What does a double yellow line on the road signify?

A double yellow line on the road signifies that no passing is allowed in either direction. This marking is used to indicate that the road is either narrow, or visibility is limited in such a way that attempting to pass could be dangerous. The presence of double yellow lines emphasizes the need to stay in your lane and avoid overtaking vehicles, promoting safer driving conditions for all road users.

In contrast, a single yellow line typically allows for passing if it is safe to do so, and no specific markings relate to only trucks being allowed to pass. Additionally, left turns are not exclusively designated by double yellow lines; rather, they denote the no-passing zone for all vehicles. This helps reinforce the importance of adhering to road markings for driver safety.