What should be done before changing lanes to ensure safety?

Before changing lanes, it is essential to check over your shoulder to ensure safety. This action allows you to visually confirm that there are no vehicles or obstacles in your blind spot that may not be visible in your mirrors. Side mirrors provide a good view of adjacent lanes, but they do not cover areas directly beside the vehicle where objects may be hidden from view. By turning your head and looking over your shoulder, you gain a clearer perspective of the entire lane and surrounding environment, reducing the risk of a collision during the lane change.

Checking your fuel level is important for overall vehicle maintenance but does not contribute directly to lane-change safety. Relying solely on side mirrors may leave blind spots unchecked, leading to potential hazards. Using the horn can alert other drivers but is not a substitute for ensuring that the lane is clear before making the maneuver. Thus, checking over your shoulder is the critical step to maintain safety when changing lanes.