Never | |
Always | |
If the weather permits | |
If it improves your ability to see or hear an approaching train |
Safe for both cars and buses | |
Safe for all conditions | |
Safe for buses, cars can exceed this speed | |
Safe for cars but not necessarily for buses |
Can be locked partially open for fresh air | |
Can be left open as a regular practice | |
Must be kept closed and locked at all times | |
Can be locked fully open for fresh air |