According to Rule 629, under what condition can a train pass a Stop signal?

In the context of train operations, Rule 629 provides specific guidelines on when a train may pass a Stop signal. The correct answer is that a train can only pass a Stop signal with Form L authorization. This rule is designed to ensure safety and coordination among the railway personnel. Form L is a formal method that provides the necessary approval for a train to proceed past a Stop signal under controlled and specified conditions.

This authorization incorporates various safety checks and reassurances that the movement of the train is warranted and that the crew has been adequately briefed on the circumstances surrounding their action. This process is critical in preventing accidents and ensures that all parties involved are aware of and agree upon the actions being taken.

While alternatives might suggest different scenarios under which a train could pass a Stop signal, they do not align with the defined protocols laid out in Rule 629. For instance, permission from the engineer or verbal Rule 241 authorization may not encompass the comprehensive safety measures outlined in Form L. Furthermore, a clear signal indication would imply that the signal is not a Stop signal at all, thus eliminating the need for any authorization to pass it.