Nice little grade separated roundabout design. Will have to work on one (when I learn how) with the rbt underneath. Thanks for the inspiration.

Good job on the junction though :D I will be using it.

it depends on the landscape as well... some Junctions are either up or down roundabouts... on the A3(m) one junction has the roundabout under it and the next one its over.

I think roundabouts under major roads are more common in urban areas, and roundabouts over major roads are more common for motorways. Have just subscribed to this item. Hopefully it will be ideal for a highway interchange in my British map.

I would say that the author is more in line with motorway style/main A route where as the link from Erynn is more ring road/city centre

I'm more used to this type https://www.google.co.uk/maps/@51.486437,0.01735,3a,75y,48.7h,88.68t/data=!3m4!1e1!3m2!1ss40aXTJoLmLxy8EgbCqhIQ!2e0

Really? I was thinking of something like this (M1 junction at Loughborough) as a pretty typical example of what I was aiming for: https://www.google.co.uk/maps/@52.7596818,-1.2688125,16z

british roundabount intersections usually have the road go over the roundabout, not under. It's generally easier to build.