Préfontaine is a subway station on the Green Line of the Montreal Metro rapid transit system operated by the Société de transport de Montréal (STM). Located in the district of Hochelaga-Maisonneuve, it originally opened on June 6, 1976 for the Montreal Olympic Games as part of the extension of the Green Line to Honoré-Beaugrand.

Designed by architect Henri Brillon, it is a regular side-platform station built partly within a tunnel that features a large open area entrance and mezzanine. The original design was centered on using skylights to deliver vast quantities of natural light to fill the mezzanine area and reach down into the tunnel.

After nearly 30 years, the Préfontaine subway station was in serious need of a complete overhaul to replace leaky skylights and rebuild the distinctive architecture. The Société de transport de Montreal hired Provencher Roy Associés Architects to tackle the major revamp project.

The Préfontaine project presented three very distinct challenges:

1. Sustainability – Montreal has extremely cold and harsh winters. Keeping metro stations warm during the cold months is of primary importance for passenger comfort. The Préfontaine station needed to flood its interior and tunnel areas with natural light to warm and illuminate the platform areas.
2. Looks - The renovation had to keep the look and feel of the original 1976 design while completely upgrading and replacing the broad expanse of glass and skylights. There could be no compromise. The famous design elements had to be carefully preserved.
3. Performance – Any skylight system in Montreal has to be highly weather and temperature resistant. This is a given. However, a subway station is additionally subjected constantly to a huge piston effect which is produced by trains entering and leaving the station. This continuous thundering vibration demands an extraordinarily tough solution. And one that will stand up to this effect for years and years.

Solution
Unicel Architectural was selected as a candidate for the project. As a first step Unicel had to provide a working sample for performance testing to ensure compliance by both engineers and the client organization. The Unicel skylight system was tested for yield performance, resistance to water infiltration, and its ability to absorb the trains’ relentless piston effect.

The Unicel skylight provided an internal guttering system designed with pressure-equalized rain screen technology that incorporates the largest water infiltration and condensation guttering system in the industry. Additionally, it was fabricated with notched rafters and coped purlins that come together at their intersection to accommodate gutter continuity and thermal expansion. This ensured a plumbing system that does not rely on any sealant to perform.

Furthermore, the skylight systems drew on Unicel’s Canadian experience with harsh winters and extreme temperature variations, and benefitted from decades of expertise in the installation, water management, condensation control and thermal movement accommodation for horizontal glazing applications.

The Unicel skylight systems solution was selected after a successful testing process. 3D design capabilities ensured the accurate specification of all of the structure’s multi-angle components including complex ¼-inch (6mm) break metal, all of which were designed and fabricated by Unicel. This resulted in skylight systems that could be easily installed without additional field cutting or onsite modification requirements.

Today
The Préfontaine Metro Station today has re-captured its former esthetic glory. It features the same generous levels of natural lighting and distinctive design to make it a noteworthy example of public transport architecture. But more than just a pretty face, the skylight systems are also built to withstand the most extreme temperatures and rugged vibrations.

Participants

• Client: Société de transport de Montreal
• Architect: Provencher Roy Associés Architectes, Montreal, QC
• General Contractor: MGB Associés Inc., Laval, QC
• Glazing Contractor: Unicel Architectural, Longueuil, QC
• Skylight Manufacturer: Unicel Architectural, Longueuil, QC