What authority does a work extra train need to operate in single track territory under rule 251?

A work extra train operating in single track territory under rule 251 must adhere to specific protocols for safety and operational efficiency. In such cases, proper signal indication or permission from the block operator is essential. This ensures that the work extra train is authorized to proceed safely on that segment of the track, as it may be sharing the single track with other trains. Proper signal indication serves as a visual confirmation that the track is clear and safe for use, while permission from the block operator provides an additional, authoritative confirmation. This dual approach helps to prevent accidents that could arise from unauthorized movements in single track environments. The requirement for proper authorization is critical in maintaining safety standards and ensuring the efficient functioning of train services in shared track scenarios.