Fahrt frei!

The German mechanical semaphore signal, in use since the 19th century, still reliably indicates a clear route for trains by the position of its arms.

The German mechanical semaphore signal, in use since the 19th century, still reliably indicates a clear route for trains by the position of its arms.

The German mechanical semaphore signal, in use since the 19th century, still reliably indicates a clear route for trains by the position of its arms.

The German mechanical semaphore signal, in use since the 19th century, still reliably indicates a clear route for trains by the position of its arms.