I have Oscar88's problem: a 1/3 mi. of deteriorating road bulldozed through alluvium in the foothills of the desert SW. Parts are rather steep. The alluvium is a mixture of rock from 1" to 12" with a matrix of sand and powdery caliche. There are a few rock shelves.
The road is eroded by rare torrential rains, wind when it is dry (most of the time) and spinning wheels, especially delivery trucks.
Over the years the road has been groomed at intervals with a maintainer (grader), which keeps cutting spoil out of the high side of the road, so making it wider and wider. After grading I would usually add 1 inch crushed rock, and pray for rain. The best time to do this is a few days before July 4th, when the Mescalero Indians do their rain dances.
The road has got so bad now, and I don't want it to get any wider, so a new strategy is in play. I am pulling spoil off the lower bank of the road with my TBL, and spreading it best I can with the FEL, filling in the wheel ruts that have developed, and building up the surface to cover the exposedrocks: this is not easy because of the larger rocks. I have to keep getting off and tossing off the larger rocks. (Lacking a source for the spoil, it would have to be trucked in.)
I'm re-shaping the road so that it drains towards the downhill side of the slope it is cut in. I have put extra material over the exposed rock shelves. (I am trying an experiment - I put come mortar mix on the rock and covered it with clean gravel, hoping it will hold the fill better.
I am puttin in a couple of broad, diagonal berms on the steeper part to supplement the side slope and help the rain divert off the road (broad berms so the small cars like my Prius don't get high-centered).
The parts I have finished are quite uneven and bumpy, because of the rocks in the mix. I'm not about to take off the backhoe to put on a blade: besides, the TBL wheelbase is too short for blade work on an uneven surface. I have wet down the surface with a hose to the extent my well and availability of borrowed hose will permit to help bind the materials.
I will complete the surface by bringing in base course and spreading it to about 3": it will cover the bumps and create a maintainable surface (this is the expensive part). If the base course is fairly dry, the driver can spread it evenly from the tailgate. Base course here is what precedes asphalt for road building, and is composed of 3/4-minus crushed rock mixed with sandy clay.
If we ever get rain (it hasn't rained for 3 months during what passes for winter here!), I'll pack the base course best I can with a truck, and if necessary add a layer of 3/4- crushed rock, or grinder fines. I hope that occasional blading and addition of a little topping will keep the road up in the future. (I have a neighbor who has an excellent blade on his ancient tractor who will help me out occasionally).
I'm close to finishing the first half of the job, having worked on it intermittently for several weeks and will be bringing the base course in soon, to prevent the material I have disturbed from blowing away.
I don't think that a layer of gravel is sufficient to hold up for more than a year when the surface is destroyed and the big rocks starp appearing and popping out. You need to re-create a sufficient depth of material that the rocks are well-covered and so that you have a maintainable (bladeable) surface. In my case it is a major project. A contractor could do it in a few days with heavy equipment, but at what cost?
I hope this gives you some ideas, Oscar.
Charlie
