SuperTile by Num
Tilable road layout with underground freeway grid. Gravel roads are for parks (delete them after placing parks!). Costs $170,000 to build. REQUIRES A VERY FLAT MAP!
More pictures here: http://imgur.com/a/1TY4C
Reddit: http://www.reddit.com/r/CitiesSkylines/comments/374c9t/high_density_low_traffic_no_public_transport/