Water drainage work around the vaulted ceiling area

 Water drainage work around the vaulted ceiling area

The catchment technique is used to channel the water that infiltrates through the métro system’s vaulted ceilings. To do so requires that a type of gutter be installed along the ceiling to drain the water and direct it to a plumbing system, usually hiden behind wall finishes and below train platforms, then on to a pumping station. Afterwards, the water is evacuated from the station and sent into the city’s water sewers.

This technique helps to keep the station dry and avoids the inconvenience related to water infiltrations. It also helps to maintain the integrity of the station’s architectural and electrical components and to keep it clean.

The arched ceilings above the tracks in the tunnel, and above the train platforms in the station.

The vaulted ceiling – the arch overlooking the rails – in Plamondon métro station.

These gutters are like pipes installed along the arched ceilings’ construction joints. On average, there are 16 to 18 such gutters per station, depending on its architecture. This component is an important part of the drainage system and serves to channel the water away from the station.

A picture of the gutters.

The water collected in the gutter is directed towards a drainage basin, such as the one featured here.

Several techniques were tried out in the past to minimize water infiltrations. Instead of trying to waterproof the concrete ceilings, as we once did, today we prefer to direct which way it goes. After all, water will always find a way, so it’s better that we find it first !

A situation that illustrates the necessity of installing a plumbing system behind wall coverings.

It’s normal for water to seep into any type of underground installation. There is no cause for worry and its presence does not alter the quality of the concrete.

It is mostly rainwater and natural water percolating through the ground below Montréal. The city of Montréal’s waterworks system also leaks and, in that case, a certain amount of that water will inevitably end up in the métro’s underground system.

It all depends on how deep the station is and the type of soil around it. The stations most prone to this problem are those that are below the level of the St. Lawrence River. For example, it appears there was an underground stream running near Frontenac station a few hundred years ago. As a result, the ground around that station is particularly saturated. That explains why, if you pay close attention, you sometimes hear water running behind the station’s walls. That water is being channeled away from the station by our drainage system.

An evaluation system was used to help us prioritize our actions, with points being given to each station, according to how serious the situation is.

The water run-off being drained away is not spring water! It is full of minerals and sometimes has a muddy texture. Residues accumulate and deposits become calcified inside pipes and in catchment basins. The drainage system’s components are all equipped with accesses for preventive maintenance, which is carried out on a regular basis by an assigned team.

In the past few years, a new water drainage system was installed in several stations. Indeed, in 2017, we completed the upgrades at Beaudry, Papineau and Sauvé stations.

In 2018, we plan on completing similar work at Édouard-Montpetit and Acadie, and begin preparations for the drainage system at De Castelnau and Fabre.

Once the water drainage system is installed, our crews regularly perform preventive maintenance work throughout the underground network.


In the long term, all métro stations will be outfitted with a water catchment and drainage system.

Because this type of work produces a lot of dust and noise that could bother transit users, our bricklayers and plumbers work mostly late in the evening and at night. When they are at work, the trains must slow down prior to entering the station. For safety reasons, their speed is limited to 32 km/h instead of the usual 72 km/h.

The scaffolding unit moves along the platform as work progresses (Square-Victoria métro station).

Extending between train platforms, this type of scaffolding is also used by our maintenance crews (bricklayers, plumbers and painters) who work in the métro network. When their work is finished in one station, the scaffolding is transported on a diesel-powered flatbed that runs on the tracks at night. The time allowed for this operation is very tight: only 45 minutes to dismantle the scaffolding in one station and another 45 minutes to set it up again in the next, in addition to the time needed for transportation.

Absolutely. Simply comply with the pictogram signs posted on the scaffolding directing passengers to either walk below it or between it and the wall. You must avoid walking between the scaffolding and the edge of the platform, as you would then be in the restricted zone where, for safety reasons, access is prohibited. 

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