Slope of a driveway in direction of travel

[MMagis]

This isn't a good picture, just a shot of some storm damage a couple years ago. The red line represents the driveway, approximately. It actually get's a good bit steeper at the top, but even the red line is beyond 15%. The biggest challenge for me is heavy snow. You don't have to worry about that, so you'll just have to deal with heavy rain. The biggest thing is to have a good base and have it sloped to the side so water runs off into a ditch quickly, rather than down the middle of the driveway. Other than that, it's just a matter of smoothing with a back blade on occasion. Visitors don't like it, but I figure it keeps some of the undesirables away.

 

[DKCDKC]

I've used a string level - cheap at many hardware stores - and a 50 foot tape. You make allowances here and there, and get a pretty good idea. I have found too that a brief incline over 15 degrees is tolerable if not too long, but you still have washboarding and erosion to deal with.

By the way, crushed asphalt is also good on hills in resisting washboarding and ruts... But you must apply it right and roll it down early in the summer and let the summer sun settle it down. I have friends who've used it very successfully. I did not because - with all the ice we've gotten recently - I wanted the better traction you get with gravel. Winter's a killer on my drive, tractor or no.

 

[s219]

If you have an iPhone, check out the Theodolite app -- you can try the free version and probably get what you need. It will do most of what you can do with a surveyor's transit/theodolite, and measuring slopes is a snap. You have to upgrade to the paid version ($4) to get % grade, but the free version will give you the angle in degrees which can be converted to % grade with some simple trig/math.