January/February 2023 - 73

Support of excavation for station entrance
West Station and the vehicular traffic
from William R Allen Road made the
sequencing of installation of the
shoring a significant challenge.
During the construction of Cedarvale
Working below live traffic on Eglinton Ave.
station was constructed by GIP and
designed by Isherwood.
The new station is located at an
extremely congested location within
the city, the intersection of Eglinton
Avenue and the junction of the
separated highway, William R Allen
Road. The new station overlaps and ties
into the existing Eglinton West Subway
and Bus Station, which is serviced by
four main bus routes by way of a loop
whose entrance and exit are between
William R Allen Road South and
William R Allen Road North, all of
which needed to be maintained
throughout construction. The existing
Eglinton West Station also services the
Yonge University Spadina subway line,
which had to be underpinned to allow
for an excavation of 8.5 m (28 ft) below
the existing subway line for the future
ECLRT tracks. The combination of bus
and pedestrian traffic from the Eglinton
Station, traffic flow had to be maintained
on Eglinton Avenue, William R Allen
Road and the Eglinton West bus loop as
well as all intersections. Approximately
45,000 sq ft (4,200 sq m) of steel frame
decking with timber mats were
constructed and provided a staging area
for the construction activities below. The
traffic deck was installed in stages. The
initial stages were planned to maintain
traffic on one side of the road while the
shoring, shallow excavation and decking
were installed on the other side of the
road. These stages had to be further
divided when working on the north side
of the road due to all the intersecting
streets that had to remain active, i.e.,
William R Allen Road North and South
and the Eglinton West Station bus loop
ent rance and exi t . This staged
installation method necessitated the
design and construction of several small
temporary supports for the decking and
shoring that were later demolished
during the excavation.
Another challenge was the location
and depth of the existing subway box.
The support of excavation had to be
designed around it with a series of
perched shoring piles bolted to the top
of the TTC box to retain this small
height of soil. Challenges arose when
determining how to both install these
perched piles a top the existing subway
box and how to move the heavy
construction equipment from one side
of the box to the other because the box
dissects the middle of the future station
and required excavation. A concrete
pad was designed and constructed by
removing the top 1 m (3 ft) of soil and
replacing it with a lightweight concrete
slab that would remove some of the
dead load on the existing TTC box, and
disperse the load of the equipment that
would be travelling across the structure
and operating on top of the structure
without causing damage or undue
stress. Once the shoring piles had been
installed, the lightweight concrete slab
was removed, and the traffic deck was
installed spanning over the box to avoid
adding any load greater than the
existing condition on the structure.
Excavation Below the
Existing Subway
To support the existing subway line
within the excavation so the new
ECLRT tracks could pass below,
Entuitive, the project's structural
engineer, designed two 8 ft (2.4m) deep
plate girders bolted to the side of the
existing subway line and spanning
across the excavation. Crosslinx
DEEP FOUNDATIONS * JAN/FEB 2023 * 73
January/February 2023

Table of Contents for the Digital Edition of January/February 2023
