Pass of Brander stone signals

The Pass of Brander stone signals, also known as Anderson's Piano, are a series of railway signals that are automatically triggered by rockfalls. They are located in the Pass of Brander, between Loch Awe and Taynuilt stations on the Oban branch of the West Highland Line in Scotland.

Source: Wikipedia — Pass of Brander stone signals (CC BY-SA 4.0)