New Alexandra Bridge design chosen by NCC
The replacement for the 1901 bridge has been chosen to reconnect Ottawa and Gatineau once the old bridge is demolished in the coming years.
Blair Crawford, Ottawa Citizen
Published Jan 23, 2025 • Last updated 29 minutes ago • 2 minute read
Motion, a graceful triple-arched bridge inspired by the flow of the Ottawa River and the endangered American eel, has been chosen as the design to replace the aging 124-year-old Alexandra Bridge.
The National Capital Commission unveiled the design at its Jan. 23 board meeting, following months of study and public consultation. Motion is one of three designs shortlisted for the new bridge, the construction of which is set to begin in 2028.
The others were Echo, a modernized take that preserved the distinctive outline of the existing bridge, and Rendez vous, which had two spans of 290 metres and 220 metres suported by a single pier in the river closer to the Quebec side. Rendez vous has two arches, compared to the triple arch of Motion, and would be 15 metres taller than the existing towers on the Alexandra Bridge.
The NCC used seven objectives to evaluate the designs:
- Bridge expression
- Integration into the capital and natural landscape
- Public space and user experience
- Views and visual experience
- Sustainability and the environment
- Construction cost and schedule
- Operation and maintenance
All three designs scored well and exceeded the minimum threshold, but Motion placed first when scores were averaged, said Bruno Fabien, director of engineering assets for the NCC. Motion scored particularly well in the amount of public space it will provide and for its visual experience, he said.
The design gives “a balance between transparency and mass to highlight symbols of the natural landscape” while providing “captivating and enhanced” views from both upstream and downstream, he said.
Motion also has the lowest slopes on its approaches.
“In terms of user experience, Motion stands out from the other concepts,” Fabien said.
Motion incorporates a pedestrian walkway with viewing areas on the west, upstream side of the bridge, while two lanes of traffic and a separate space for bicycles would be contained within the width of the archways.
Echo most closely matched the look of the Alexandra Bridge’s distinctive profile, but “the opacity of the structure and irregularity of the design across the span introduced some complexities that could influence the experience of users.” he said.
Rendez vous had the least environmental impact because of its single pier, but is significantly taller and had more impact on the city skyline. It also scored lower than Motion on how well it reflected the natural landscape, he said.
All three designs would cost about the same to build.
The replacement is a joint project of the NCC and Public Services and Procurement Canada. Built in 1901 as a truss-style railway bridge, the Alexandra Bridge carried about nine per cent of the vehicle traffic between Ottawa and Gatineau and 33 per cent of bicycle and active use travel. Despite numerous upgrades, years of road salt use have corroded the structure to a point it can no longer be repaired.
A complete design of the new bridge is expected to come back to the NCC board for approval in late 2025.
https://ottawacitizen.com/news/new-alexandra-bridge-design