The success story of Biobío: Electrification of the largest railway bridge in Chile

The new railway bridge over the River Biobío is not only an imposing piece of infrastructure. It represents a profound change in the way thousands of people move, work, and live in the Concepción region. With this work, Chile takes a decisive step towards the modernisation of its railway network, reinforcing sustainable mobility and the role of the Biotrén as the backbone of metropolitan transport.

The previous bridge, in service for more than 133 years, gave way to a 1.8 km-long infrastructure with double electrified track, the largest of its kind in Chile.

The magnitude of this project makes it a benchmark in the region, and ARCA’s role in the electrification of the viaduct underlines how technological innovation can serve social progress. In the following pages you will discover the challenge posed by this work, its most relevant figures, the social impact it will have, and how ARCA provided the critical components that made its electrification possible.

A project with an estimated value of 270 million dollars that not only redefines regional mobility but also marks a milestone for railway engineering in Latin America.

From a centenary bridge to a 21st-century challenge

The original railway bridge over the River Biobío entered service in 1889. For more than a century it fulfilled its function, but over time it became an obsolete and limited infrastructure for the current needs of the Biobío Region.

At the same time, the Concepción region was experiencing sustained growth in the demand for public transport. The Biotrén system was consolidating as the backbone of metropolitan mobility, and with it the pressure on infrastructure unable to meet expectations of safety, efficiency, and sustainability.

The need was clear: to design and build a new bridge with double electrified track, capable of absorbing mixed passenger and freight traffic, ensuring uninterrupted service continuity, and laying the basis for a model of modern, reliable, and sustainable mobility for the coming decades.

The obstacles of the past

• A single operational track, which restricted circulation capacity.
• Safety constraints: in the event of river flooding, traffic had to be halted according to strict protocols.
• High maintenance costs, arising from constant interventions to prolong its service life.

A large-scale engineering work

The new Biobío railway bridge is not only the longest in Chile; it is also one of the most complex infrastructure projects undertaken in the country in recent years.

Its foundations rest on piles between 28 and 46 metres deep, designed to withstand the conditions of the River Biobío, one of the most voluminous rivers in Chile. The main structure is composed of box girders and prefabricated tie beams, assembled on site. At the same time, the civil works included the construction of the Chepe Tunnel, 325 metres long, excavated entirely in rock to connect the viaduct with the existing railway network.

 

A lighter, more efficient and sustainable design

Even in its aesthetic design, there was innovation: in 2024, the ornamentation originally planned for the bridge was revised, opting for a lighter, more efficient, and lower-maintenance alternative, without renouncing its architectural value.

The project also incorporates complementary solutions that make it a benchmark of modern engineering:

• Stormwater drainage systems to increase safety and durability.
• Acoustic screens at the tunnel exit, to reduce noise impact on nearby communities.
• Landscaping works at the accesses, improving the project’s urban integration.
• Redesign of the southern shunting yard to optimise railway operations.

The timeline behind a historic project

Behind the magnitude of the work there is also a journey of planning, engineering, and execution that has spanned almost a decade.

• 2017: Start of the engineering phase, with topographic, bathymetric and seismic risk studies.
• 2019: Presentation and approval of the Environmental Impact Study, including public participation processes in Concepción and San Pedro de la Paz.
• 2022: Official start of construction works on the bridge and Chepe Tunnel.
• 2025: Full commissioning of the new viaduct.

The project in figures

The new railway bridge over the River Biobío is, due to its scope and complexity, one of the largest railway projects in Chile’s recent history. Its numbers speak for themselves:

• 325 metres of the Chepe Tunnel excavated in rock, completing the railway alignment and adding an extra engineering challenge.
• 1.8 km in length, the longest railway bridge in the country, capable of becoming a true mobility corridor for the region.
• 270 million USD investment, a strategic commitment reflecting Chile’s pledge to modernise its railway network.
• 2 electrified tracks designed for mixed passenger and freight traffic, ensuring greater capacity, fluidity, and safety.
• 100 km/h for passengers and 65 km/h for freight, a substantial improvement over the previous bridge, enabling increased speed, frequency, and competitiveness of rail transport.

An unprecedented social impact

The new Biobío bridge is not just a railway infrastructure: it is a lever for social and territorial transformation for the entire Biobío Region.

• Quality of life: Journeys between Concepción, San Pedro de la Paz, and Coronel will be faster, safer, and more frequent, facilitating access to employment, education, and essential services.
• Sustainable mobility: The increased capacity of the Biotrén will enable more inhabitants to choose rail as their daily mode of transport, reducing dependence on private vehicles.
• Environmental sustainability: Fewer private vehicles mean fewer emissions and a firm commitment to cleaner, more efficient public transport.
• Urban development: The project integrates environmental improvements such as acoustic screens, landscaping, and the redesign of the shunting yard, promoting harmonious coexistence with the urban fabric.

This project demonstrates that engineering can be much more than calculation and construction: it can become a tool for social cohesion, economic development, and environmental sustainability.

A project with the community

The Biobío bridge was not only designed to connect banks: from the outset it was conceived as a work that should integrate with the community and respond to its needs.

Citizen participation

In 2019, a process of Citizen Participation (PAC) was carried out in San Pedro de la Paz and Concepción, within the framework of the Environmental Impact Study. This dialogue made it possible to gather local concerns and strengthen social acceptance of the project.

Regional economic impact

The manufacture of the bridge’s beams was undertaken by the Edyce plant, located in the Biobío Region. A decision that not only ensured logistical efficiency but also created jobs and boosted the local economy.

A shared historic milestone

In 2025, the Biotrén crossed the new railway bridge for the first time. The inaugural journey between Coronel and Concepción marked a before and after in the region’s mobility and was celebrated in the presence of the Minister of Transport and Telecommunications, local authorities, and EFE workers.

More than an engineering work, the Biobío has become a project shared with the community, symbolising the union of infrastructure, citizenship, and future.

How ARCA contributed to the largest railway bridge in Chile

In an infrastructure of the magnitude of the new Biobío railway bridge, where passenger and freight traffic converge, the reliability of electrification is key. ARCA contributed with four fundamental elements of the catenary system:

Cantilevers

Cantilevers support and fix the main elements of the catenary, guaranteeing structural stability in a work subjected to great mechanical stress. In the case of the Biobío, their robustness is essential to withstand constant mechanical stresses, wind conditions over the viaduct, and the vibration generated by the passage of passenger and freight trains.

Droppers

The Droppers ensure that the contact wire maintains its precise geometry, a condition indispensable for safe and constant current flow in long-distance services. On a bridge of this scale, the regularity of the wire’s height is key to guaranteeing a stable pantograph-train connection, even at speeds of up to 100 km/h, avoiding jumps or loss of electrical contact.

Compensation devices

They keep cable tension stable against temperature variations. The viaduct is exposed to wide thermal variations throughout the day and year. ARCA’s compensation devices absorb these expansions and contractions of the cables, always maintaining constant tension.

Section insulators

The section insulators divide the catenary into electrical sections, facilitating maintenance and providing greater safety. This means that, in the event of an incident or the need for maintenance on one part of the bridge, it is not necessary to interrupt the entire line. In a critical infrastructure such as the Biobío, this element ensures operational flexibility and maximum safety for technical staff.

 

An international alliance of trust

Behind a work of this magnitude there is not a single company, but the sum of wills, knowledge, and experience of some of the most prominent actors in the railway sector. The new Biobío bridge is the best example of how international collaboration transforms a historic challenge into a shared achievement.

• EFE Trains led the vision and institutional drive to modernise mobility in Chile.
• SACYR contributed its construction capacity to raise a colossal infrastructure: 1.8 km of bridge and 325 m of Chepe Tunnel.
• ICIL ICAFL executed with precision the installation of the tracks and the catenary, integrating the railway heart of the project.

ARCA, with its critical electrification components, ensured that the infrastructure was not only imposing, but also safe, reliable, and ready for the future.

The greatness of the Biobío is not only structural, but also human.

 

Conclusion

The new Biobío railway bridge is not only the largest infrastructure of its kind in Chile: it is a symbol of progress. It represents how engineering can transform territories, improve the quality of life of thousands of people, and pave the way for more sustainable mobility.

In this project, every actor played a fundamental role. And ARCA, with the supply of its critical electrification components, contributed to ensuring that the largest railway bridge in Chile is also a benchmark in safety, reliability, and modernity.

The Biobío demonstrates that, when vision, international collaboration, and technological innovation are combined, railway projects transcend infrastructure to become drivers of social and economic development.

At ARCA, we design and supply railway electrification components that combine innovation, safety, and reliability.

Let’s talk about how we can add value to your infrastructures.