DC = Dual Carraigeway.
A flyer? Sure I know it like the back of my hand.
Its not correct to say that the embankment was to meet the roads in the area. You can see the orignal road to your left coming down the embankment into Ballymun, the embankment was created to allow the bridges to pass over the M50, you go down both sides north and south, admiddedly there was a hill there before where the junction is now.
I am not aginst a tunnell all the way at all, in fact that's what it should be.
If it were stilts it could be this:
which is from the Amsterdam Metro's above ground bit.