What is the mandatory procedure when a commercial passenger coach approaches an unguarded railway level crossing (无人看守铁路道口)?

1. Accelerate quickly across the tracks before a train appears
2. Shift into neutral and coast across the railway tracks
3. Execute 'Stop, Look, Listen, Pass' (一停、二看、三通过): stop before the stop line, verify no approaching train from both directions, shift to low gear, and proceed steadily across without shifting gears on the tracks
4. Honk horn and drive across without looking