Final answer:
A dashed white line on multi-lane highways separates traffic going in the same direction and indicates that drivers are permitted to change lanes when safe.
Step-by-step explanation:
On multi-lane highways, a dashed white line indicates that it separates traffic going in the same direction. This type of road marking allows for vehicles to change lanes when it is safe to do so. Unlike a solid white line, which suggests that lane changes should be avoided, a dashed white line provides flexibility for drivers to move between lanes, for example, to overtake slower-moving traffic or to prepare for a turn. However, drivers must always ensure that it is safe to change lanes and must obey the posted speed limits, as well as be aware of other road conditions and traffic signals that might affect their ability to maneuver.