Lima completes tunnel excavation for Peru’s first fully underground metro

Excavation has been completed on Lima Metro Line 2, marking a major milestone for Peru’s first fully underground metro system. The breakthrough of the final diaphragm wall at Station 4 completed the planned 27 km of tunnels beneath one of Latin America’s most congested metropolitan areas.

The new line will connect Ate in eastern Lima with Callao, Peru’s main port and airport district. Once operational, it is expected to reduce the journey between Ate and Callao from more than two and a half hours by road to around 45 minutes by metro.

The project is strategically important because it follows one of the capital’s busiest east-west corridors. It will serve residential districts, universities, commercial zones, industrial areas, the Port of Callao and Jorge Chávez International Airport. For millions of residents, the line is expected to improve access to employment, education, healthcare and public services.

Two tunnel boring machines were used to excavate the Line 2 tunnels, each with a cutterhead more than 10 m in diameter. The machines operated at depths greater than 12 m beneath Lima’s streets, allowing tunnel construction to proceed below active roads, buildings and utilities.

Urban metro tunnelling requires strict control of settlement, groundwater, face stability, vibration and shaft construction. In a city such as Lima, where surface traffic is already heavily congested, underground construction can provide high-capacity transport while reducing the long-term need for widening roads or adding more surface infrastructure.

The wider scheme includes Line 2 and a section of Line 4, creating a total of 35 km of underground railway. It will include 35 stations, 36 ventilation and emergency shafts, two depots and interchange connections between the lines. Stations are being delivered through different methods, including cut-and-cover construction and mined cavern works.

With tunnelling complete, the project now moves into the next major phase. Works will focus on track laying, power systems, signalling, ventilation, emergency systems and station completion. This stage is critical because a metro line only becomes operational when the civil works, railway technology and passenger infrastructure are fully integrated.

The completion of tunnel excavation is therefore not the end of the project, but it removes one of the biggest underground construction risks. It confirms that the continuous tunnel route is now physically formed beneath the city.

For Lima, Line 2 represents more than a transport upgrade. It is a structural change in how the city moves. By shifting large passenger flows underground, the project can reduce road congestion, improve travel reliability and connect areas that are currently separated by long and unpredictable journeys.