PSPC extends Alexandra Bridge closure

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Grating on the bottom of the bridge showing corrosion and section loss. The grating is being removed as part of the on-going boardwalk and articulation repair project.

 

Ontario Construction News staff writer

An inspection of the steel structure of the Alexandra Bridge between Ottawa and Gatineau revealed “more severe deterioration due to corrosion” forcing Public Services and Procurement Canada (PSPC) to extend the expected time to complete essential rehabilitation and repair work.

“We have completed several rehabilitation projects to ensure that the bridge remains safe for users until it can be replaced,” said Paul Lebrun, chief engineer, National Capital Region Bridges. “Despite all of this work, detailed inspections tell us that the bridge continues to deteriorate, mainly due to corrosion.”

The closure, originally expected from October 2023 to fall 2024, is now extended to February 2025.

Public Services and Procurement Canada (PSPC) is working with its partners and stakeholders, including the cities of Gatineau and Ottawa, to minimize traffic disruptions to its NCR transportation network.

In 2023, the Government of Canada awarded a $14.95-million contract to Arup Canada Inc. for the professional services of a technical advisor to support the Alexandra Bridge replacement project.

Work will replace the120-year-old end-of-life structure with a new bridge that will provide long-lasting benefits to the communities on each side of the Ottawa River.

Construction is planned to take place in three stages, with deconstruction work estimated to start in 2028, and the new bridge expected to open in 2032.

Pomerleau Inc. will provide construction management services to perform essential maintenance to keep the bridge safe and in service until deconstruction.

The initial value of the contract is $32 million, which covers the projected cost of structural repair work on the boardwalk and the articulation joints, as well as the construction manager’s fees.

In 2019, the government mandated Public Services and Procurement Canada (PSPC) to replace the Alexandra Bridge.

The decision to replace the bridge has been taken very seriously. We commissioned many reports and studies on replacing the Alexandra Bridge, which helped us make evidence-based decisions and plans. The studies identified concerns about areas of the bridge including:

  • the boardwalk
  • structural articulation
  • buckling
  • eye bars
  • pins of the truss members

The Alexandra Bridge is the only example of a true-pin cantilevered truss bridge in the region. Truss bridge designs are less common in modern structures due to:

  • higher construction costs
  • an excessive area of exposed steel that is subject to corrosion (corrosion is a key factor behind the need to replace the existing bridge)
  • connection areas that are difficult to inspect, maintain and repair (this increases the cost of maintenance)

“We understand the historical and cultural significance of the Alexandra Bridge. The bridge has a Level II heritage rating (National Historic Importance), and an engineering significance (designated as a National Historic Civil Engineering Site),” PSPC said on the project page. “While it’s a familiar landmark within the Ottawa-Gatineau region, it’s not designated as a National Historic Site in the Directory of Federal Heritage Designations; therefore, is not subject to mandatory protection and conservation.”

The new bridge will be designed in a way to avoid corrosion-prone details and structures. This will help ensure it can be maintained in a good shape for a longer period and serve many generations.

The bridge is expected to include 2 lanes for vehicle traffic (that could accommodate high-capacity transit in the future) and a by-directional cycleway separated from a large pedestrian space. It’s also expected to be wider than the current bridge, with clear separation of pedestrians and cyclists. And finally, it will include seating to provide safe rest points and locations to enjoy the view.

The new bridge design will consider the history and unique setting of the existing Alexandra Bridge.

PSPC is collaborating with heritage specialists and other stakeholders to preserve and commemorate the legacy of the bridge. A heritage impact analysis is underway to inform the project team on how heritage elements can be preserved or commemorated in the new bridge design and Indigenous communities will be consulted about heritage, sustainability and potential impacts on the river and landscape.

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