Montreal rail junction realignment completed in tight window

A key suburban Montreal rail junction has now been realigned after some tight work scheduling over one weekend.

The work was perhaps the most complicated part of constructing the new so-called Le Train de l’Est route, Montreal’s $671 million suburban passenger rail line that will extend into the city’s off-island far northeast suburbs.

The line, operated by the Agence métropolitaine de transport (AMT), is scheduled to open late next year, and will connect downtown Central Station to Mascouche, 52 km away.

But while most of the line’s new construction is rather straightforward — indeed much if it takes place along a former CN Rail commuter line used half a century ago — a critical piece was put in place by this fall’s work.

In essence the junction project was a major grade separation.

Previously the junction in suburban Saint-Laurent saw a one track CN Rail freight line diagonally crossing at grade the existing two track AMT Deux-Montagnes line — another commuter line which runs from Central Station to the city’s northern suburbs. The new Mascouche line will also use this junction.

There were several problems with the old alignment.

One was that the CN line is non-electrical while the AMT operates electric-powered trains connected to overhead catenaries.

If CN Rail had oversized freight, the catenaries would have to be temporarily, and inconveniently, de-electrified. As well, AMT operates some 50 trains a day on the Deux-Montagnes line — its busiest route — and it plans to run another 16 trains on the new Mascouche line, creating a rather busy junction in a built-up urban area.

“It is a very challenging project, mostly on the technical front,” AMT spokeswoman Claudia Martin said.

Therefore, the project required that both the CN line and the AMT lines be physically cut out, with the CN line installed on a new bridge over the AMT tracks. Much of the CN overpass with its ballast, retaining walls, and abutments had previously been built leading up to this work.

In addition, the AMT commuter tracks had to be lowered — by a two-per-cent slope — to accommodate the CN bridge.

The most the CN line, because of heavy freight, could be sloped, was at .65 per cent grade.

Then there was also the associated infrastructure work. Track had to be yanked out and reinstalled, new signals added, and poles put in place to hold the catenary for the Mascouche line, which turns northeast at the junction and heads for the suburbs.

Electrification was the biggest hurdle.

“The 72-hour work block to put in service the junction was very tight due to the amount of work related to electrification,” Martin said.

A Type 80 catenary similar to early French TGV construction was used and the new line was powered by 25kV, the same as for the existing Deux-Montagnes line, she said.

But building new electrical train lines isn’t something done every day in Canada.

Said Martin: “We had a challenge when time came to find a local supplier, as there is lack of expertise in this field because this was the first rail electrification project in 20 years.”

Another issue for project planners was drainage. The sewer collector underneath the junction often filled in heavy rains. So a large underground retention reservoir had to be built that could meet a 24-hour, 100-year rainfall requirement.

Of course all this work couldn’t be done while the existing trains were in operation. So Deux-Montagnes passenger service came to a halt at 7.30 p.m. Friday, resuming Tuesday morning after the recent Thanksgiving long weekend.

The project cost $59.6 million, more than twice the original estimate, because of matters related to land acquisition, the reservoir, and noise barriers.

The barriers will in fact be as high as seven metres with a four-metre slope abutment with shrubs and climbing plants, with a three-metre plant acoustic screen.

CN Rail was the principal contractor, and used Montreal area contractor Loiselle for civil work and U.S.-based Mass. Electric Construction Co. for catenaries. Continuing rail and signal work is being carried out by CN.