For high traffic, a roundabout would have to be truly huge. It isn't viable unless land is practically free. You need something more like this: https://en.wiki

For high traffic, a roundabout would have to be truly huge. It isn't viable unless land is practically free. You need something more like this: https://en.wikipedia.org/wiki/High_Five_Interchange https://en.wikipedia.org/wiki/High_Five_Interchange That crosses 16 lanes with 14 lanes. (3,5,5,3 with 3,4,4,3)