I have a question about signal aspects coming out of a siding in the Georgia/Alabama area, specifically where there are two signal heads, one of them with only one light, which I've never seen to be anything other than red; the other signal a traditional three color Green/Yellow/Red.
From the siding back to main track it looks like there will always be red/green, red/yellow or red/red. Does that "single light" signal head ever display anything different from red in the southern territory? Am I correct to assume the only indications would be diverging clear and diverging approach, or can you get, for example, an advance approach yellow/yellow or diverging approach restricted with a flashing yellow on the lower signal head?
For the main track with tricolor over single head - can you get indications such as advance approach or approach restricting or approach diverging on that signal?
Thanks in advance if someone can help with this!