Over the past month, there has been a lot of drama surrounding the proposed Réseau express métropolitain de l'Est, set to be yet another landmark Montreal transit projects. And as with any landmark Montreal transit project, there are bound to be hiccups.\nRecently, the REM de l'Est has stirred up some controversy, reportedly leading two architectural firms to quit the project. Here's what's happening.\nEditor's Choice: Can Quebec Festivals Actually Happen This Summer? Here's What Dr. Arruda Had To Say\n\n\nWhat's the controversy with the REM de l'Est?\nAt issue is a proposal to run the REM de l'Est lines along rue Notre-Dame Est and boulevard René-Lévesque via an elevated track. The concerns of residents have been widely reported in the media.\nSome — including, according to reports, Mayor Valérie Plante — have called for the line to run underground, instead, to minimize disruption along these corridors.\nAccording to CDPQ Infra, however, it's not so easy.\nA study (published in a February progress report) that evaluated six possible underground routes downtown identified several challenges the company called "fatal."\nCurrent underground infrastructures like the metro and sewer lines not only pose construction challenges, CDPQ Infra found, but also serious threats to nearby structures.\nIn some scenarios, new underground tunnels could potentially pose a "risk of collapse" for neighbouring buildings, the study says.\nAccording to Jean-Vincent Lacroix, communications director at CDPQ Infra, the "six underground insertion scenarios [proved] to be technically unviable in terms of physical constraints and identified critical risks."\n\nWhat are the options for the future?\nCDPQ Infra also studied the possibility of installing a tramway, instead, but argued in a December presentation that it wouldn't have the capacity, speed or flexibility necessary to meet the needs of riders and compete with other modes of transport.\nAs for next steps, the company plans to get more input from experts and the public on the design of the network.\nThis month, it's putting together an advisory committee whose mission "will be to make recommendations regarding the network’s architectural quality and its urban integration upstream of design," according to a February news release.\nCDPQ Infra says the committee will be "made up of independent experts [...] from various fields including urban development, architecture, heritage, the arts and the business community."\n"It's important to remember that the integration of the REM de l’Est must be exemplary in terms of urban integration and architecture, inspired by best practices from around the world," Lacroix said in a statement.\nThe company also tells MTL Blog that it plans to hold consultations between April and June with residents in communities that the REM de l'Est will cross.\n\nWhen can we expect the REM de l'Est?\n"Technical and environmental studies" are already underway, the news release states.\nAccording to a timeline in the February progress report, the project will be submitted to the Bureau d'audiences publiques sur l'environnement in "early 2022."\nThe BAPE will then issue an "environmental decree."\nCDPQ Infra aims to break ground in 2023 and begin service in 2029.*\nThe REM de l'Est project aims to accommodate some 133,000 passengers per day.\n\n*This article has been updated.