Project Spotlight: 54L Transmission Line Rebuild
February 25, 2026
AltaLink’s existing 54L transmission line is a single circuit 138 kilovolt line, approximately 24 kilometres (km) long. The line starts at the Canmore Substation, continues west through the Hamlet of Harvie Heights into Banff National Park, and ends at the Banff Substation.
The line was originally constructed in 1941 and has reached the end of its lifecycle. We are proposing to rebuild the line to ensure that a safe and reliable supply of power is available for years to come.
Project Stage: Consultation
Anticipated Project Schedule
Late 2026 Start Construction – Complete Construction 2030
The proposed project, subject to consultation, includes:
- Rebuilding approximately eight km of existing transmission line in and around the Town of Canmore
- Subject to further project development, rebuilding two segments of the line adjacent to Harvie Heights and Elk Run Boulevard in an overhead and/or underground configuration
- Rebuilding approximately 16 km of existing transmission line within Banff National Park
- Building a temporary transmission line to ensure reliable electricity supply during construction
- Vegetation management, including removing danger and hazard trees in and around the transmission line right-of-way (ROW)
Proposed transmission structures
The existing 54L structures are wood or steel and either monopole or H-frame structures. They are approximately 15 to 20 metres (m) tall and spaced approximately 120 to 200 m apart.
The proposed structures for the rebuilt line:
- Will be made of self-weathering steel that will have a natural brown finish
- Will be increased to approximately 20 to 30 m tall at approximately 125 to 200 m apart
- Will primarily use monopole structures, but H-frame structures may be required in some areas based on location and engineering requirements
- May require guy wires for corner or angle structures
- Will include an Overhead Optical Ground Wire on top of the circuit
Potential underground segments
AltaLink has identified two potential segments of the transmission line where we are considering locating the proposed line underground: one portion in the Harvie Heights area and one portion adjacent to Elk Run Boulevard in Canmore.
In these areas, the cost to complete the required vegetation management activities and the associated easement is potentially higher than the cost to install the transmission line underground. Placing transmission lines underground is generally only considered when it is a more technically viable or economic option than overhead transmission lines.
Temporary transmission line
AltaLink has identified the need for a temporary transmission line (also known as a by-pass) to support portions of the rebuild of the 54L transmission line. The by-pass line is required to maintain the flow of electricity to the Town of Banff while the existing line is being rebuilt. Wooden monopole and H-frame structures are proposed for this temporary line.
The temporary line is proposed to be constructed within the existing ROW, except for approximately four km in the vicinity of
Harvie Heights. In this area, the temporary line is proposed along Harvie Heights Road and Palliser Trail.
Draft Detailed Impact Assessment
The AltaLink 54L project runs through multiple jurisdictions. For the portion of the project in Banff National Park, AltaLink is engaged with Parks Canada to develop a Detailed Impact Assessment (DIA), as required under the Impact Assessment Act, 2019. The DIA identifies baseline conditions within the project area, assesses the potential effects of the project on natural and cultural values and proposes mitigations to ensure there are no significant adverse effects.
Over the course of the coming months, AltaLink is seeking feedback from the public, stakeholders and Indigenous Nations on the draft DIA. Based on feedback and in consultation with Parks Canada, AltaLink will finalize the DIA and submit for approval. Click here to view the Draft DIA Summary, the Draft DIA and DIA Appendices.
