Plaza Bridge and Confederation Square Rehabilitation

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West elevation of barrier wall at Sapper stair opening.

The Challenge

The Plaza Bridge and Confederation Square rehabilitation project had three goals: the structural rehabilitation of the Plaza Bridge, the upgrade of the area’s infrastructure and the rejuvenation of the landscaping. The project was tendered and awarded in the Fall of 1997, with construction to be completed by December 1999, in time for the millennium celebration in Ottawa.

The Solution

Concrete was used extensively in the Plaza Bridge and Confederation Square Rehabilitation project. Cast-in-place concrete was used for the structural rehabilitation and for the wear surface of the bridge. Intricate precast concrete was used extensively throughout the project for railings, balustrades, stairs and light bases in the urban landscaping.

Special Features

Special detailing and quality workmanship was incorporated throughout this project. Three aspects of the concrete work were deemed as exceptional: the combination of cast-in-place and precast concrete used in the bridge balustrades, the intricacy and quality of the precast concrete architectural features (over 1000 components) and the unique concrete mix for the cast-in-place bridge soffits.

Construction Methodologies

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West arch at Sapper stair opening showing soffit work.

Bridge Soffits

Underground Services (1983) Ltd. developed forming and concrete placement techniques to ensure bonding of the new concrete with the pre-prepared in-situ concrete surface, while ensuring good fin definition and transfer of the wood grain from the form boards to match the original bridge construction. The special concrete mix, allowed it to be pumped into forms suspended below the bridge soffits and meet outlined criteria such as: low shrinkage, fluidity, low alkali content and low permeability for an impermeable cover.

Balustrades

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North elevation of bridge.

For the concrete in the vehicle/pedestrian barrier walls, a combination of cast-in-place and precast concrete was used. Cast-in-place concrete was used in the bases and stanchions of the barriers and precast concrete for the balusters and caps.

To accommodate grade changes and the desired barrier wall profile, Right Forming (1996) Ltd. devised a system of closed forms for the base section. Lafarge Canada Inc. developed a self-compacting concrete mix to properly fill the formwork that, when sand blasted, would provide a finish comparable to architectural precast concrete. The precast concrete wall sections of the balustrade were set between the stanchion’s, steel reinforced stanchions were cast using the same self-compacting concrete as the base section. A decorative precast concrete cap was then added to complete the assembly.

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Project Team
Engineer Stantec Consulting Ltd.
Architect Phillips Farevaag Smallenberg Inc.
Contractor Doran Contractors Ltd.
Concrete supply Lafarge Canada Inc.
Bridge formwork Underground Services (1983) Ltd.
Architectural formwork Right Forming (1996) Ltd.
Precast concrete Central Precast Inc.

pdf Plaza Bridge FS 393.66 Kb