What does a double solid white line signify?

A double solid white line signifies that it separates two lanes of traffic moving in the same direction, and crossing it is not permitted. This marking is used to indicate that drivers should not change lanes in this area. It is essential for maintaining safe traffic flow, as it helps to ensure that vehicles remain within their designated lanes, particularly in situations where lane changes could pose a risk to other drivers or lead to congestion.

In contrast, a single solid white line would indicate that lane changes are discouraged but not prohibited, while a double solid yellow line is used to separate lanes of traffic moving in opposite directions, indicating that passing is not allowed in either direction. Understanding these markings is crucial for safe driving practices and adhering to traffic regulations.