How to Determine a Mountain Road Grade

So far, we have about three miles of road on our property. All road that we have cut ourselves up the mountain side, one bucket at the time. It is time to make a new cut, to make life a bit easier. So, we need to mark where the road should go. In this post I will show you how we determine our mountain road grade, and how the road should follow the nature on our property, using an Inclinometer (also called Abney Level).


Our property is essentially … a mountain… Well, it is actually most of a large “ridge” that goes out from a mountain ridge. On our mountain we have a LOT of brush..of course in addition to all the rocks, boulders, and trees (Pine and Aspen).  When we are making our roads, we need to plan it a bit. Although, after making about three miles of mountain road, you kind of get a feeling of what kind of grade you are in when you sit in your excavator. BUT, when you have to go through brush, trees, and follow the curvature of the nature (thorough ravines etc), it is easy to suddenly get pretty off on your grade. This has especially happened many times when I suddenly hit a boulder (or the mountain itself) and I cannot move it. Then, I have to actually make the road to go over the boulder/mountain.

When I say “plan”, I actually mean something practical that we do physically out in the nature. Let me show you how we doit.

Disclaimer: We are definitely not expert road makers, but this is the method we have chosen, and it works great for us.

The Inclinometer

According to Wikipedia, this is the definition of an Inclinometer:

An inclinometer or clinometer is an instrument for measuring angles of slope (or tilt), elevation or depression of an object with respect to gravity.

This is an image of our inclinometer:

Inclinometer for determining grade on a road

Inclinometer for determining grade on a road

The Inclinometer has two scales: Percent, and degrees. We normally use the degrees scale. Our favorite degree level is about 5-7 degrees. We are trying to plan our roads to have the kind of grade that we will feel comfortable driving up and down, even when we get old…er.

How we use the inclinometer

To use the the inclinometer, I first found a piece of 1″ x 2″, 8′ long. Then I put this piece of wood right in front of my eyes to mark on the “measuring rod” where my eye level is. Then I just wrapped some orange ribbon around the “measuring rod” at the marked place.

Road grade measuring rod

Measuring rod to help determining road grade

This is the rod that my wife brings with her when we go though the nature, where the road will end up going. Usually she goes about 50′ or so away from me with the rod.

Determining the road grade

Determining the road grade

First, I adjust the scale on the inclinometer so that it is set to about 6 degrees. I then stand still at the previous marked spot in the nature, and look through the eye-piece on the inclinometer. Inside the inclinometer there is a “hairline” going horizontally across the middle of the square front of the inclinometer. Looking through the eye-piece, I position the the “hairline” on the orange ribbon on the measuring rod my wife is holding. Then, on the instrument, there is an adjustable part with a bubble on it. Inside of the inclinometer itself there is a mirror, making it so that you can see the hairline and the bubble at the same time. If the bubble is lined up with the bubble when I look at the orange ribbon through the eye-piece, we are good to put a piece of orange/pink ribbon right where the measuring rod is. Otherwise, I have my wife go either a bit up or a bit down the slope until the hairline and the bubble are lined up.

That is basically it 🙂

Cautions, or thing to consider

This method is working awesome for us, there are some fall pits. One example is what I have tried to show on my “Louvre Museum” art below:

True road grade following curving nature

True road grade following curving nature

What I have tried to explain in my drawing above is that you cannot stand on one side of i.e. a small ravine and measure the grade straight across to the other side. It is probably completely obvious, but I still choose to mention it. If you follow your 6 degree grade along the curving nature through your “ravine”, you might actually end up with your next marker ribbon many feet  higher than you would if you measure across. Just sayin’…..

And hey, instead of “reading the book”, we actually have a Yutube video where we show and explain some of this:

I hope you have enjoyed this post. If you do, please make sure you share it on social media. 🙂

About TJ

A Senior Software Engineer - a software developer for almost 30 years. Supporter of use of sound logic, both in work and life situations. Eager to learn new things, and is not afraid of jumping into an excavator for the first time starting the work of making a three miles steep mountain road. Loves nature, and has his favorite times (when not with his wonderful wifie) in the shade during the summer listening to our Creator's nature-musicians - the song birds.


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