What must a train do if it slows to below 10 MPH while in a block indicated for proceed?

When a train slows to below 10 MPH while in a block indicated for proceed, it must proceed at restricted speed. This requirement is in place to ensure safety, particularly in situations where a train may encounter unforeseen circumstances or obstacles.

Restricted speed is defined as a speed that allows the train to stop within half of the visible distance ahead, and it provides the crew the ability to respond to any issues that may arise while traveling. This ensures that even at slower speeds, the train can navigate safely, maintaining control and allowing for proper braking distances.

The other options suggest actions that either do not align with the safety protocols associated with proceeding in a signal block or suggest unnecessary actions that could hinder the train’s operations without contributing to overall safety. Proceeding at restricted speed is the best practice in the scenario presented.