What must an operator provide to restrict access to a site before leaving?

An operator must provide effective measures to restrict access to a site to ensure safety and security after leaving. The use of barricades or fences is crucial because they create a physical barrier that prevents unauthorized entry, helping to protect both individuals and the site itself from potential hazards or accidents. Barricades can be quick to set up and often indicate that the area is off-limits, while fences provide a more permanent solution.

Barricades or fences contribute significantly to controlling access to the work area, indicating that the site may have ongoing work or hazards, thus reducing the risk of injury to unsuspecting individuals. This practice is essential for compliance with workplace safety standards and demonstrates the operator's commitment to maintaining a secure and safe environment after they have vacated the site.

The effectiveness of barricades and fences in restricting access makes them the most suitable choice among the options provided.