How to model a subgrade with varying slope

Hi,

I am creating a template in InRoads SS2.  My question is how to create a template of a road whose subgrade has  a varying slope when the road is superelevated.

The finish road is 2.5%.  The subgrade is 4% initially.  When road superelevates  to +/-7% the subgrade maximum slope becomes +/-7% also.

I have a created one already but involved i think with a lot of workarounds so i am curious to know how experienced designers/modelers/engineers do this.

Thanks,

Ron