What is the primary function of edge lines on roadways?

The primary function of edge lines on roadways is to delineate the edge of traveled ways. This means that they serve as visual guidance for drivers to understand where the pavement ends and the adjacent area, which could be a shoulder, ditch, or another type of area not meant for vehicular travel. By clearly marking this boundary, edge lines help to prevent vehicles from inadvertently leaving the traveled way, especially in situations with limited visibility or during night-time driving.

Edge lines are typically solid white and are crucial for maintaining driver awareness of the roadway's limits, particularly in adverse weather conditions or during nighttime. This delineation contributes significantly to the overall safety and proper navigation of roads, distinguishing them from lane markings, which are designed to separate different lines of traffic.