What action is required before proceeding after a train has been uncoupled and recoupled in 4 hours or less?

The requirement to restore brake pipe pressure as indicated by a rear gauge after a train has been uncoupled and recoupled within 4 hours is essential for ensuring the safety and functionality of the train's braking system. When a train is uncoupled, the air brake system is disrupted, and the brake pipe pressure can drop. Before proceeding, it is crucial to verify that the brake pipe pressure has been adequately restored to ensure that the brakes are functioning correctly throughout the entire train.

This action confirms that all cars in the train are receiving the proper amount of air pressure needed for their respective brakes to operate effectively. By checking the rear gauge, personnel can ascertain that the brake system is fully operational and ready for safe transit, minimizing the risk of brake failures during operation.

This procedure reflects standard operating protocols aimed at maintaining safety and reliability in train operations, which underscores the importance of proper brake system monitoring. Other options, while potentially relevant to train safety, do not specifically address the immediate need to ensure that brake pipe pressure is restored after uncoupling and recoupling in a timely manner.