What is the significance of a solid yellow line on the road?

A solid yellow line on the road primarily serves to indicate that no passing is allowed. This marking is crucial for maintaining safe driving practices, particularly on two-lane roads where visibility may be limited. When you encounter a solid yellow line, it signifies that crossing over it to overtake another vehicle could pose a danger due to oncoming traffic. This rule helps to reduce accidents by preventing drivers from making unsafe maneuvers.

The other options presented do not accurately describe the function of a solid yellow line. For example, while a center line is indeed used to designate the separation of lanes, a one-way street typically uses different types of markings. Similarly, a solid yellow line does not allow passing, nor does it indicate a bike lane, which would instead be marked in a different manner to distinguish it clearly from vehicular lanes. Understanding these markings is essential for all drivers to ensure their safety and compliance with traffic regulations.