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Ottawa Light Rail Transit - Design

Owner:
Client:
Service:
Tender design, preliminary and full detailed design including execution drawings for the mined twin track running tunnel, three mined station caverns and access shafts.
Estimated cost: Commencement:
March 01, 2012
Completion date:
Ongoing
Location:
529 Albert St
Ottawa, ON K1R 7Z0
Canada
Technical data:
Geology description:

The geology varied between competent limestone and fractured shale. A soft ground section included variable glacial till deposits of sand, silt and clay layers and a groundwater table close to ground surface.

Geology types:
Activity:
Categories:
Bid cost: Final cost:
$2.1 billion CAD
Service areas:
Construction methods:
Tunneling under:
Tunnel length:
2.5km
Description

Ottawa's Confederation Line runs from Tunney's Pasture in the west to Blair station in the east, is 12.5 km long and includes 15 stations. The central piece is a 2.5 km long tunnel, running under the central business district of the city, including 3 underground stations. The twin track running tunnel and 3 underground stations were designed using the mined construction method in order to minimise surface disruption. The underground stations are located adjacent to existing, sensitive and historic buildings and required detailed risk mitigation measures during design. An innovative engineering solution involving a tailor-made excavation sequence and permanent tension ties spanning the cavern was developed.

Downtown station located between high-rise buildings
Downtown station construction sequencing including tie-backs
Cavern construction under way
Mined Caverns directly adjacent to existing basements
Special Excavation Sequences incorporating pre-tensioning
Large-Scale 3D Numerical Modelling incorporating the surroundings