On a four-lane divided highway, what is the purpose of lane lines?

Lane lines on a four-lane divided highway are essential for organizing and managing the flow of traffic. Their primary purpose is to separate lanes of traffic that are moving in the same direction. This separation helps to ensure that vehicles remain in their designated lanes, enhancing safety by reducing the likelihood of collisions and allowing for smooth traffic movement.

Additionally, lane lines often guide drivers in maintaining proper distance from other vehicles, provide visual cues for safe passing, and signify where the driving surface is intended for use by vehicles. On a divided highway, this clear delineation is particularly important, as it helps in preventing lane changes that could lead to dangerous situations.

In contrast, the other options focus on different functions that do not apply to lane lines on a divided highway. Emergency lanes, parking zones, and bicycle lanes are typically marked with specific symbols or markings designed to communicate distinctly different rules or uses, making them separate from the function of lane lines.