How long must a train's delay be communicated to the train crew by the dispatcher?

The correct answer is based on the regulations governing train operations, which stipulate that a train dispatcher must communicate any delay exceeding a specified threshold to the train crew. In this case, a delay of 20 minutes or more is the standard that requires notification. The rationale behind this specific timeframe is to ensure that the crew is adequately informed of operational changes that could impact their schedules, allowing them to adjust their plans accordingly and maintain safety and efficiency on the railway.

A delay less than 20 minutes might not necessitate formal communication because it may not significantly affect operations or crew management. However, once the delay reaches this 20-minute mark, it becomes essential for the dispatcher to inform the crew to keep them updated and ensure they can effectively manage their responsibilities during the operation. This practice is designed to enhance safety and operational effectiveness within the railway system.