urban roadway design using site modeler

Hi all:

Am using site modeler for my roadway layout that consist of 4-8 traffic lanes with intersections. It has a raised center median that varies in width and horizontal location to the PGL because of the turn lanes.

For the left turn lanes and part of the left turn lane taper the median is on the left side of the PGL and the crown needs to keep going up till it hits the curb and gutter. How do you get the crown do go beyond the PGL for these turn lanes and tapers?

Thanks!