When a bus driver obeys a stop sign and stops before a level crossing, he is also obliged:

1. To use the horn and turn off the radio.
2. Correct answer: To open the front door.
3. To open the rear door to enable passenger escape.
4. To wait until at least one train passes.

WhyWhen a bus driver stops at a Stop sign before a crossing, they also open the front door. That way they hear the train better, and if people have to get out, the exit is already open.