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Don Valley Parkway/Canadian Pacific Rail Grade Separation
Toronto, Ontario
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Don Valley Parkway
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Tunnel jacking was used for the Don
Valley Parkway grade-separation project. |
When the Don Valley Parkway/Canadian Pacific (CP) Rail underpass
was completed in 1990, it was the first project in North America
to incorporate technology for jacking large structures under operating
train traffic. Today, the underpass serves as part of a ramp to
a busy highway. The reinforced concrete tunnel structure weighs
2200 tons (2000 tonnes), has an arch-like cross section 105 feet
(32 m) long x 29.5 feet (9 m) high x 36 feet (11 m) wide, and was
fabricated adjacent to two CP Rail mainline tracks—one of
Canada’s most heavily traveled railway lines. The tunnel was
then moved into its final position beneath the operating railway
by a system of hydraulic jacks, in concert with mining operations
carried out at the lead face of the structure.
The tunnel was cast in two longitudinal segments on a 3-foot (0.9-m)
thick heavily reinforced concrete thrust base. The base slab’s
weight counteracted the jacking forces as the tunnel moved forward.
A mining shield provided on the structure’s lead face was
designed for expected geotechnical conditions at the site.
The total jacking and mining operation was 92 feet (28 m) long.
CP Rail maintained train traffic under slow orders, but without
schedule interruptions during construction. Following each stroke
of the 10,000-psi (69-MPa) hydraulic jacking system, workers carefully
excavated within the structure and beneath the protective shield.
Laser controls were used to maintain the structure’s alignment,
which was skewed to the railroad embankment. Monitoring equipment
recorded soil movements in the embankment ahead of the advancing
structure and adjacent to an existing highway arch, as well as any
settlement of the railroad tracks.
At the time of construction, the project involved a number of unique
features: it was the largest such structure to be moved by jacking
and mining, the first arch structure to be built in this manner,
and the first skewed structure to be so moved. The project demonstrated
that tunnel-jacking methodology is compatible with North American
construction techniques and can be a cost-effective system for the
construction of grade separations beneath heavily traveled railways,
highways, or even airport runways.
Project Credits
Owner: Municipality of Metropolitan Toronto, ON
Consultant: Delcan Corporation, Toronto, ON
Subconsultant: Cementation Projects, Ltd., London, UK
Geotechnical Consultant: Golder Associates, Toronto, ON
Contractor: Matthews Contracting Inc., London, ON
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