MARÍA GÓMEZ BRAVO | Tungsteno

Estación Atlántida, located about 45 kilometers from Montevideo, Uruguay, was a small settlement that grew up around the railway in the late 19th century. In the 1950s, a committee of local Catholics from the nearby seaside resort of Atlántida, including Alberto Giudice and his wife, Adela Urioste, decided to build a church to serve the community. They brought the proposal to engineer Eladio Dieste, with the intention of constructing a simple place of worship at a cost comparable to that of an industrial building. Dieste, however, had other ideas. He designed a brick church with undulating walls and a roof with continuous curves that would be recognized as a UNESCO World Heritage Site decades later.

How geometry creates strength

By the time he began working on the church in Atlántida, Dieste (1917–2000) had already spent over a decade exploring the potential of cerámica armada, or reinforced brick masonry. He studied civil engineering at the University of the Republic in Uruguay and began his professional career at a time when reinforced concrete was transforming architecture. However, Dieste saw brick, a traditional and widely available material in his country, as an opportunity for experimentation.

One of his first challenges came with the Berlingieri House in Punta Ballena, designed in 1946 by Catalan architect Antoni Bonet, who had gone into exile in Argentina following the Spanish Civil War. Bonet had originally planned to use reinforced concrete vaults, but they would have been costly to construct. Dieste proposed using steel-reinforced brickwork instead, a solution that combined the compressive strength of brick with steel's ability to withstand tensile forces.

Engineer Eladio Dieste saw brick, a traditional and widely available material in his country, as an opportunity for experimentation. Credit: Structures by Design: R.Whitehead.

That experience sparked a line of research that Dieste would pursue throughout the rest of his career. The Uruguayan engineer studied how curved surfaces could increase structural strength while reducing the amount of material needed for construction. Over time, he applied these principles to factories, warehouses, and agricultural facilities. One example is the Young grain silo, which was designed to store grain beneath reinforced brick vaults.

The Atlántida church commission also held personal significance for Dieste. A man of deep Catholic faith, he wanted to create a gathering place for a working-class community of modest means. Although the budget was limited, Dieste saw these constraints as an opportunity to develop an architectural approach that reflected both the community's needs and his own beliefs.

The Church of Christ the Worker in Atlántida, Uruguay, is notable for its undulating brick walls. It was designated a UNESCO World Heritage Site in 2021. Credit: PABLO PORCIUNCULA / Colaborador.

A church built with curves

Construction of the Church of Christ the Worker and Our Lady of Lourdes in Atlántida began in 1958. Dieste designed the single-nave church with undulating walls that support a reinforced brick roof. These curves strengthened the structure, eliminating the need for interior columns and giving the building its distinctive character. Light filtered through small openings, accentuating the undulations of the exposed brick walls and creating an interior quite unlike that of conventional churches.

This approach to church design also reflected modern ideas in religious architecture. According to architect Mary Méndez in Divinas piedras. Arquitectura y catolicismo en Uruguay (1950–1965), one of Dieste's sources of inspiration was the Notre-Dame-du-Haut Chapel in Ronchamp, designed by Le Corbusier. However, Dieste had to adapt his ideas to the needs of a small Uruguayan community and the constraints of a limited budget.

Méndez notes that Dieste visited the construction site several times a week to personally supervise the work and even consulted Uruguayan architect Justino Serralta, who had worked with Le Corbusier in France, about certain design decisions. This experience would come to hold a special place in Dieste’s career. “The church in Atlántida was my great school of architecture,” he would later acknowledge.

The bell tower of the Church of Christ the Worker in Atlántida, Uruguay, is a cylindrical structure made of openwork brickwork that Dieste ordered demolished and rebuilt when it had already reached a height of five meters. Credit: PABLO PORCIUNCULA / Colaborador.

His meticulous attention to detail was particularly evident during construction of the bell tower. When the tower had reached a height of about five meters, he ordered it demolished because he was dissatisfied with the arrangement of the bricks. This meant starting over, despite the project's financial difficulties. Dieste ultimately waived his fees, and his firm lost money on the project.

The rebuilt bell tower stands beside the church as a cylindrical structure of openwork brickwork. Dieste, who had converted to Catholicism as an adult, also wanted to create a closer connection between worshippers and the altar. To achieve this, he reduced the difference in floor level between the sanctuary and the nave and eliminated the traditional railing that separated them. He placed the baptistery underground and made it accessible from outside via a staircase. The descent into this dimly lit space and the subsequent ascent into the church symbolize baptism and entry into the Christian community. Some of these design choices anticipated the liturgical reforms introduced by the Second Vatican Council, which began in 1962.

The church's distinctive design soon attracted attention beyond Uruguay. In 1961, it was featured in specialist publications in Spain, France, and the United Kingdom. In 2021, UNESCO added it to the World Heritage List, highlighting its innovative use of reinforced brickwork and the relationship between its structural solutions, architectural design, and efficient use of resources.

The challenge of spanning 50 meters without columns

For years, Dieste had applied his research on reinforced brick masonry to factories and other industrial buildings. In 1975, Uruguay's National Ports Administration issued a call for bids to rebuild an old, fire-damaged warehouse at the Port of Montevideo. The tender called for demolishing the warehouse and constructing a new one, but Dieste offered an alternative.

The building still had its 19th-century masonry walls, which Dieste decided to preserve. His proposal involved reinforcing the existing structure and constructing a roof capable of spanning 50 meters without intermediate columns, leaving the space unobstructed for handling and storing goods. This solution would also reduce reconstruction costs.

The reinforced brick vaults of the Julio Herrera y Obes warehouse in Montevideo span 50 meters without intermediate columns. Credit: Joerg Boethling / Alamy Stock.

To accomplish this, Dieste designed 14 double-curvature vaults made of hollow bricks. According to documentation on the Julio Herrera y Obes warehouse, he had never before achieved such a large span between supports using this system. The construction work, carried out between October 1977 and May 1979, returned approximately 4,200 square meters of space to port operations.

The reconstruction required reinforcing the foundations and the original masonry walls to support the new roof. Glazed sections were installed between the vaults to allow natural light to enter. The project preserved the proportions and some of the architectural character of the original warehouse.

In 2016, the warehouse was designated a National Historic Monument of Uruguay. Beneath Dieste's vaults, the 19th-century walls that survived the fire still stand.

Tungsteno is a journalistic laboratory that explores the essence of innovation.

María Gómez Bravo | Tungsteno

In their search for more space, cities first reached skyward. Skyscrapers and landmark towers reshaped skylines and often became symbols of major capitals. Yet a quieter revolution was also taking place underground. It began with a practical aim: moving the infrastructure that keeps a city running beneath its streets. First came sewers and water mains, followed by railways, subway lines, utility cables, parking garages, and even roads.

As land at the surface becomes scarcer, the space below is increasingly valuable. Every new tunnel, cable or facility must fit among the infrastructure already there without blocking what future projects may require. Yet pressure on surface land is only part of the story. Geology, climate, and other local conditions also shape the way cities develop underground.

A City Carved Out of Rock

The granite bedrock beneath much of Helsinki has helped shape the city’s underground development. For decades, it has been excavated to create tunnels, parking garages, energy facilities, and sports venues. Helsinki has made systematic use of its distinctive geology since the 1960s. By the time it began drafting its first dedicated underground plan, around nine million cubic meters of rock had already been excavated for some 400 facilities and tunnels. 

Many of these spaces have a dual role. In everyday life, underground facilities house swimming pools, sports centers, and other recreational spaces carved out of the bedrock. In an emergency, they can also serve as civil defense shelters. Shared tunnels carry district-heating and cooling pipes, high-voltage power cables, and telecommunications networks, which together extended for around 300 kilometers when the plan was drawn up.

The underground swimming pool in Itäkeskus is located in bedrock 50 meters below the surface, inside one of Helsinki’s civil defense shelters that has been adapted for everyday use. Credit: ALESSANDRO RAMPAZZO/AFP via Getty Images.

As demand for underground space grew, Helsinki had to consider not only where to build new facilities, but also which parts of the bedrock should be left untouched for future use. The result was the Underground Resources and Master Plan, which mapped existing and planned caverns, facilities, and tunnels, while reserving space for long-term projects. The first plan identified 40 new areas as rock reserves and more than 100 sites for future construction. Ilkka Vähäaho, who headed Helsinki’s geotechnical division for many years, has explained that the rapid expansion of underground construction since the beginning of this century has made it increasingly necessary to manage where excavation takes place.

Helsinki’s first underground plan put it simply: bedrock can be excavated only once. Buildings can be replaced and plots of land repurposed, but caverns carved into the rock are permanent and may obstruct future infrastructure. Helsinki therefore began planning not only what to build underground, but also the empty space that would need to remain available.

A Shield Against Winter

In Montreal, Canada, winter shapes not only how people get around, but also how they use the city. Beneath its streets, a network of pedestrian walkways links offices, universities, hotels, shopping centers, and other buildings without requiring people to step outside. Used by about 500,000 people a day, this underground city allows residents and visitors to travel across much of downtown sheltered from the cold.

Yet the nearly 32 kilometers of walkways that make up RÉSO, Montreal’s underground pedestrian network, were not originally built as a response to the climate. The network began to take shape around Place Ville Marie between 1962 and 1967, expanding alongside major downtown property developments and the growing metro system, particularly in the years leading up to Expo 67.

The Montreal Trust shopping center is part of RÉSO, the underground network that connects buildings, stores, hotels, and metro stations in downtown Montreal via nearly 32 kilometers of walkways. Credit: Pascal QUITTEMELLE/Gamma-Rapho via Getty Images.

There was no single master plan. Instead, connections were added over the decades as new buildings were incorporated into the system. This organic growth turned this underground network into an extraordinary asset for both the downtown economy and the everyday mobility of its residents during the coldest months. Today, RÉSO is so woven into the life of the city that it is hard to separate its economic role from its practical value as a way of getting around.

Cold weather does affect how people move around Montreal. A study by Luis F. Miranda-Moreno and Aleksiina Lahti found that outdoor pedestrian traffic declines in winter, with temperature, humidity, wind, and precipitation all influencing the decision to walk. Yet RÉSO has become so embedded in the workings of downtown that the weather outside makes surprisingly little difference to how residents use it. 

An analysis by Professor John Zacharias on underground pedestrian trips in the city found that weather has no impact on the distance people walked or the proportion of the journey spent underground. The starting point mattered far more. What began as a series of separate connections has become part of the everyday experience of crossing downtown Montreal, regardless of the weather.

150 Meters Beneath Singapore

Beneath Jurong Island, off the coast of Singapore, five enormous caverns lie hidden about 150 meters below ground. The Jurong Rock Caverns can store up to 1.47 million cubic meters of liquid hydrocarbons for Singapore’s energy and chemical industries. Building them freed about 60 hectares at the surface for other industrial activities. In a country with a land area of just over 730 square kilometers, that is a significant gain.

For decades, Singapore has been waging a battle to create room in a city-state with little land to spare. It has reclaimed land from the sea, built upward, and increasingly looked below ground. Mining engineer Yingxin Zhou captured the idea vividly at the 2018 World Urban Forum: “Singapore doesn’t have gold, oil, or diamonds. But we mine something equally precious: space.”

In total, Singapore already has about 300 kilometers of tunnels and plans to add a further 60 kilometers over the next decade, according to the Master Plan 2025. Credit: John Seaton Callahan.

The Jurong Rock Caverns are perhaps the most spectacular manifestation of Singapore’s search for underground space, but much of this transformation remains out of sight. On the main island, the underground levels closest to the surface accommodate shops, parking garages, services, and pedestrian links. Deeper down are rail lines, roads, and networks for water, sewer, and electricity. In total, Singapore already has about 300 kilometers of tunnels and plans to add a further 60 kilometers over the next decade, according to the Master Plan 2025.

As Singapore has made increasing use of its subsurface, long-term planning has become necessary. In 2007, the government established a dedicated inter-agency task force. Three years later, underground development was incorporated into the country’s economic strategy, as Zhou and Jian Zhao describe in a study published in Tunnelling and Underground Space Technology. The Master Plan 2025 now explores new possibilities, from storage caverns and utility tunnels to energy infrastructure, while reserving room for future needs.

Creating space at the surface can also lead to costs underground. Subterranean spaces require lighting, ventilation, and often dehumidification. A study published in Sustainable Cities and Society also identified potential benefits associated with transportation, more compact land use, infrastructure, and geothermal energy. Depth alone does not make a project sustainable. What matters is what is moved underground, how much room that creates above ground, and how long the space can be put to good use.

Tungsteno is a journalistic laboratory that explores the essence of innovation.

Artificial intelligence enables us to develop infrastructure capable of understanding what is happening within it, anticipating potential risks, and helping us make better decisions.

With this vision in mind, we are developing TunelIA, an innovation project funded through the REDes call for proposals by Spain’s Ministry for the Ecological Transition and the Demographic Challenge. The project begins in October 2026 and runs until December 2027.

“With TunelIA, we want to take a step forward in how we look after our infrastructure, moving from observing what has already happened to anticipating what could happen,” says Antonio Ramírez, Innovation Director at Sacyr Concesiones.

TunelIA combines artificial intelligence, advanced sensors, predictive models, and digital twins across two complementary areas.
The first focuses on intelligent ventilation management and fire-related risks. The second applies artificial intelligence to tunnel structural maintenance.

Intelligent ventilation

Tunnels are complex infrastructure assets that incorporate a range of ventilation, lighting, safety, and control systems. Managing them effectively is particularly important in critical situations, such as accidents or fires, but also in day-to-day operations, when we need to maintain air quality while using energy efficiently.

To achieve this, we collect information from sensors and the SCADA system, which monitors and controls industrial processes remotely and in real time, together with data on traffic, weather, maintenance, and tunnel characteristics.

“One of TunelIA’s main objectives is to reduce electricity consumption from ventilation by up to 20%. The project will also be able to predict potential critical situations inside the tunnel, such as a fire, up to 48 hours in advance, and simulate these scenarios before they occur to determine the most effective response and minimize risks to infrastructure users,” explains Antonio Ramírez.

The AI models will analyze this information to optimize fan operation, predict how factors such as gas accumulation and smoke propagation will evolve, and support a more effective response to different scenarios.

This will enable us to combine energy efficiency, prevention, and safety in a single tool.

Improving tunnel maintenance

The project’s second area focuses on tunnel structural maintenance, using a platform equipped with LiDAR sensors and thermal and RGB cameras.
These technologies will enable us to automatically detect cracks, moisture, spalling, detachments, corrosion, efflorescence, and other defects.

The data will be integrated into a digital platform showing the location and severity of each defect, helping us prioritize interventions and carry out faster, more objective, and traceable inspections. This can reduce inspection costs compared with traditional methods.

We are working on this solution with Sener Mobility, which contributes its technological expertise and DITer device. DITer provides the basis for the further development of automated tunnel inspection. The solution will be validated under real-world conditions, with its results compared against those obtained using traditional methods.

If validation is successful, the solution could gradually be adapted to other types of underground infrastructure and deployed in other markets where we operate.

Sacyr has 66 kilometers of tunnels under concession. The Buga-Buenaventura route in Colombia, which includes 17 tunnels, will take part in the pilot.