What is the horn signal used to indicate a fire or smoke condition exists?

The horn signal indicated by "O - O" is used to notify that a fire or smoke condition exists. In the context of LIRR operations, these horn signals play a crucial role in communicating urgent information regarding safety hazards. The "O - O" pattern is specifically designated to clearly convey the presence of a fire or smoke, ensuring that crew members and others in the vicinity are alerted to take immediate action.

This signal is distinct and different from other patterns, which serve different purposes, such as alerting for an emergency stop or other operational communications. Understanding and recognizing specific horn signals, like "O - O," is essential for maintaining safety protocol and effective communication in emergency situations on the railroads.