Which of the following is NOT considered a fixed signal?

A yellow lantern hung on a column is not considered a fixed signal because it typically does not have a permanent installation. Fixed signals are designed to provide consistent, ongoing instructions to train operators regarding the status of the track ahead, and they are permanently mounted in specific locations.

In contrast, a yellow lantern can be temporary or used in specific situations, such as work zones or areas of maintenance, and may not be a reliable source of ongoing information. Fixed signals, such as stop light signals, fixed bridge indicators, and track switch signals, are installed at specific locations and provide clear, unambiguous information crucial for safe train operations. These signals are integral to train management systems, ensuring trains can operate safely and efficiently by providing clarity about block occupancy, speed restrictions, and track configurations.