Which interlocking signals indicate permissive signals in Harrison Yard?

In the context of railroad operations, permissive signals are designed to allow trains to proceed at a reduced speed, indicating that a train may go through an area where conditions are safe but require caution. The signals identified in Harrison Yard as permissive fall within the range of 140X and 180X, which are specific designations correlating to certain operational protocols and restrictions.

The choice labeled as B includes interlocking signals that are identified explicitly in the procedure and operational guidelines for the yard. Understanding the characteristics of these signals is vital for train engineers, as they dictate operational speeds and the general conduct of trains in the vicinity of the yard.

By contrast, the other options include signal combinations that may not represent the permissive indicators explicitly defined for Harrison Yard. Each signal’s designation typically carries specific instructions and meanings, which are critical for safe and efficient train operations within the system. Signals such as 100X, 120X, 150X, 200X, 130X, and 160X either fall outside the operational definition of permissive signals for this location or indicate other signal aspects or commands that do not carry the same implications for train movement.

Recognizing the correct permissive signals is essential for ensuring that engineers can navigate the