Vallée-du-Saint-Laurent

Project summary

Why?

Enable additional electricity to be transmitted from northern and eastern Québec.
Increase the transit capacity of existing 735‑kV lines that are operating at full capacity.
Secure the electricity supply to major load centres.
Improve grid resilience and reliability in the face of increasingly intense weather events.

How?

Build two 735‑kV substations and approximately 200 km of 735‑kV lines.

When?

2032

Line routes and substation location under study

Download the map of the line routes and substation location under study – April 2026 [PNG 2.9 MB – in French only]

Towers

Transmission towers support the high-voltage conductors of overhead power lines. Their shape, height and sturdiness (mechanical strength) depend on the stresses to which they are exposed. For the Vallée‑du‑Saint‑Laurent project, mainly four-legged towers and guyed V- towers will be erected.

Get more information on these types of towers

The right-of-way of the planned line

A right-of-way is the cleared corridor under power lines. It is important to maintain a safe distance between the conductors making up the line and the surrounding vegetation. Transmission lines are not covered by an insulating sheath. Instead, the air around them provides insulation. So, it's important that nothing come close enough to the lines to create an electric arc.

The right-of-way is also used to install, operate, maintain and repair overhead and transmission lines safely.

The width of a right-of-way depends on the voltage of the line, among other criteria. The higher the voltage of the line, the greater the clearance required and the wider the right-of-way.

For the Vallée‑du‑Saint‑Laurent project, the line routes under study run along existing lines for most of their length. This will reduce the total width of the rights- of-way by about 20% to 30%, in turn reducing the clearing required.