Las Raíces Tunnel

Las Raíces Tunnel: a journey back in time

Key facts: Las Raíces Tunnel

Information checked in October 2026. Opening hours, access and prices may change: confirm them before you travel.

Las Raíces Tunnel was a railway tunnel and is now a road tunnel in the Araucanía Region of Chile. Built in 1939, it connects the municipalities of Curacautín and Lonquimay, in the upper Biobío River area, at 1,010 m above sea level. At 4,528 m long, it ranks 162nd among the longest tunnels in the world. It was the longest railway tunnel in the Americas (trains no longer run through it), and it is the third-longest road tunnel in Latin America, after the "Túnel de Occidente" (or "Túnel Fernando Gómez Martínez") and the "Túnel Buena Vista Misael Pastrana Borrero", both in Colombia.

Feasibility studies began in 1911, but the final plans were not completed until 1929. Construction took ten years, from 1930 to 1940, with an investment of more than 32 million pesos at the time. The tunnel is 4.2 m wide and 5.6 m high. The main idea behind such a large investment was a transoceanic railway that would link the ports of Talcahuano, in Chile, and Bahía Blanca, in Argentina. That project was never completed. In the end, the tunnel was used by the Chilean branch railway that linked the small town of Púa, on the main north-south line (the most important one, which ran almost 3,200 km from Iquique to Puerto Montt), with the town of Lonquimay, in the Andean foothills of the Araucanía Region. When that branch line closed, the tunnel became an important route for vehicles and also a tourist attraction.

In his book "Rieles Fronterizos, ramal Púa Lonquimay" (2011), historian Héctor Alarcón Carrasco devotes a chapter to the Las Raíces Tunnel tragedy, in which 42 workers were trapped inside the tunnel for more than ninety hours after an avalanche blocked the entrance.

Today, Lonquimay is reached on the international route that connects it with Curacautín, from where you can continue toward Victoria or Lautaro (both lead to the Pan-American Highway, Route 5 South). That international route goes through Las Raíces Tunnel; the alternative road is a slow gravel road, mostly used by trucks too large to fit through the tunnel. In the late 1980s and early 1990s, the tunnel still had rails for the freight and (tourist) passenger trains that ran on the branch line, plus wooden planks along the rails for cars and horse carts. Later, when the train was withdrawn from the area, the planks were removed (most were rotten, since the tunnel leaked a lot because of the mountain's humidity and small cracks in the concrete), the tracks were covered with earth and the tunnel was left for vehicles only. The renovation was completed in 2005, leaving the tunnel as it is today: fully paved, lit inside and with traffic lights at the entrance.