Just west of Tua, the railway crosses the Rio Tua, a tributary of the Rio Douro, on a steel viaduct. A short distance up the Rio Tua is the Barragem de Foz Tua, the large dam visible in this photo. Just to the right of the dam is a tunnel mouth, this is the course of the "Linha do Tua": opened in 1887 to Mirandela and Bragança, most of it closed in stages between 1998 and 2008. From 2008 a short section around Mirandela was operated as the Metro de Mirandela, but this was closed in 2018. The route was blocked by the dam here at Tua in 2016. I explored this area later in the day, including walking up to the road bridge that is visible.