You might want to visit MD SHA's CADD Standards web page - within their data is a training data set for the Roadway Designer. They do some interesting things with TC points. Also, I had received a data set from a gentleman at Vermont's AOT where they modeled a roundabout in Roadway Designer. There is a number of very intricate design possibilities within these tools that make gore and intersection cleanup almost automatic.
People found ways to do very creative thing with the Roadway Modeler - given time, the same will occur with the Roadway Designer.
I'm not sure if I have the roundabout data set anymore, but on their web site is a document on intersection design that I believe actually explains many of the techniques used in the roundabout example.
Charles (Chuck) Rheault CADD Manager
MDOT State Highway Administration