What does a double solid white line indicate?

A double solid white line is used to indicate that the lanes on either side are going in the same direction but prohibit changing lanes or crossing over the line. This marking serves to ensure safety and maintain traffic flow by preventing drivers from switching lanes in areas where it may be hazardous to do so, such as near intersections or in high-traffic zones. It's important to understand this traffic symbol, as disobeying it can lead to accidents and traffic violations. The other options describe situations that are not applicable to a double solid white line, such as allowing traffic in both directions or permitting lane changes, which is clearly contrary to the intention of this markings.