When is it permissible to pass another vehicle on the left?

Passing another vehicle on the left is permissible when instructed by a traffic director. A traffic director has the authority to manage the flow of vehicles and pedestrians at intersections or areas where visibility or road conditions may pose hazards. Following their instructions is crucial for maintaining safety and ensuring compliance with traffic regulations.

In situations where a traffic director is present, they may direct vehicles to pass another on the left to optimize traffic flow and prevent confusion or accidents at busy intersections. This instruction is an exception to the general rule of passing on the right and is intended to enhance safety and efficiency on the road.

In the context of the other choices, while passing on a one-way street is often lawful, the critical factor is the presence of a traffic director's specific instructions, which take precedence. Similarly, passing when a driver signals to turn right or when a vehicle is stationary carries risks or may not apply universally, thus making the directive from a traffic director the most authoritative and relevant context for permissible left passing.