A Signal may be considered to be
defective in the following circumstances.
Ø When it is not assuming the
required aspect even after proper operation.
Ø If there is a damage of signal roundels.
Ø Drooping or improper position of the arm.
Ø Colour light signal showing no aspect due to power failure.
Ø Flickering/Bobbing
Ø Auxiliary equipment like track circuit, Axle counter, LC gate etc.
failure.
Ø Point failure/interlocking failure.
Ø In Two Aspect territory if the Home signal fails the Outer will also be
treated as failed.
Ø In MAS if the Home signal failed the Distant shall be treated as
defective.
Ø If conflicting signals are possible.
Ø Signal blank, a white light is shown instead of a color light.
