Saint-Dominique mechanical ventilation station

Project overview

As part of our program to upgrade the métro infrastructure, this fall we will be proceeding with the refurbishment of the St-Dominique mechanical ventilation station, located between Viger and the Ville-Marie autoroute near St-Dominique. The new structure will be built on the site of the existing building at 955 St-Dominique, at the Viger Street intersection, and will serve the Orange line between Champ-de-Mars and Place-d’Armes stations. 

Traffic in the sector during construction period

As of September 2015:

Automobile traffic:

  • One lane will remain open on Viger Street between de Bullion and St-Laurent Blvd. 
  • At the intersection of Saint-Laurent and Viger, a second lane will be available, one for right-hand turns and the other for going straight ahead.
  • 40 parking spaces will be eliminated between Sanguinet and Clark

Bicycle traffic:

  • The bicycle lane on Viger will be accessible during construction.

Pedestrian traffic:

  • The sidewalk on the south side of Viger will be closed between Hôtel-de-Ville and St-Laurent Boulevard. Pedestrians will be able to use the sidewalk on the north side of Viger between Hôtel-de-Ville and St-Laurent Boulevard.


The métro’s mechanical ventilation stations meet three essential needs:

  • Comfort ventilation: Regulates the ambient temperature and supplies fresh air for transit users by exchanging air from the outside with the air in the métro network. During the summer, the ventilation allows for the extraction of a portion of the heat generated by the acceleration and braking of the métro cars.
  • Night-time ventilation: Ensures a supply of fresh air for night workers carrying out routine maintenance work. These workers use diesel-powered vehicles to get around, as electrical power to the track is cut during the night.
  • Emergency ventilation: In the event of an incident, allows for smoke control and provides a safe evacuation route for transit users as well as unobstructed access for firefighters.

There are currently more than 80 mechanical ventilation stations across the métro network. A mechanical ventilation station is required between each two métro stations.

Yes, there is currently a station at the same location, but it has reached the end of its useful life and must be replaced. The project consists of dismantling the current ventilation station built in 1966 and building a new station that is quieter and more efficient. The new station will comply with current safety standards as well as with the city of Montréal’s noise regulations.

With the space between the Ville-Marie autoroute and Viger Street being limited, the station will consist of three separate buildings, each housing some of the equipment. We have worked with municipal officials to ensure that the architectural features of the station integrate well with the surrounding urban landscape.

The construction work will take a little more than two years. Based on the planned schedule, the work will start in September 2015 and be completed at the end of 2017.

Step 1

Worksite preparation

  • Installation of temporary fences around worksite and traffic obstacles on rue Viger
  • Installation of construction equipment

Approximate timeframe: one month

Step 2

Excavation of ventilation shaft

  • Demolition of existing ventilation station..
  • Since the ventilation station is located in an overburden area (above the bedrock), micro-blasting won't be required.

Approximate timeframe: nine months

Step 3

Concrete work for ventilation shaft and trench construction

  • Concrete work on floors, walls and ceiling

Approximate timeframe: nine months

Step 4

Installation of mechanical and electrical equipment

  • Deliveries of equipment at work site
  • Installation of equipment
  • Performance tests on mechanical equipment

Main equipment used:

  • Crane and delivery trucks

Approximate timeframe: six months

Step 5

Architectural finishes and landscaping

  • Construction of exterior building
  • All traditional trades usually needed to build the exterior structure are involved, including framing carpenters, bricklayers, roofers, glaziers, in addition to the landscapers

Main equipment used:

  • Trucks, forklifts, scaffolding and boom

Approximate timeframe: three months

  • Construction work likely to produce noise will be restricted to weekdays between 7 a.m. and 7 p.m. In order to respect the project timeline and avoid prolonging the construction period, there could be times when the work extends beyond the usual periods. In such cases, these extensions will comply with municipal regulations, and a notice will be posted on our web site.
  • For security reasons, some work might have to be carried out during the night (for example, installation of a barrier above the autoroute’s retaining wall). This work should not generate much noise, and a notice will be posted on our web site.
  • During construction, a specialized firm will ensure that the excavation does not do any damage to surrounding infrastructure, notably the autoroute’s retaining wall and the bridge on St-Laurent Blvd. Seismographs will be installed at strategic points on the work site and supervised by the firm in charge.
  • A traffic plan has been developed by a firm specializing in this area, working in conjunction with the Ville-Marie borough, the city of Montréal, Ministère des transports du Québec (MTQ), public security and the Montréal fire department. This will minimize the impact on the circulation of cars, cyclists, pedestrians and emergency services.

No. A mechanical ventilation station essentially exchanges air from the outside with the ambient air in the métro, thus bringing in fresh air for transit users.

No. There are no specific contaminants in a mechanical ventilation station. Rainwater or snow falling into the ventilation shafts will be collected by the métro pumping system and released into the municipal sewage system, as already happens throughout the métro network.

No. Once operational, the noise emitted by the ventilators will comply with municipal regulations. The ventilators, which are installed in the basement, will be equipped with powerful noise suppressors. The noise level outside the building will not exceed 50 decibels even when the two ventilators are operating at full capacity (an exceptional situation). Even in this case, the noise will be more or less equivalent to that produced by a household dishwasher, or so low as to be masked by normal human conversation or the area’s ambient noise level.

No. A mechanical ventilation station does not have the necessary infrastructure to be transformed into a métro station. Furthermore, there are no plans to this effect.

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