What is the purpose of a solid white line on roads?

A solid white line is primarily used to mark the edge of the roadway, serving as a guide for drivers to maintain their lane and avoid veering off the road. This line helps in delineating where the roadway ends, which is especially important in areas without curbs or barriers. It provides an important visual cue, ensuring that motorists remain safely on the roadway, particularly in low visibility conditions or during inclement weather.

While it’s important to recognize that options indicating stop lines, traffic separation, or pedestrian crossings serve their own distinct purposes, they do not define the specific role of a solid white line. Stop lines, for example, are often found at stop signs or traffic signals, indicating where vehicles must halt. Lines that separate traffic flowing in opposite directions typically are solid or dashed yellow lines, while pedestrian crossings may be marked with different types of lines or symbols.