Red & green Icon (traffic ) using Conditional formatting

Hi Anonymous   
Since you did not attach sample data for the index you calculated, I prepared a simple data set like in the picture and will demonstrate a  solution with a simple sum formula.
The table :

parameters fo slicer:

The measure (instead of yours):

factor_ = sum('Table'[Factor])

The measure for the conditional formatting of circles :

flag_traffic = IF([factor_]>=Selections[Selections Value],"g","r")
The modifying of conditional formatting :

 

The result :

pbix is attached

If this post helps, then please consider Accepting it as the solution to help the other members find it more quickly