Réseau express métropolitain
On 13 January 2015, Quebec Premier Philippe Couillard and Michael Sabia, CEO of Caisse de dépôt et placement du Québec (CDPQ), agreed to a partnership in which the Crown corporation could assume financing for major transportation projects in the province, with $7.4billion planned to be spent on infrastructure from 2014 to 2024. Two of these projects were the South Shore Line and the Train de l'Ouest toward the West Island, which eventually merged to become the core of the REM project. On 22 April 2016, Sabia and Montreal Mayor Denis Coderre unveiled the project, then known as the Réseau électrique métropolitain, to the media. The estimated completion date for the first portion of the system was December 2020. On 22 June 2016, CDPQ Infra published two requests for qualification: one for the engineering, procurement and construction contract and the other for the rolling stock, systems, operation, and maintenance. The estimated value of the two contracts are $4billion and $1.5billion respectively. On 25 November 2016, CDPQ Infra announced the addition of three new stations to the project. These new stations—Central Station, McGill, and Édouard-Montpetit—would improve downtown Montreal service by integrating the REM with the Metro system through connections to the Orange, Green and Blue Lines. Included with news of the 3 new stations was an increased price tag of $5.9billion for the entire project. On 15 June 2017, the Government of Canada pledged $1.28billion to finance the project, completing the financing of the project. Construction on the project was announced as starting at the end of 2017. On 1 December 2017, the CDPQ extended the tender process on the project to the end of January 2018, citing a need for additional discussions with the bidders. On 28 June 2016, CDPQ Infra launched two public tenders in parallel: one for "Engineering, Procurement and Construction" (EPC, or "Ingénierie, Approvisionnement et Construction des infrastructures" (IAC) in French), and a second, for "Rolling Stock, Systems and Operation and Maintenance Services" (RSSOM, or "Fourniture du Matériel Roulant, de Systèmes de conduite automatique et de Services d'Exploitation et de Maintenance" (MRSEM) in French). Following a prequalification phase, the Caisse's subsidiary announced, on 10 November 2016, the qualified candidates that would be allowed to submit a bid:

According to "LaPresse", final bids were submitted to CDPQ Infra on 27 October 2017. On 10 November 2017, the date of the planned announcement of the selected contractors, the procurement process was "postponed indefinitely" to provide more time for analysis and evaluation of the bids received. On 8 February 2018, CDPQ Infra finally announced its selection: "Groupe NouvLR" consortium for the EPC contract (SNC-Lavalin Grands Projets, Dragados, Aecon, Pomerleau, EBC and AECOM) and the "Groupe des Partenaires pour la Mobilité des Montréalais" for the RSSOM contract (Alstom and SNC-Lavalin O&M). The contracts' value is estimated to be around $6.3billion, of which approximately 80% is for the EPC contract. Preparatory work began in late March 2018. On 12 April 2018, the project broke ground officially. In December 2019, CDPQ revised the capital cost of the project to $6.5billion, an increase of $230million. In November 2020, a disruption from an "unexpected" explosion during the renovation of the Mont Royal Tunnel, likely caused by century-old explosives, delayed the opening of the central section of the REM from 2022 to 2023. In June 2021, CDPQ updated the project costs to $6.9billion, an increase of $350million, citing impacts from the COVID-19 pandemic in Montreal. The primary route follows the Mount Royal Tunnel, where new underground stations are being built to connect with the existing and Metro stations. A new connection to the Mascouche commuter rail line will be built near the A-40 at the Côte-de-Liesse station to allow this line that previously used the tunnel to have access to downtown. Southeast from Central Station, the line will follow existing rail lines until Marc-Cantin Street, where it will transition to an elevated guideway and cross to Nuns' Island, and then use a rail deck constructed on the new Champlain Bridge to cross the St. Lawrence. Three stations in Brossard on the South Shore are being built: Panama, connecting to the existing bus terminal; Du Quartier, directly connected to the DIX30 commercial district; and Brossard, a future bus terminus. The northwest branch will be a direct conversion of the existing Deux-Montagnes line, with a doubling of the tracks beyond Bois-Franc station. On the West Island, a new airport branch will separate near the A-13, with a stop in Technoparc Saint-Laurent before terminating at Montréal–Pierre Elliott Trudeau International Airport. The other branch will follow an existing freight rail spur through Pointe-Claire, then follow the Quebec A-40 alignment just east of St-Jean Boulevard and continue through Kirkland before ending in Sainte-Anne-de-Bellevue. In the city centre, three stations are being built to connect with existing Metro lines: McGill will connect with the Green Line, Édouard-Montpetit will connect with the Blue Line, and Bonaventure Gare Centrale will connect with the Orange Line. The REM will consist of 26 stations on three branches. Twelve of these stations are on the former suburban Deux-Montagnes line and will become part of the REM after being converted to rapid transit standards. Several have received new names since the project's inception. All stations on the main branch of the Réseau express métropolitain are projected to have a train frequency of 2.5 minutes during rush hour and every 5 minutes otherwise, both towards Brossard station and towards the three different branches. Stations on the Deux-Montagnes branch are projected to run every five minutes during rush hour, and every fifteen minutes otherwise. The Anse-à-l'Orme (formerly Sainte-Anne-de-Bellevue) branch of the Réseau express métropolitain is projected to run every ten minutes during rush hour, and every fifteen minutes otherwise. The Airport branch of the Réseau express métropolitain is projected to run every ten minutes during rush hour, and every fifteen minutes otherwise. In a report prepared by the Bureau d'audiences publiques sur l'environnement (BAPE) and released on 20 January 2017, the project was criticized for failing to provide crucial information on the project's financial model, environmental impact, as well as the impact on ridership levels throughout the public transit network across Montreal. Without such information, the BAPE declared that it was "premature to authorize the approval of this project". The BAPE also stated that CDPQ Infra had not met its obligations for transparency, as it had failed to provide information in a timely fashion on the ridership levels of the REM's three branches. The CDPQ Infra was also reproached for not studying the impact of the REM on existing public transit authorities. CDPQ Infra was criticized for not being able to answer questions like how much tickets would cost, whether municipalities on the REM would themselves have to pay for the necessary infrastructure for access to it, and whether municipalities would also have to contribute to the REM's operation. A lawsuit filed by Coalition Climat further alleged that the REM project violated federalism for a lack of federal assessment of the potential harm to citizens' environmental rights by its potential contribution to noise pollution and urban heat islands. The lawsuit was dismissed by the Quebec Superior Court on 13 December 2017. Another controversy occurred in November 2019, when Montreal mayor Valerie Plante proposed naming Griffintown's REM station after controversial politician Bernard Landry, sparking a backlash from the city's Irish community. As a compromise, the station was named , which still proved controversial. On 20 May 2019, the Quebec provincial government announced that they had requested CDPQi to study two REM extensions. The government also made a request to determine the best electrified transit system to be put in place for the Montreal East Island, with the possibility of it being a new REM line. The proposal became the REM de l'Est Project. The federal government also requested the Canadian Infrastructure Bank study a possible extension of the REM to Dorval train station. The city of Montreal requested two stations instead of one station at Bassin Peel. Mayor Valérie Plante announced funding for the West branch of the "Pink Line". This branch would be a continuation of a REM line, if it is the technology chosen by the CDPQi. The REM would be extended nearly to Carrefour Laval from Du Ruisseau station. The REM would be extended nearly to Chambly and St-Jean-sur-Richelieu from Brossard station. An extra station would be added at the Dorval train station to connect with Exo and Via Rail trains. This station would be about a extension from the Airport station. This station would be added between and stations. The "REM de l'Est" is a planned second REM line which would be long. Announced in 2020, it would use the existing REM technology but not connect directly to the first section of the network. Beginning at Robert-Bourassa, the line would run east on an elevated guideway along the banks of the St. Lawrence River until St-Clément, where it would turn north and split into two branches: The REM de l'Est would add 23 new stations: If the REM technology is chosen, this branch would connect Lachine to Downtown Montreal as an extension of the REM de L'Est.
History
The Réseau express métropolitain (REM; ) is a light metro rapid transit system under construction in Greater Montreal, Quebec, Canada. The light metro rail system is projected to cost $6.9billion. It will be independent of—but connected to—the existing Montreal Metro, operated by the STM. The first section between Brossard and Central Station is expected to open on December 1, 2022.