What is indicated by a blue light in the Flatbush Ave. / Atlantic Ave. tunnels?

A blue light in the Flatbush Ave. / Atlantic Ave. tunnels is specifically used to indicate the presence of fire alarm and power disconnect boxes. This designation serves a critical safety purpose, ensuring that personnel can quickly identify the location of these crucial emergency systems. When responders see a blue light, they can efficiently direct their efforts toward accessing fire alarms or disconnecting power in case of an emergency, thus helping to prevent fire hazards and manage electrical risks effectively.

Understanding the role of such signaling systems is essential for maintaining a safe working environment within the tunnels, especially given the complexities and potential hazards associated with railway operations. The other options refer to elements that, while important in their own contexts, do not accurately correspond to the specific meaning of a blue light within this particular area of the LIRR infrastructure.