18 15 Why not stop early?

I don't know much about the specific things, but as far as I know about railways, I can tell you that what you said has nothing to do with the signal. In bad environmental conditions, visibility is low, and drivers are driving at a prescribed low speed. Under that condition, the driver can only operate according to the signal instructions on the locomotive and the operation monitoring device (first, within the prescribed low speed range). This regulation of the railway is to ensure that in the event of a snowstorm, for example, when the track is frozen and there are foreign objects on the track, it depends on the driver's naked eye judgment (low visibility) and can stop in an emergency when encountering obstacles. As you said, it's snowing, and the white tracks around it are buried by snow. Just stop the train yourself. Ordinary people just let you see, I guess you can't see it. If the driver drives illegally and does not drive within the prescribed low speed range,