What is the purpose of a solid white line between lanes of traffic moving in the same direction?

The purpose of a solid white line between lanes of traffic moving in the same direction is primarily to discourage lane-changing, especially in high-risk locations. A solid white line signals to drivers that changing lanes in this area may not be safe or advisable. These lines are often found in areas where there is an increased likelihood of accidents, such as near intersections, merging areas, or locations with significant pedestrian traffic.

While a solid white line also serves to visually separate lanes of traffic, its main intent is to indicate that drivers should remain in their lane to enhance safety. The solid nature of the line suggests that crossing it could lead to potentially dangerous situations, hence reinforcing the idea that maintaining one's lane is the safer option in those specific zones. This function is essential for managing traffic flow and reducing the risk of collisions.