In which situation is passing on the right usually permitted?

Passing on the right is usually permitted in situations where there are multiple lanes of traffic moving in the same direction, such as on highways. This practice is based on the concept that vehicles traveling at different speeds can utilize the available lanes more efficiently. In these scenarios, the left lane is often reserved for overtaking slower vehicles, while the right lane can be used for passing or driving at a slower speed, depending on the circumstances.

In contrast, passing on the right when another vehicle is parked may not be safe or allowed because the parked vehicle's driver may not be aware that a vehicle is approaching from behind. Similarly, when a vehicle is signaling to make a left turn, passing on the right can create confusion and increase the risk of an accident. Therefore, on highways with multiple lanes, it's not only permitted but is also a common practice to enhance traffic flow and safety.