RedRocker,
I found a link years ago to Amocco which is one of the makers of geotextile fabric. Google should help. I have a local supplier who sells rock, mulch, culverts, etc that also has the fabric.
The fabric comes in various widths. I have a roll of 3' and a 12-13' roll. I think they are both the same length. The wide roll is 360' long. My supplier charges me $300 a roll. The last roll I bought may have been $320. I just figure a dollar a linear foot.
Why use fabric? The fabric prevents the gravel from being pushed into the soil. I built a 500 foot drive way with fabric. In most places I would guess the gravel is only 3-4 inches think. In some places its much less. The drive handled multiple cement trucks, logging trucks, dump trucks, a small dozer, tracked execavator, as well as the various other supply trucks and contractors without a problem. I had planned on adding gravel after the house was built but the drive held up perfectly fine so we spent the money else where. /forums/images/graemlins/grin.gif
If I put down gravel, I put down fabric first.
The only downside I can see in fabric is that you have to be careful if you regrade the gravel. If you hit the fabric you will pull it up and make a mess. Not fun. I did this a couple of times when building the driveway. It means you have to get off the tractor and grab a shovel. I have no need to regrade my driveway though so its kinda a moot point. I will add gravel to fix a low spot caused by settling in a trench but that is the only reason I need to add gravel.
I have had to regrade the road a couple of times but not the drive....
Later,
Dan