Getting ready for a new bridge

After more than a century of continuous use, the Alexandra Bridge, crossing the Ottawa River to link Ottawa, Ontario, and Gatineau, Quebec, has almost come to the end of its serviceable life and will be replaced. The bridge opened in 1901 to steam trains, trams, carriages and pedestrians. The bridge was closed to vehicular traffic in October 2023 to perform stabilization work so it can continue to be safely used until it's replaced with a new bridge. Today, the bridge is used by pedestrians, cyclists and those who use mobility devices (such as electric wheelchairs and e-scooters), as well as a host of other users. The bridge is expected to reopen to vehicles again in 2024.

The bridge’s engineering status

Paul Lebrun, Chief Engineer of National Capital Bridges, and his team at Public Services and Procurement Canada (PSPC) monitor and maintain the Alexandra Bridge. In addition to their ongoing work to keep the bridge safe for public use before its deconstruction, Lebrun and his team have been conducting and continue to conduct comprehensive inspections every 2 years. The inspection in 2017 showed that the bridge was reaching the end of its life cycle. The report listed 17 different issues impacting the strength and integrity of the bridge, including:

1) ?rust, holes and cracks/breaks in the steel

2) bridge parts that need to move are seizing due to rust. This is causing parts of the bridge to absorb additional load, as well as the loosening of parts creating gaps around pins

These are the known locations on the bridge where the lack of movement is affecting the bridge's ability to safely hold a load:

3) bent, buckled and deformed steel

These are the known locations on the bridge where there is buckling:

"The deterioration of the bridge is mainly due to exposure to nature's elements and exposure to salt from winter de-icing operations and spray from vehicles. Many areas are difficult or impossible to clean, such as the grating and stringers under the boardwalk or connections below deck," says Lebrun.

Over the years, Lebrun's team has been checking and replacing parts or building up sections to compensate for the impacts to the corrosion of the steel. It's complex work. Many parts of the bridge are difficult to access and finding experienced iron workers to do the repairs is getting harder.

"I think we all like or love the Alexandra Bridge, but our primary responsibility is public safety," says Lebrun.

Since 2009 the bridge has been closed more than 33% of the time. "If you look at the condition of the bridge and all the mitigation measures that are on it: regular inspections, the addition of sensors, patching or repairing portions, imposing maximum vehicle weight restrictions, it's all showing that the bridge is coming to the end of its life cycle," says Lebrun. PSPC is doing this work to ensure the safety of all who use the bridge.

Environmental impacts

The existing Alexandra Bridge also presents some environmental challenges. The open-grated lane and centre bridge storm drains do not filter runoff so road salt and debris from vehicles go directly into the Ottawa River. The new bridge design will consider solutions and find ways to protect the river.

Michelle Fairbrother, Acting Senior Environmental Advisor with PSPC, is working with the National Capital Commission - Commission de la capitale nationale (NCC) and the PSPC project team to study the environment. The team uses the information to develop mitigation measures, inform criteria for the replacement bridge design, and find opportunities to enhance or restore habitats post-construction.

They also use several methods to gather environmental data. "We need to understand the current conditions. So, we did a lot of field work, including terrestrial surveys and underwater recording of the aquatic environment. We wanted to study the fish, wildlife and plants that live around the bridge," she says. The team also referred to past records of species at the site. Fairbrother says, "These records are important because if we didn't see one of the species in the records during field work, it doesn't mean it's not there."

"We know construction will impact both ends of the bridge and the river. We want to do as much as we can to protect the environment, so every bit of information is useful," she says. Some species found last year during field work include the Barred Owl, Yellow Perch and Black Swallowtail butterfly.

Understanding the current environmental condition and where changes happen is important. It's the team's job to make sense of potential environmental impacts during and after construction so they can provide mitigation measures that will be effective.

"Another big part of what we're working on is how to monitor and show that environmental guidance is being implemented. We are assessing and providing advice to reduce and avoid environmental impacts before the work, during project activities, and following project completion to ensure the environment is protected,” says Fairbrother.

The department is also aiming for Envision Certification for the new bridge. This is similar to the Leadership in Energy and Environmental Design (LEED) for buildings. The certification, which is administered by an independent agency, gives PSPC a way to track and check that environmental, social, and economic goals identified for the project are being met.?

The work is extensive

It takes a community to replace a bridge properly. In addition to the team working on structural inspections and environmental studies, other teams are evaluating the heritage, archaeological, social and economic impacts and gender-specific influences. Ongoing public engagement and discussions with Indigenous communities are helping us to include multiple points of view into the new bridge project. The relationships we are building are helping with this project and with PSPC's and the NCC's efforts towards reconciliation.

To learn more, check back as stories are coming on these topics. Also, you can visit the Public Services and Procurement Canada and the National Capital Commission websites for more information.

For other stories about the work at PSPC, visit the Our Stories page.

You can also read the accessible version of this article on our website.