What does a solid white line indicate?

A solid white line indicates the outside edge of the traffic lane. This line serves as a boundary, highlighting where lanes begin and helping drivers understand the limits of the roadway. It is crucial for maintaining lane discipline as it provides guidance on where vehicles may travel within their designated lane.

When you see a solid white line, it typically signifies that crossing into another lane is discouraged. Unlike a broken white line, which indicates that lane changes are permitted, the solid line serves as a clear marker that maintaining one's position within the lane is essential for safety.

In this context, while it's important to recognize the roles of other options, the solid white line distinctly identifies the edge of the traffic lane, which is essential for safe navigation on roadways.