Advice Sought on Cutting Correct Slope on Hillside Roads

[Allan M]

I'd like to tap into those experienced operators on this site and get some pointers. I have about 350 hours logged in on my Kubota 6.5 ton excavator (so I'm relatively new at this gig). I've also cut about .75 miles of trail with some wide enough for a 4x4 truck to use and some cutting through heavy trees, brush and on steep hillsides. I seem to have great difficulty cutting the correct slope--sloping the road toward the uphill side to prevent water damage in heavy rain. I'll need to go back and finish cut all of the work that I have done thus far in order to get the correct slope.

I'm curious about the tips and techniques that experienced operators use in order to cut a correct slope toward the hill. Input would be appreciated. As you can see in this pic the road is slightly sloped toward the downside of the hill. It seems as though I can't cut it right the first time.

Thanks. Allan

 

[CM1995]

How much of the right side of the road in the pic is fill and how much is on cut?

 

[Allan M]

The cut side on this road varies from 3' to 5'. I'd say that the fill side is about 1' to 3'. The soil here is rocky serpentine (decaying rock) and seemed to lock in place and hold well on the fill side. This isn't the case in some other areas further up the mountain. I did get into flour soil and clay where I was cutting much deeper on the cut side (especially where steep) to get to virgin soil on both sides of the road.

 

[Don.S]

Put dirt under the low side track to bring it up to the same angle you want the road to be

 

[skyking1]

The down side will always go down on you. Do as Don said. ^
When you have a machine without tilt, you need to exaggerate the fill on the down hill side to form about a 4% slope back.
I doze forward with the excavator an take from the up side and place it on the down side with the bucket as I go.
This will pound down and settle. You can tune it up later after it compacts.
Now you have created a ditch that will gather water and destroy your road that way too, so you need to plan and manage getting the water off the downhill side in control. Sometimes you have the right logs to put in some cross logs at a low spot to get the water over there without washing the road out.
You need to keep managing that water as it goes down the hill so you don't mess up your property.
One technique is kicking it off the road in areas with shallower slopes. Rocks and brush from the road clearing process can also be used to slow the water down.

 

[Allan M]

Thanks for the input Don S. and skyking1. I guess I will put on a bigger bucket (I'm using an 18" for the initial cut) and go back over my work and adjust the slope that way. I was also thinking of using my compact tractor and box scraper to modify the slope of the road (I can angle the box scraper relative to the slope of the hill as you guys know). I think the box scraper and lighter machine might struggle on the rocky soil areas that I've cut further down the mountain--but might do okay on the clay/lighter soil further up the mountain. I must admit, it is amazing how much work a 13k pound machine will do. In tough areas I might make 50' an hour cutting new road; in easier areas (no trees or big rock obstacles) I might make close to 100' feet an hour--and some of this work is on the side of a hill that would be difficult to walk up given steepness. It must be a real power trip to drive a big-boy machine of 30k plus pounds. Not many obstacles would slow you down.

 

[Willie B]

A road half cut, half fill will be pretty unstable. If you get frost or wet season it may slide a bit. As the State of Vermont learned (or failed to learn) it'll be in constant motion. Route 4 in Woodstock gets repaved about every two years & is smooth only a few months each pave.

Only way to prevent this is dig down where the whole roadbed is over cut soil. Then depending on budget, drainage goes in at lowest level. Build it back up with what you can afford.
Angle of repose dictates your bank angle. dig far enough it doesn't fall in heavy rain.

I'd like to see a ditch on the uphill side, and plenty of water bars to bring water to downhill side. If you don't plow snow, old belting buried with a few inches sticking up makes a slick water bar.

 

[CM1995]

Not familiar with your soils but soil in general works the same for what you are doing. The fill side will compact and settle as more weight via equipment and other traffic pounds it down. The soil on the fill side needs to be compacted to 95-98% of the natural soil. Don't fret on the numbers when it gets in the 95-98% range it will be hard. The way to do that with what you have is what other's have suggested and keep filling the low side until you get the desired pitch back towards the slope. Just keep the fill lifts thin and track over it again and again.

Again not familiar with your soils but we build roads all the time on slopes with a cut on the high side and a fill on the low side. If you have a deep fill on the low side you can trying keying in the slope as you fill - basically cut stair steps back into the existing slope and bring compacted fill back up the "stairs". This is a common practice and required in most spec's for the commercial jobs we do.

If possible you may want to make your road wider in the steeper areas so you can stair step the fill in with your mini and get better compaction.

Depending on your budget you might want to look into some HDPE pipe commonly manufactured by ADS for getting water from the ditch on the high side under the road and down the slope. HDPE is relatively inexpensive, tough and easy to work with. Depending on your rainfall amount 12-15" diameter should carry the water fine. We've been using A2000 PVC as it's been spec'd on the last few jobs which is an equivalent to ADS but I don't like it as much as ADS. The A2000 is more brittle where the ADS is more flexible and can take more abuse. ADS would work better IMO for your situation.

If you decide to use pipe across the road save your basketball size rocks for outlet protection on the downhill side of the pipe to keep erosion down. You look like you have an abundance.