This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Streckenblock S. de March Streckenblocksignal Neubau der Signale nach dem polnischen Signalsigmenten von Swisstack Swisstack Funkruf WP CVUWP CVU Railway signals in Poland
Page 2023 Free-images.com. All images are Public Domain