When reversing a large articulated truck or public transport coach into a narrow loading bay or blind alley, what safety measure should always be taken?

1. Use a competent guide/guide-person on the ground positioned in your view to direct the maneuver, while sounding the reverse alarm and checking mirrors
2. Reverse at high speed without looking into mirrors
3. Turn off all exterior lights and sound the horn continuously
4. Rely solely on intuition without checking behind the trailer