When trains consist of more than one unit, how many units should be illuminated as the identifying number?

In train operations, especially when dealing with multiple units, it is essential to have a clear and consistent method for identifying the train. Illuminating only the number of one unit streamlines communication and minimizes confusion among crew members, dispatchers, and other personnel. Typically, this unit is chosen based on operational protocols, with preference often given to the leading unit.

Using only one unit's identifying number enhances clarity because it ensures that all parties are referencing the same entity, reducing the possibility of errors that could arise from multiple illuminated numbers. It aligns with the principle of maintaining simplicity in operational communication, which is crucial in a complex environment such as railroads.

While illuminating all units could potentially offer clear visibility of the entire consist, it can also lead to overwhelming information or miscommunication. Similarly, illuminating only the last unit or limiting illumination to more than one unit does not conform to the standard practice of ensuring easy identification and operational efficiency. Thus, illuminating just the number of one unit strikes the right balance between clarity and practicality.