Hello Devin,
not sure if I fully understand your problem. I assume you've got 3D polylines running the length of your road. Edge of pavement, top and bottom of ditch and batter and so on.
You can create a corridor and template using those lines. Select one as your main alignment, and create a alignment using this existing line. This line should preferably be the longest of them.
Afterwards you create a corridor, select the just created alignment and you add all the other polylines as "reference lines".
They then appear as nodes in your cross section. You will have to create at least on template and have to connect the appropriate nodes and assign a material. From there you can create the corridor surfaces again and start computing volumes.
Hope that helps a little bit.