A single solid white line on the road divides lanes of traffic traveling in the same direction and discourages lane changes. White lines divide lanes of one-way traffic, and yellow lines divide lanes of two-way traffic.
Road markings are used to direct drivers regarding lane usage, road conditions and passing safety. Double solid white lines divide two lanes of one-way traffic and prohibit lane changes. A broken white line divides lanes of one-way traffic and permits lane changes. Double solid yellow lines indicate that traffic is traveling in both directions, and passing is not permitted on either side of the center line.