TTC structure.
Solution Two
To ensure we didn’t shut down this critical intersection during construction, we designed the excavation to be done in a systematic, staged way, ensuring minimal impact to the road and businesses on either side.
Our team also planned the excavation in a staged way that ensured the TTC structure remained balanced. We designed a sequence of excavation in a top-down approach that combined with the construction of the concourse. Working in sections, a portion of the roof slab of the concourse was first built on top of the soil to be excavated, followed by excavation underneath. This proceeded repeatedly in stages across College Street.
