Having a driveway work it's way around the trees sounds like a really nice way to enter your place. Unfortunately, it sometimes takes two years for a tree to die and until it happens, you really don't have a clue.
Several things that you might want to consider. With nothing there, like a road, you can easily take out the trees compared to doing so with a road in place. Once the tree is removed, you will be hard pressed to remember it. Once they are gone, they fade really fast from memory. A straight line is always the cheapest to build a road on, since it's the shortest distance.
If you are going to keep the trees in question, then hiring big equipment to do the job is always the easiest way. It's also the most expensive. Figure $100 an hour for a trackhoe of decent size that can do the job. Not knowing your area, or how much dirt you need to move, it would be easy to spend a few grand on a trackhoe.
For that kind of money, I would buy a few new chains for your chainsaw and just start cutting roots with the chainsaw. You can get a harbor freight sharpener to put an edge on the chain after you wear them out, but you should also consider the chains disposable for this type of work. It's really not that expensive to just through away the chain after you've destroyed it on the roots, espeicaly when compared to the expense of hiring it out, or in renting something big enough to cut through the roots.
Having said all that, and not knowing where you are, how deep is the top soil? In many locations, and in threads that I've read here, people tend to dig these very deep trenches for their roads, then fill them with very expensive rock. Most of the time, they dug down much deeper then then needed too, and spent way too much money on filling in the hole with rock. Then they don't build up the road bed sufficiently to allow drainage to get water off of the road.
When you design your road, the most important aspect of it is to get water off of it and away from it. Water is your enemy here and road building is all about getting rid of water. The reason for digging away the top soil is that it will continue to compact and decompose over the years. You only want to get rid of the organic topsoil. In most places, it's just an inch or two. Some places like the Pacific Northwest, it can be several feet thick. If that's the case, then you bridge the soil, you don't remove it.
Once the topsoil is removed, you build it back up again. Here, I have very good clay. Clay is much cheaper then rock, so it's what is used in all our highways, city roads and just about everything. Build up the road with clay, dirt, sand or whatever is available in your area. Just be sure to have it several inches above the surrounding land. Imagine that you are building a shallow dam to stop water. In places, you will need to put in culverts to allow the water to pass. This is part of keeping the water off of the road. Let it go under and let it go away from the road as fast as possible.
You can dig trenches along the road, and might have to. If you do this, you will cause more damage to the trees. If you just bring in dirt and start building up your road, you may very well save your trees by not cutting all the roots.
Eddie
