Eastern REM: 500m underground part will be applicable

Yes, that is possible today. Today we come to a solution, which is to get part of the tunnel, acknowledged Thursday at ICI RDI Chairman and CEO of CPDQ Infra, Jean-Marc Arbod. And so he returned to the words of the organization last winter, according to which it will be the only possible air project.

According to Mr. Arbod, this integration of air and underground has several advantages.

It allows you to have a direct connection to the entire subway network in Montreal. What was in the air was more complicated. It also allows for a back station, i.e. a turning area for trains which makes it possible to increase the theoretical future frequency of the project.revealed in an interview with the program Live with Patrice Roy.

According to the 33-page document, the . file CPDQ Infra has studied up to 50 scenarios for REM East Road to get to this solution.

The first study was conducted in the first quarter of 2021 by Canadian-American engineering firm Aecom-Systra, with support from the French Systra Group. This resulted in the publication of six Underground Scenarios for Downtown, in February.

The second study, presented as complementary expertise, was conducted by the Spanish company Geocontrol SA, which presented its conclusions in August.

Spanish company Geocontrol SA has implemented 3D models that integrate the presence of rocks and groundwater on virtual roads at REM.

Photo: CDPQ Infra

Six other scenarios were studied

In this new compilation, six scenarios were selected for analysis.

The first four scenarios relate to tunnels approximately 4.5 kilometers long under René-Lévesque Boulevard.

The first passes between the yellow and orange lines of the metro with a transition to the air at the future Cartier station (Pont Jacques-Cartier). The second will also pass between the yellow and orange lines, but with a shift 1 km east of the Canadian Pacific (CP) Trails.

In the other two scenarios, the tunnel will deepen below the yellow line. One will travel to the air rail west and the other will travel to the east.

A tunnel under Rue Saint-Antoine was also studied by Geocontrol, but was rejected due to a sewer built in 1877 along the way.

The sixth and final scenario, Suggest a new option, is a tunnel about 600 meters high at the western end of the road that will take out light rail trains before crossing the metro lines.

This improvement will now be added to the reference project, confirms Harut Shetilian, Vice President of Corporate Affairs, Development and Strategy at CDPQ Infra.

The new option was chosen: a tunnel of less than 600 meters

A tunnel about 500 meters long between De Bleury and Robert-Bourassa is the proposed new option.

Photo: CDPQ Infra

Geocontrol tried to think outside the box to come up with a tunnel solution that would bury the last 600 meters of the road and build a back stationAccording to Mr. Chitilian.

This rear terminal, from an operational point of view, is a major asset.

In particular, it would make it possible to increase the frequency of trains and better connect REM East to existing networks, the CEO of CPDQ noted. Thus, the station of the line, Robert Borassa station, will be underground and the route will take advantage of the landing on Boulevard René-Lévesque to go to the air section, near rue Jeanne-Mance.

REM de l’Est: Interview with the President and CEO of CDPQ Infra

The importance of the path has been questioned

Mark Durand, an engineer in applied and geotechnical geology, considers these two studies to be of very high quality. Unfortunately, I find that these two routes are poorly geologically chosen. We target complex sectors due to the presence of unconsolidated deposits. Anything north of Sherbrooke Street will provide good conditions, such as a 500-meter tunnel. They chase problems, but that’s their way, the problem.

When asked about the choice of pathways offered to engineering firms, Harut Chittelian assured us that they have elbow room. They were asked to study the listing in the city center, He said.

Geocontrol writes in the preamble of its report that it has been Commissioned by CDPQ Infra to perform a technical and analytical analysis of the risks associated with the various underground roads in downtown Montreal on two lanes, avenue René Levesque and avenue Saint Antoine..

According to Harut Shetilian, All the track variations that deviate from René-Lévesque severely punish passengers.

He argues that it is a question of success or not. These choices led to the dismantling of other networks. Experts considered scenarios south of Rene Levsk that did not work.

Risks of other underground scenarios

This scenario is not possible, according to AECOM-Systra.

Photo: CDPQ Infra

Scenario under René-Lévesque, between the orange and yellow lines, with an exit to the east of CPCanadian Pacific, is considered impractical, according to Aecom-Systra.

Failure to respect the safety clearances of the yellow line, the danger of tunnel stability, the danger of landing under the tracks CPCanadian Pacific Among the risks mentioned.

Altogether, the average and maximum risk is more than 3,590 metres, or 70% of the road is underground.

Harut Chittelian emphasizes that passing between the lines is fraught with danger. It is a game of odds where the chances of making mistakes are very high. It is almost certain.

It is not a matter of not wanting to take risks. From what we know, it would be irresponsible to recommend this project in this form.

In this same segment, Geocontrol adds that interruptions in the metro during construction will be inevitable.

A decrease in the number of passengers?

For the idea of ​​going under the yellow line, it first represents the risk of equipment failure. The Technoparc tunneling machine has been out for nine months, and the ground is the same, says Chitilian. There was a broken head of the machine. If it happens in the area of ​​the Jacques-Cartier bridge, at a great depth, it is a very precarious situation.

The transition zone will also be impassable at a distance of approximately 500 metres, along Rue Notre Dame.

The other risk is operational: the expected decline in the number of passengers. CDPQ Infra invited Steer Davis Gleave to assess the number of visitors to the eastern REM region. In this scenario, the Labelle station, which is connected to Berri-UQAM, would be at a depth of 40 metres, which could cause an additional travel time of approximately six minutes to reach it. The expected decrease in the number of passengers at this terminal will be 56.5%, according to a related document from CDPQ Infra.

sagging risks

Among the effects associated with underground scenarios, CDPQ Infra lists Destabilization of large buildings due to soil stability or subsidence.

However, according to engineer Mark Durand, this is a file misinterpretation of studies. Aecom-Systra does not mention the risk of sagging. Geocontrol refers to it in relation to municipal infrastructure (sewers and canals) and railways in CPCanadian Pacific.

Harut Shettelian says they don’t mention the buildings, but they say these are risks inherent in changing the soil.

M. Durand notes that CDPQ Infra Widely emphasizes negative elements. But Géocontrol does not refer to impossibilities. They mention the difficulties that need to be solved.

According to Mr. Chitilian, In order to maintain the adequacy of the project size and the possibility of contracting, there are choices that have been made. With the continuous efforts of our architects, there is a possibility to integrate structures.

This part is in the hands of a panel of 15 interdisciplinary experts who must submit their report before the end of the fall.