What type of communication should be established when a stop signal is activated?

When a stop signal is activated, radio communication with dispatch is crucial. This form of communication ensures that the engineer can quickly relay the situation, receive instructions, and update the dispatch about the train's status. Proper communication helps to coordinate responses, facilitate safety measures, and maintain the overall operational flow of the rail system.

Other forms of communication, like non-verbal signals or visual signals from crew members, may be helpful but are not as effective in conveying the necessary information regarding the status of the train and the actions required in response to a stop signal. Similarly, alerts to other trains are important but secondary to establishing direct and clear communication with dispatch to ensure that safety and protocol are maintained across the board.