Damn buddy you got real problems there sheesh...I'm watching this thread closely. I have one neighbor, a retired 6th grade school teacher that is 275 yards away but we share a driveway that is 3/10 mile long with 1/10 mile of it a very steep grade. I'm at the end of the driveway. My acreage is graded to drain across and under the asphalt driveway we had installed to the edge of our property line. Her private gravel drive intersects the common gravel driveway with her entire property draining rain water to the shared road which is at the very top of the steep grade down the hill.
We have lived here for 30 years with the first two neighbors being more than happy to share expenses and work to maintain the road, add gravel so it could be crowned and drain to the ditches, etc.
When she moved in, we greeted her and talked about how difficult the road maintenance was and volunteered to maintain it if she would share in cost of gravel. She commented nobody informed her that she would have to pay for road maintenance when she bought the house.
So, 6 months and several rain storms later with the road getting in bad shape, asked if she was willing to contribute to a couple semi's of gravel. Absolutely not was the reply. So we bought them and fixed it. We again had to buy a couple semi loads a year later with no help.
The road is now a big bowl with water running down the center from her yard only and washing it down to bedrock in places after these huge rains.
We will be out thousands of dollars for gravel just on the steep portion. The lower portion of the driveway that is flat has 5' of the Arkansas river with a swift current flowing over it for a week now with at least another week expected of maximum flows at best. No telling how much road has washed out there until the water goes down.
