You can do it with the traffic light gauge as well, I just think it is simple with image.
To make your traffic light work, make the next changes in your gauge settings:
- add one more segment (it will be red by default)
- uncheck "autowidth segments" on the left bottom corner
- set lower bound for the green segment 0 (in fact, anything less than 1)
- set lower bound for the red segment 1.5 (anyhting >1 and <2)