Final answer:
A dashed white line on a multi-lane road allows vehicles to change lanes. Drivers must still ensure safety by checking for traffic and signaling before changing lanes.
Step-by-step explanation:
On a multi-lane road, a dashed white line indicates that vehicles are permitted to change lanes. This is a common road marking that provides guidance about the movement between lanes. These lines are different from solid white lines, which suggest that lane changes are either prohibited or discouraged. The dashed white line means you can cross it to pass or change lanes if it is safe to do so.
It's important for safety on the road that drivers understand such road markings. When you see a dashed white line, you must still ensure it is safe to move across, by checking for any oncoming traffic in the lane you wish to enter and using your indicators to signal your intention to other drivers.