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.
Keywords from Image Description:
NS lichtseinstelsel gedoofd groen. en Railway signal two heads low signal of the railway signalling system of the Dutch railways Green lower light upper light dark proceed at low speed nl Laag geplaatst sein met twee lichten van het lichtseinstelsel van de Nederlandse Spoorwegen Groen licht bovenste licht gedoofd lage snelheid