A 98-meter-long tunnel boring machine called Mayrit has already excavated more than 670 meters of tunnel and removed almost 47,000 cubic meters of earth in just 55 days under the streets of Madrid, in the expansion of Line 11 of the metro that will create the great underground diagonal of the Spanish capital.

Written by Bruno Teles

Published on 03/06/2026 at 15:44

Updated on 03/06/2026 at 15:45

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While the city follows its routine on the surface, a machine the size of a football field advances silently below, installing concrete rings as it digs. And there is a curious detail: the mountain of earth removed does not become waste, but finds a destination that few imagine.

A 98-meter-long tunnel boring machine called Mayrit has already excavated more than 670 meters of tunnel and removed almost 47,000 cubic meters of earth in just 55 days under the streets of Madrid. The gigantic machine is working on the expansion of Metro Line 11, a project that aims to create the so-called great underground diagonal of the Spanish capital, connecting distant neighborhoods without passing through the congested city center.

The data was released by the Community of Madrid, the regional government responsible for the project, based on information from the Secretariat of Housing, Transport, and Infrastructure. The machine began drilling on March 26, 2026, and is the first tunnel boring machine to operate in Madrid’s subsoil in 15 years. It is worth noting that the images that circulated with the news on some websites were generated by artificial intelligence, not real photos of the work, but the numbers and the progress of the project are official and can be verified with the regional government.

The impressive numbers of the tunnel boring machine Mayrit

The tunnel boring machine Mayrit, 98 m long, has already excavated more than 670 m of tunnel and removed almost 47,000 m³ of earth in 55 days in the expansion of Metro Line 11 in Madrid. — The machine’s performance in the first few weeks drew attention.

In 55 days of work, the tunnel boring machine Mayrit, which is 98 meters long and weighs about 1,500 tons, advanced 672.6 meters from the future Comillas station towards Madrid Río, removed 46,676.2 cubic meters of earth, and installed 389 concrete rings that support the tunnel as it is excavated.

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The curious fate of the excavated earth

One of the most interesting aspects of the project is what happens to all the material removed.

The thousands of tons of earth extracted from the subsoil of Madrid are not simply discarded: they are used to restore about half a dozen former mining operations and recover a landfill that is now deactivated in the region, an example of waste reuse.

To handle this transport, a fleet of approximately 150 trucks operates continuously, taking the sediments to the planned destinations.

The earth exits the tunnel via conveyor belts and passes through large capacity pits before being transported.

This logistics shows how a large underground project needs to think not only about the excavation itself but also about the environmental management of everything that is removed from the ground.

How the tunnel is assembled from the inside

The Mayrit tunnel boring machine, 98 m long, has already excavated more than 670 m of tunnel and removed almost 47,000 m³ of earth in 55 days in the expansion of Line 11 of the Madrid metro. — The construction of the tunnel follows an industrialized and precise process.

The concrete pieces that form the tunnel walls, called segments, are manufactured in a specific plant in Noblejas, in the province of Toledo, where about 50 workers produce 42 segments per day, equivalent to six complete rings, which are then transported to the construction site by special heavy load vehicles.

Each complete structural ring is formed by the exact joining of seven concrete pieces, fitted underground by the tunnel boring machine itself.

This model of industrialized construction, in which the pieces are produced in a factory and only assembled on site, helps to speed up deadlines and reduce unforeseen events.

The production of the segments, in fact, began back in September 2025, even before the machine arrived in Spain from Germany.

The great underground diagonal of Madrid

The ultimate goal of the project is to transform mobility in the Spanish capital.

The expansion of Line 11 aims to create a large underground diagonal that, when fully completed, will connect the regions of Cuatro Vientos and Valdebebas over 33.5 kilometers, allowing one to cross Madrid from one end to the other in just over an hour, without passing through the congested center.

The current section, under excavation, will connect the Comillas station in the Carabanchel neighborhood to points like Atocha and Conde de Casal, without the need for transfers on the overloaded Line 6.

The proposal is to reduce travel time for users, decrease congestion and air pollution, offering a more efficient public transport alternative for those living and moving around the city.

Deadlines, stages, and investment

The project progresses through well-defined phases and with a significant budget.

The forecast is that the section between Comillas and Madrid Río will be completed in June 2026, when the tunnel boring machine will undergo a technical review of about two weeks before heading towards Palos de la Frontera, Atocha, and finally Conde de Casal, ending this phase expected by the end of 2027, if deadlines are met.

The total investment allocated for this modernization exceeds 739 million euros, of which the majority, about 586 million, is dedicated to the execution of the tunnel and five new stations.

The section under construction, approximately 5.5 kilometers, will require the installation of more than 3,000 concrete rings.

It is a high investment, but the regional government presents it as a strategic bet to transform the way people move around the capital.

What this has to do with Brazil

Projects like this are not exclusive to Europe and resonate with the Brazilian reality.

Brazil also uses large tunnel boring machines in metro projects, especially in São Paulo, where similar machines have been employed in line expansions to tackle the same urban mobility and congestion challenges that afflict major capitals worldwide.

Following international reference projects, like Madrid’s, helps understand the technologies and construction methods that can be applied here.

Industrialized construction, the use of tunnel boring machines, and the reuse of excavated material are global trends in infrastructure engineering, and the advancement of Mayrit is a good example of how technology is making these large projects faster and more efficient.

The advance of the Mayrit tunnel boring machine under the streets of Madrid is an impressive demonstration of how modern engineering is capable of transforming a city from the underground, with colossal machines, industrialized construction, and even concern for the destination of the excavated soil.

More than grand numbers, the project represents a bet on the urban mobility of the future, with the promise of connecting neighborhoods and making life easier for millions of people.

If the deadlines are met, Madrid’s great underground diagonal will be a milestone worth following, even as inspiration for Brazil.

And you, did you have any idea of the size and complexity of the machines that build the subway tunnels? What did you think of the destination given to the excavated soil and this project under the streets of Madrid? Leave your comment, share your opinion on public transport and urban mobility, and share the article with those interested in engineering, construction, and technology.

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While the city follows its routine on the surface, a machine the size of a football field advances silently below, installing concrete rings as it digs. And there is a curious detail: the mountain of earth removed does not become waste, but finds a destination that few imagine.

The impressive numbers of the tunnel boring machine Mayrit

The curious fate of the excavated earth

How the tunnel is assembled from the inside

The great underground diagonal of Madrid

Deadlines, stages, and investment

What this has to do with Brazil

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While the city follows its routine on the surface, a machine the size of a football field advances silently below, installing concrete rings as it digs. And there is a curious detail: the mountain of earth removed does not become waste, but finds a destination that few imagine.

The impressive numbers of the tunnel boring machine Mayrit

The curious fate of the excavated earth

How the tunnel is assembled from the inside

The great underground diagonal of Madrid

Deadlines, stages, and investment

What this has to do with Brazil

A giant printer called the “Ferrari” of concrete has landed in Latin America and can already build a 120-square-meter house in just 48 hours, making the traditional construction site look like something from the last century.

Brazil will harvest a record crop of up to 357 million tons of grains, but it does not have the capacity to store a large part of it. The storage deficit has reached the highest level in history and is equivalent to almost the entire production of Argentina.

Four times faster than the Concorde, capable of taking passengers from New York to London in less than an hour at Mach 5.5, and with an engine that switches from turbojet to ramjet mid-flight at Mach 3.5, the Hermeus Quarterhorse went from paper to its first flight in just 19 months.

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