As Dennis says, this can be far more complicated than just digging 2 ditches. Where I live there isn't 100' of flat land, all rolling hills.....
But, if your land is truely flat, you would be far far ahead to raise the road. Very flat land makes it hard to make the water run away, and any little dip in the topography will make a pond on your road.
It's really nice to have the road up at least 2 feet, or the ditch down 2 feet, or a combination. This will let your roadbed dry out fairly quickly, even in long rain conditions. Any less and the roadbed will saturate & compress itself with traffic & sink on you.
If you have sandy gravely soil, you could move the soil in & up, creating your ditches & raised road at the same time. Rarely does that work well tho, with organic content of the topsoil & it's usually not gravely enough. It just becomes smeary mud every little rain.
Me, I would figure out how to raise the road some at least, get gravel in for the top, get solid hard clay for a bit of a rise.
The ditches could pretty easily be made with a molboard plow & a loader - or box blade. Plow down one side, up the other, & scrape the loose dirt away with the loader. Repeat if the 7-9" isn't deep enough. You will get a lot of dirt, any plans for it? Haul it away, stack it somewhere, fill someplace? Just ridged out to the side & it will create as many problems as it solves.
--->Paul