A. Except in cities or towns, whenever any person driving a vehicle approaches a railroad grade crossing under any of the circumstances stated in this section, the driver of the vehicle shall stop within 50 feet but not less than 15 feet from the nearest rail of such railroad, and shall not proceed until he can do so safely. The foregoing requirements shall apply when:
1. A clearly visible electric or mechanical signal device gives warning of the immediate approach of a train;
2. A crossing gate is lowered or a flagman gives or continues to give a signal of the approach or passage of a train;
3. A train approaching such crossing gives the signals required by § 56-414;
4. An approaching train or any self-propelled machinery or automobile type vehicle traveling on a railroad track is plainly visible and is in hazardous proximity to such crossing, regardless of whether a clearly visible electric or mechanical signal device or flagman gives warning.
B. No person shall drive any vehicle through, around, or under any crossing gate or barrier at a railroad crossing while such gate or barrier is closed or is being opened or closed.