First Patent on traffic signal fault monitoring - Feb 1965

Based on my search on internet,  related to traffic signal failures and fault monitoring, I found the earliest patents was filed in Feb 1965. This was granted in Aug 1967. Patent number is 3336574.

First sheet of the patent is here

You can see and read the complete details on internet by clicking on next line (that is title of the patent).

Title : Auxiliary controllers for warning of malfunction for electrical traffic light systems