Aspect Signals (Styled off of BR Blue paint schemes)

Aspect signals came into use in the mid to late 20th centuary around the 1970s

General Aspect Signals work similar to Traffic lights with the standard Red yellow Green however on train signals the ordor is reversed with the red being at the bottom a green at the top this isn't the only combination however they can as seen above be simple Green Red Signals or in some cases Yellow Green Yellow Red signals