When must on-track equipment obtain dispatcher authority in relation to OCS?

On-track equipment must obtain dispatcher authority before fouling or occupying the main track in relation to On-Track Control System (OCS) procedures. This requirement is crucial for ensuring safety and preventing potential collisions with trains that may be using the main track. The dispatcher has the responsibility of controlling train movements and ensuring that the track is clear for on-track work to occur.

By obtaining this authority, workers and equipment can confirm that they have permission to be on the track and that all necessary precautions have been taken. This procedure helps maintain an organized flow of rail operations and reduces the risk of accidents.

In the context of the other options, obtaining dispatcher authority once per shift or only during emergencies does not provide adequate safety measures for instances where there is interaction with the main track. Similarly, simply needing approval when entering a yard does not encompass the broader requirement for all activities involving the main track. Therefore, requiring authorization before fouling or occupying the main track is a necessary protocol that ensures the integrity of train movements and the safety of personnel working in the area.