I used to live near the Mixing Bowl [1] (not exactly an inspiration in city planning), so I just wonder how these would hold up under congestion. The mixing bo

I used to live near the Mixing Bowl [1] (not exactly an inspiration in city planning), so I just wonder how these would hold up under congestion. The mixing bowl proves you can do anything with ramps (& no lights!), but building flat intersections seems much harder. Building freeway ramps isn't really that hard, though, so I don't see the point in restricting dimensions. It's good not to let it get out of hand like VDOT, but concrete is pretty cheap. Maybe if you've got a lot of 45mph roads connecting you'd want good lighted designs. Where I live now it's all 40s connecting to 55s connecting to the interstate, so it'd be pretty moot. Planning for road speeds & traffic rates seem far more important than keeping things flat. [1] http://en.wikipedia.org/wiki/Mixing_Bowl_(Springfield) http://en.wikipedia.org/wiki/Mixing_Bowl_(Springfield)