When can a security guard control traffic on public roads?

A security guard can control traffic on public roads when instructed to do so by a police officer. This is because police officers have the authority to manage traffic and can delegate that responsibility to security personnel if necessary. This delegation typically occurs in situations where crowd control is needed or during special events where traffic management is essential to ensure public safety.

In contrast, while a security guard might have authority on private property or in specific scenarios, they do not possess the same level of authority on public roads without police approval. Additionally, controlling traffic at all times or only during emergencies does not align with the structured protocol established by law enforcement, which governs the conditions under which traffic control can be enacted by private individuals, including security personnel.