The country’s two largest metro projects get off the drawing board with billion-dollar investments, cutting-edge engineering under Guanabara Bay, and the promise of transforming the commute of millions of passengers.

“We will connect Rio to São Gonçalo and Niterói with high-capacity, comfortable transport. It is a long-held dream that is now beginning to materialize.” These words, spoken by Rio de Janeiro’s State Secretary of Transportation, Washington Reis, during the presentation of the Metro Master Plan, represent a tangible shift in the country’s urban planning.

This is not an empty election-year announcement, but a project with 22 km of extension, 15 stations, and an estimated cost of R$14.6 billion just to build Line 3, connecting Praça 15 in the city center to Guaxindiba in São Gonçalo.

The most striking aspect of the Rio de Janeiro project is the excavation of Brazil’s first underwater metro tunnel beneath Guanabara Bay. There will be 3 km of excavation through rock and soft soil between Praça 15 and Cantareira in Niterói, using a large-diameter tunnel boring machine (TBM) to overcome water pressure and the complex geology of the bay floor.

As detailed by G1 in coverage of the official announcement, the section will be implemented under a Public-Private Partnership (PPP) regime, with the first tenders scheduled for early 2026. Guaxindiba station will be strategically located near the BR-101 highway to facilitate integration with intercity buses, reducing travel time between Niterói and São Gonçalo from two hours to just 40 minutes.

The project solves a chronic transportation engineering problem in the metropolitan region, where the Rio-Niterói Bridge operates at capacity during peak hours. Line 3 is born with the capacity to serve 650,000 users per day, relieving road transport and creating a high-capacity rail axis with electric traction, third rail, and modern signaling.

While Rio advances over water, São Paulo breaks investment records underground and on elevated tracks. The São Paulo state government approved a budget of R$5.4 billion for 2026, the largest in the history of the São Paulo Metro, for the simultaneous expansion of three strategic lines that weave through the urban fabric of the capital and Greater São Paulo.

The largest volume of resources is concentrated on the Green Line 2, which will gain 13.8 km of new tracks to Guarulhos, with an investment of R$2.59 billion next year alone, as reported by Exame. The project, already over 55% complete on the stretch to Penha, will be the first heavy metro connection between the capital and the state’s second-largest city.

The Silver Line 15, in turn, consolidates São Paulo’s bet on monorail as a solution for medium-capacity corridors. With R$1.03 billion set aside for 2026, the branch will be extended from Ipiranga to Cidade Tiradentes, operating on elevated tracks above the Tamanduateí River Valley and using 19 new trains, 15 of which have already been delivered by the manufacturer.

The Gold Line 17, a 6.7 km branch also on elevated tracks, is finally moving toward the inauguration of the section between Congonhas Airport and Morumbi station, scheduled for March 2026. The route, awaited since the 2014 World Cup, will consume R$836.3 million from the budget and will operate with rubber-tired trains on concrete beams, a typical feature of monorail systems.

The State of São Paulo also announced a total package of R$33 billion in ongoing metro works, with US$425 million raised in international loans for the Green Line 2 and Orange Line 6, as reported by Times Brasil. The funds finance the purchase of 63 new trains, including 44 for the Blue Line 1, Green Line 2, and Red Line 3, which will receive the CBTC system.

The adoption of CBTC represents a leap in operational precision, replacing the old fixed block signaling with continuous communication between trains and the control center via digital radio. This allows trains to run with shorter headways, increasing transport capacity per hour per direction without building new tunnels.

Another planned modernization element is the installation of platform screen doors at new stations, equipment that eliminates the risk of passengers falling onto the tracks and prevents external interference in train operations. Combined with the third rail, which supplies trains with 750 volts of direct current, the São Paulo system approaches the operational standard of the most efficient Asian and European metros.

The financial math behind these projects reveals the magnitude of Brazil’s railway challenge. As pointed out by a report from InvestNews, each kilometer of track costs an average of R$27 million, more than three times the cost of a highway, requiring sophisticated financial engineering and state participation to make long-term returns viable.

In Rio, funding will come from a combination of state, municipal, and BNDES resources, while São Paulo diversifies its sources among multilateral bodies, private banks, and international development agencies. The presence of Chinese capital on the horizon, especially through CRRC, which is preparing a factory in Araraquara to produce trains starting in 2026, adds a relevant geopolitical layer to the resurgence of urban rail in the country.

The two metropolises, with their simultaneous projects, rehearse a revival of metro planning that had been stagnant for nearly a decade. The tunnel under Guanabara Bay and the elevated branches in São Paulo’s eastern zone are not mere civil engineering works: they are interventions that change urban density, land values, and labor productivity in two metropolitan regions that together concentrate more than 30 million inhabitants.