When is the engine bell required to be rung?

The requirement to ring the engine bell when approaching public crossings at grade is grounded in safety protocols designed to alert pedestrians and vehicles of an oncoming train. This practice is crucial, as it serves to provide warnings to individuals who may not see or hear the train until it is too late. By ringing the bell, train crews ensure that they are taking proactive measures to prevent accidents at locations where train tracks intersect with roadways.

The emphasis on safety at grade crossings recognizes that these points are often high-risk areas. The bell acts as an additional auditory signal in conjunction with any visual warnings, like flashing lights or crossing gates, further enhancing the visibility of the train's approach. This requirement reflects best practices in railway operations aimed at maximizing safety for both the train crew and the public.

In this context, the other scenarios do not align with the specific regulations regarding when the bell must be rung. They pertain to different operational circumstances that have separate safety protocols. For instance, while passing signals at night may require other forms of notification or adherence to different rules, ringing the bell is specifically mandated when trains approach grade crossings to ensure awareness and safety.