What does a solid double yellow center line indicate on a two-way roadway?

A solid double yellow center line on a two-way roadway indicates that passing is not allowed for vehicles traveling in either direction. This marking is used to enhance safety by preventing drivers from overtaking vehicles in situations where visibility may be limited or where it is unsafe to do so. It serves as a clear visual warning that crossing the line is prohibited, which helps reduce the likelihood of head-on collisions and other dangerous situations.

In contrast, a dashed line would permit passing, while options related to U-turns or emergency vehicles do not pertain to the significance of a solid double yellow line. The main focus of this line is to maintain safe driving practices by discouraging overtaking in areas where it may pose a risk.