Basically, autoroad with tunnel like bricks that are 8xCubes (Dead ends, T, X and L pieces)
Here's what i suggest you use:
Tunnel Bricks (8xCubes that are hollow)

Auto Road Bricks - Broken (does not rotate bricks)
http://www.mediafire.com/download.php?mpee8f92h1m1z28Missing IDtoRot Function: (i wrote it my self, it works on autoroad partially)
function idtorot(%ad) {if(%ad==0)return "1 0 0 0"; else if(%ad==1) return"0 0 1 90"; else if(%ad==2) return "0 0 1 180"; else if(%ad==3) return "0 0 -1 90"; else return "1 0 0 0";}
I'm just having trouble making the tunnels work with autoroad...
I don't actually need this anymore..