Lenses

Standard Railroad Signal Colors

Red – Stop
A red signal indicates absolute stop. The track ahead is occupied, blocked, or otherwise unsafe to enter. The train must come to a complete stop before passing the signal.

Amber (Yellow) – Caution
An amber or yellow signal warns the engineer to reduce speed and proceed with caution. It generally indicates that the next signal may require the train to stop or that conditions ahead require a slower speed.

Green (Teal) – Clear/Proceed
A green signal indicates that the track ahead is clear and the train may proceed at the maximum authorized speed for that section of track.

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Special & Auxiliary Signal Colors

Lunar White – Restricted Movement
Lunar white is a soft bluish-white signal used to authorize restricted movements, such as backing movements, switching operations, or entering yards and sidings where standard mainline signals do not apply.

Blue – Worker Protection (Rule #26)
Blue signals are used to protect railroad employees who are inspecting, servicing, loading, or repairing equipment. Under railroad operating rules, equipment displaying a blue flag or blue light must not be moved until the blue protection has been removed by the person or crew who placed it.

Purple – Restricted Route (Historical)
Purple lenses were historically used on certain dwarf signals, switch indicators, and siding movements to identify restricted routes or special track conditions. While uncommon today, they remain of interest to railroad historians and collectors.