Parallel curved lines with different colours

Apologies if this question has been asked. Im new to the forum (first question actually) and I still dont know how to navigate/search properly.


3 identical CURVED lines. Left, Center, Right  

Left (Solid Pink) and Right (Solid Yellow)) are basically highlight colours of Center  (Dashed Black)  (image attached)

The center line is copied and pasted 2x and the colour changed and manually moved.
However for this doesnt work for the third type of line. 
is there a better way to do this?

Thanks in advance!