Latin America’s Longest Suspension Bridge Is in Chile’s Most Earthquake Prone Area

In the coming years, the Chacao Channel in Chile – about 48 km from the capital of the Los Lagos region, Puerto Montt – will be crossed by the longest suspension bridge in Latin America.

A strategic and revolutionary infrastructure because, thanks to its total length of 2,754 meters and its main spans of 1,155 and 1,055 meters, it will connect the island of Chiloé to the mainland, reducing crossing times from the current 30 – 45 minutes by ferry to just three minutes by car.

A project that has distant origins, first conceived in the 1960s, revisited in the 2000s, then abandoned, and finally relaunched in 2012.

Construction began in 2018, with predictions pointing to the opening of the structure in 2028. The necessary time to complete what is considered a cutting-edge engineering achievement, a highly safe, earthquake-resistant suspension bridge capable of withstanding intense marine currents and constant winds exceeding 200 km/h.

The numbers of the Chacao Bridge reveal much about its engineering excellence. The earthquake-resistant architecture consists of a steel deck 23.8 meters wide and three reinforced concrete towers: two lateral towers (one to the north standing 199 meters tall and one to the south at 157 meters) and a central tower approximately 175 meters high, positioned on Roca Remolinos, an underwater rocky bank located right in the middle of the channel.

The stability of the towers is ensured by foundations extending up to 58 meters below sea level, while structural continuity is provided by the suspended spans, which host two roadways with two lanes each.

But perhaps the most significant feature is the bridge’s seismic resistance. The structure is located just 80 km from the fault responsible for the 1960 Valdivia earthquake, the biggest earthquake ever recorded in history, and not far from the Ancud fault, which in 2010 produced another devastating quake.

This seismic hyperactivity imposed exceptional design standards, starting with the characteristics of the towers. The central tower adopts an “A” shape, specifically designed to guarantee high ductility and energy dissipation during strong tremors.

The steel deck is also constructed to ensure maximum flexibility, while the lateral towers reduce aerodynamic drag and improve seismic and dynamic resistance.

After all, the ability to withstand even major earthquakes has been a feature of these great suspension bridges for years. Like those built by the Webuild Group over the Bosphorus, or the  Akashi Bridge in Japan, which withstood the 1995 Kobe earthquake with a magnitude of 7.3.

These are examples of how scientific innovations in the construction sector have made these infrastructures capable of withstanding devastating earthquakes as well as violent winds reaching nearly 300 km/h—earthquake-resistant structures that have conquered nature’s challenges while providing valuable services to communities and local economies.

The major focus on engineering innovations for the future Chacao Bridge responds to the goal of creating a structure capable of profoundly transforming transport in a highly populated region.

Once operational, the new infrastructure will allow uninterrupted connection along Chile’s main highway – Route 5 – from Arica, a port city in the north of the country, to the city of Quellón, also with a port, located in the south of Chiloé Province. In short, a new boost for mobility in southern Chile.

Today, the island of Chiloé, the second largest in the country after Tierra del Fuego, is connected to the mainland exclusively via a system of ferries operating along the Chacao Channel.

These connections, while enabling the transit of approximately 1.5 million vehicles per year and freight transport, are subject to marine weather conditions with frequent interruptions in the case of strong winds, currents, or fog.

The commissioning of the Chacao Bridge will have a direct impact on the island’s economic and logistical competitiveness, reducing travel times, increasing tourist appeal, and promoting market integration.

According to estimates by the Chilean government, vehicle traffic could double in the first year of operation compared to current levels, reaching approximately 3 million vehicles per year. In the long term, the Chacao Bridge will not only be an engineering marvel in an extreme seismic zone but also a powerful catalyst for development in southern Chile, helping to reduce infrastructure disparities and fully integrate Chiloé Island into the country’s production and transport system.