What is the first step when passing an automatic signal displaying 'Z' or 'D'?

The first step when passing an automatic signal displaying 'Z' or 'D' is to stop short of the signal. This procedure is crucial because signals displaying these indications typically indicate a restriction or an important caution regarding the track ahead. Stopping ensures that the engineer can assess the situation safely and determine the appropriate course of action, in compliance with safety regulations and operational protocols.

By stopping short of the signal, the engineer maintains control of the situation, allowing for a proper evaluation of conditions, such as track status, potential obstructions, and any safety measures that may need to be implemented before proceeding. This approach minimizes the risk of accidents and ensures that all protocols are followed in maintaining safe operations.