The Engaña Tunnel: A 1941 railway project that never received rails

The Engaña Tunnel is a never-completed railway tunnel in Spain, connecting the provinces of Burgos and Cantabria through the Cantabrian Mountains. It was part of the proposed Santander–Mediterranean railway line, an attempt to connect the Bay of Biscay with the Mediterranean Sea. Construction lasted for over seventeen years, from 1941 to 1959, employing hundreds of workers, including Republican prisoners during the first years. At the time, it was the longest railway tunnel in Spain, with a length of 6,976 metres, but the rails were never laid.

In 1941, the Francoist government awarded the contract to Ferrocarriles y Construcciones ABC. The company employed penal labor from labor camps, with 560 prisoners by 1943. Construction resumed in 1951 with Portolés y Cía, with teams from both entrances meeting on 26 April 1959. The tunnel was officially inaugurated on 9 May 1959, but the construction had not yet been completed. By 1961, the railway line was indefinitely halted due to restrictions on public investment following the Plan Nacional de Estabilización Económica and unfavorable reports from the World Bank.

The quality of the material used decreased as the construction rate increased from half a meter per day in the early 1950s to three meters per day in the final years. This lack of proper steel reinforcement led to widespread deterioration and the collapse of some sections in 1999 and 2005. While residents and truck drivers used the tunnel as an alternate road for years, it is now impassable for vehicles due to ceiling debris. Today, some sections remain flooded, and travel on foot is extremely dangerous due to piles of debris and the risk of landslides.

Sources: Wikipedia, OpenStreetMap, Wikidata, Wikimedia Commons