Which of the following is considered normal authority to pass a Block Limit Signal?

Passing a Block Limit Signal requires proper authorization to ensure the safety and efficiency of train operations. A train order serves as a formal means of communication that grants a train specific instructions, including the authority to pass signals under certain conditions, thus making it the normal authority for this action.

Train orders are issued by dispatchers to convey critical information to train crews. They are legally binding and provide clear instructions regarding limitations and specific actions required in certain situations. This formal documentation ensures that all operational protocols are followed and enhances the safety of train movements in potentially hazardous areas.

In contrast, the other options do not represent standard or accepted forms of authority for passing Block Limit Signals. A Waiver Form typically pertains to exceptions in rules but is not a recognized method of granting signal authority. A Clearance Card generally confirms that a train is cleared to occupy a block but does not serve as authority to pass signals. Lastly, while verbal confirmation can facilitate communication, it lacks the formal documentation necessary for operational integrity and safety, making it unreliable for authorizing the passing of signals.