Under what conditions may OCS be in effect at designated locations?

The correct answer is that OCS (Occupational Control System) may be in effect in addition to yard limits. This situation recognizes the need for enhanced safety and control measures in areas where yard limits are established while also allowing the use of OCS. Yard limits are zones where specific rules apply to protect workers and equipment, and the application of OCS in these areas can further enhance operational safety, providing a structured framework for coordination during various maintenance or operational activities.

Establishing OCS alongside yard limits allows for greater flexibility and safety when multiple crews or tasks are conducted simultaneously in close proximity to active railway traffic. It underscores the importance of maintaining clear communication and control over work zones, ensuring that all personnel are informed of their roles and responsibilities while working alongside the moving trains or equipment.

In contrast, OCS cannot be properly established under the conditions of no yard limits, when trains are not operating, or only during maintenance activities, as each has specific implications for operational safety and the application of control measures.