The terrain that characterizes the surroundings of the Sicilian city of Catania is unique due to the omnipresence of Mount Etna. The eruptions over time have shaped a capricious and highly variable subsoil. 

In this environment, we will develop a major railway project: the Metropolitana di Catania expansion, with a budget of nearly 800 million euros. The extension covers almost 14 km of line, of which eight and a half are underground sections of various kinds. This expansion will connect several towns in the metropolitan area.

Ferrovia Circumetnea (FCE), an agency under the Italian Ministry of Infrastructure and Transport, awarded SIS—a permanent consortium formed by Finninc (51%) and Sacyr (49%)—a section between the towns of Misterbianco and Paternò in September 2023, and in December 2024, a complementary section between Monte Po (Catania) and Misterbianco, connecting with the currently operational line.

This project will feature the use of a new and uncommon tunnel boring machine known as the Variable Density TBM (VD-TBM). Only about 20 machines of this type have been ever operated worldwide. 

The handover ceremony for the TBM took place on May 27, with representatives from Herrenknecht (the TBM manufacturer), SIS (Finninc and Sacyr), and FCE (Ferrovia Circumetnea) in attendance.
 

It stands out for its adaptability to the area’s changing geological conditions. Additionally, due to the frequent seismic activity generated by the volcano, it is necessary to comply with strict seismic standards for both permanent and temporary works.

“A few years ago, the city already undertook a metro project using a conventional TBM, and it ran into significant difficulties due to the unfavorable geological conditions”, explains Miguel Ángel Montón, tunnel manager for this project.

“The ground is extremely complex due to its heterogeneity; there are fissures, cavities, and frequent alternations between basaltic rock—lava—and softer soils. Our TBM is highly adaptable to current conditions; its operating mode can be changed on the fly using four different excavation modes, allowing us to respond in real time to the terrain. It is more complex to operate, but offers that flexibility”, Montón adds.

This isn’t the first time that Montón faces this kind of challenge, as he had a similar experience on Line 3 of the Guadalajara Metro (Mexico). “It was more complicated than usual, but not as challenging as this project,” he states.
 

The TBM began manufacturing in August 2024  and operational testing started in May this year.  Disassembly and transport to the construction site are scheduled to begin in June, with arrival expected in July.

The heaviest components will be transported across the Alps using special convoys to the port of Ravenna (Italy), from where they will be shipped to Catania. The smaller components will be transported by truck to across the Strait of Messina to reach Sicily. 

On-site assembly of the machine will take around three months, followed by approximately two weeks of commissioning and testing. Excavation is expected to begin by the end of December or early 2026.

“We will excavate around 5 km of tunnel with this TBM. The initial contract was for 3,200 meters, and with the most recent award, an additional 2 km were added,” Montón explains.

The implementation of infrastructure and services in developing countries is often not particularly easy for companies or institutions from outside the country. And maintaining them isn’t easy either.

There are several important factors to consider when working toward economic, social, and health development in each region.
The first is the existence of a social cohesion structure. “There must be at least a basic social and political structure with a hierarchy and codes of conduct. The political structure must organize resources, distribute them, and promote a development strategy, stability, and future vision,” explains Ignacio Calatayud, president of HumanCoop, an NGO that works in development cooperation in Africa. Their working philosophy approaches community health through a One Health strategy, which aims to sustainably balance and optimize the health of people, animals, and ecosystems through training local personnel and building infrastructure.

“Political instability, corruption, and insecurity create obstacles that make it difficult to operate in a country,” says Calatayud.

Secondly, there must be a communication and energy infrastructure network around areas with water reserves and certain easily exploitable resources. “Cooperation between states to foster development in this area is important. Collaboration between different institutions—from the smallest local governments to the World Bank—is also key to supporting the maintenance of these structures, which attract investment to their countries,” affirms the president of HumanCoop.

 

The third important factor is adaptation to the local culture. NGOs like UPlanet serve as a bridge between technical knowledge—engineering, in this case—and local authorities and funding entities. “We must adapt our knowledge to the local culture. When a Western structure is introduced, there has to be someone with local knowledge to determine whether that technology can be implemented,” explains José Matías Fernández, president of UPlanet.

Volunteers who support organizations like HumanCoop or UPlanet are essential in maintaining water purification plants, self-sustaining agricultural systems, health centers, schools, and more. But without qualified local human capital, those infrastructures or services will fall into decline.
Recently, volunteers from the Sacyr Foundation—mainly engineers—participated in a cooperation project in Bir Mogrein (Mauritania, Africa).

Their goal was to help repair the town’s desalination plant, which is the community’s source of drinking water, improve the electrical installations of health and water infrastructure, develop a sanitation project at one of the schools, and launch a pilot project for drip irrigation using desalinated water—laying the groundwork for the region’s future agricultural project.

Ithar Association's cancer facility under development in Nouackchott, Mauritania

In this regard, a significant obstacle to working toward prosperous infrastructure in developing countries is the lack of human resources capable of managing the technologies, materials, or construction and maintenance techniques. That’s why continuous local human capital training is so important—and why conditions must be created to prevent brain drain.

The lack of cohesion among Western governments often hampers development cooperation in essential areas such as health, food, or industry in underdeveloped countries. “The globalization of Western ideas is declining. Governments are increasingly reluctant to collaborate. Development cooperation and humanitarian aid are two sides of the same coin, but they are not the same,” explains the president of HumanCoop. “We must help these countries, but at the same time, we must sow seeds for future progress. Otherwise, the work you’ve done today won’t be useful for the future, it’ll be just a short-term fix” Calatayud concludes.