What should a train with an operable ACS do at an Absolute Clear signal?

A train with an operable ACS (Automatic Control System) should recognize that an Absolute Clear signal indicates the track ahead is clear and allows for safe movement. However, the presence of an operable ACS can necessitate additional procedural steps to ensure safety and compliance with operating rules.

The correct choice is to stop and contact the block operator. This ensures that the train's operation aligns with safety protocols and allows the block operator to confirm that all systems are functioning correctly and that it is indeed safe to proceed. This check is crucial, especially if there are any uncertainties about the train's following conditions, such as the status of signals further down the line.

Other choices imply that the train may proceed without verifying crucial details with the block operator, which could lead to unsafe conditions if there are any underlying issues, such as signal malfunctions or changes in track status that the ACS may not automatically detect. Thus, stopping to contact the block operator is a vital step in maintaining operational safety.