If the driver of a vehicle approaches a railroad grade crossing under any of the circumstances stated in paragraph (2) of this subsection, the driver: Shall stop within 50 feet but not less than 15 feet from the nearest rail in the crossing; and May not proceed until he can do so safely. The requirements of this subsection apply if: A clearly visible electric or mechanical signal device warns of the immediate approach or passage of a railroad train; A crossing gate is lowered; A flagman signals the approach or passage of a railroad train; A railroad train approaching within 1,500 feet of the crossing gives a signal audible to traffic approaching the crossing and the railroad train, because of its speed or nearness to the crossing, is an immediate danger; or A railroad train is plainly visible and is in or is approaching dangerously near to the crossing. A person may not drive any vehicle through, around, or under any crossing gate or barrier at a railroad grade crossing while the gate or barrier is closed or is being opened or closed.