What action is required by a Dispatcher after stopping all trains at a malfunctioning crossing?

The correct action a Dispatcher must take after stopping all trains at a malfunctioning crossing is to issue a Form D Line 12 to trains approaching the crossing. This is a crucial step in ensuring safety and maintaining protocol. By issuing this form, the Dispatcher provides a clear directive regarding the restriction of movement at the crossing, ensuring that train crews are fully informed of the crossing's status and can take the necessary precautions. This action emphasizes the importance of communication and documentation in rail operations, particularly in situations where safety is at risk.

Other options may pertain to broader safety and communication protocols, but they do not fulfill the immediate requirement of formally notifying train crews about the specific situation at the crossing. This form serves as an official record and instruction, central to the Dispatcher’s duties in managing train movements and ensuring the safe operation of the railway.