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. A screen of wires, linked to semaphore signals, is erected on the mountainside alongside the railway track. In the event of one or more wires being broken, signals in each direction are automatically placed at 'danger'. They are part of a warning system that advises train drivers to exercise caution in the event of a rock-fall, and cover a section of track that is just over 4 miles (6.4 km) in length.