I can scale the bandwidth proportionally to the traffic volumes; however, I cannot show the directionality of the movements. Volumes for directional moves are stored in two different columns of a database. My workaround for this is to import the layer twice and use two different symbologies, one for each direction. Is it to possible to do this without having to import the same layer twice?
Note that I need to show the bandwidth starting from the link so I cannot use the same offset because it create blank space between the opposite directions (it seems to me that the offset start from the middle of the thckness).
Edit: in the uploaded images you can see that the offset depends on the width of the links, so I is not possible to find a single offset value matching for all the links