I live on a hillside and due to the road being narrow large trucks and school buses use an old driveway to turn around. My problem is that every time it rains it tends to wash the gravel away and sometimes on to the top of the road. I am looking for a recommendation for fixing this issue. Currently, there is not significant ditch cut into the ground because the lot is full of large boulders and rocks. With these large boulders I do not have the equipment to dig them up and/or move them myself. Suggestions?
One of the things I have done in the past with crushed rock driveways is pack it with a roller or plate compactor until there is no movement, then use some Portland cement on the surface and broom the surface so the cement gets in the cracks, this is not a big area but with a bus or other heavy equipment using it the cement (dry powder) swept in and a light sprinkle with water will help it hold. As an example my last home 1 of the driveways dropped 30’ in 70’ steep. It was crushed quarry. I used several bags of Portland cement it never washed out and really stayed in place quite well for many years.
Some of the stone in the foreground looks maybe as large as 1-1/4 inch, but the stuff on the road looks like maybe 3/4 and smaller. Runoff could be carrying it there, but it might also be tracked out by vehicle tires.
Larger stone would stay in place better -- you could try topping this with 2 inch gravel.