What speed must an assisting train operate at after receiving proper signal indication or verbal permission?

The requirement for an assisting train to operate at restricted speed after receiving proper signal indication or verbal permission is based on safety protocols in train operations. Restricted speed is defined as a speed that allows for stopping within half the distance of clear track ahead. This ensures that the train can react promptly to any unforeseen hazards, such as another train, obstacles, or work zones that may not be immediately visible.

Operating at restricted speed provides a margin of safety, particularly in situations where the assisting train may be in close proximity to potentially hazardous areas. It minimizes the risk of accidents and ensures that the crew has ample time to assess the situation ahead without exceeding a speed that could complicate matters.

In contrast, normal operational speed and maximum authorized speed may not take these safety considerations into account, as they do not necessarily limit the train to stopping distances that can respond appropriately to sudden challenges. Variable speed based on visibility, while it may consider the conditions, does not provide a consistent safety standard required in such scenarios.