Driving to Perfection

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The safest approach angle from road to drive is a flat 90°. The opening into the road should flare gradually and evenly on each side so that it will at least double the drive's width. This will allow for easy turns in and out. Stake out both sides of your entry in fair curves by setting out stakes every five feet. Then run a stake line up the center of the drive — stakes every 20 feet on the flat, every six feet around curves, and at the top of all nobs and knolls.

The rules are simple. Try to maintain a constant fall — as uniform a grade as possible — of between two and five percent. To maintain grade on a steep slope, run the drive back and forth along the face of the slope, doing your best to locate curves where the hill levels out. If you must contend with a steep rise, try to have the sharpest portion of the grade at the top of the drive (so you can make a running start to crest it in slippery weather).

To gauge grade, have a helper run the line out 50 (or 100) feet and place it on the ground. Attach the line level, pull the line tight, and level at your marked stake. If the line hits the one-foot (2') mark you have a two-percent grade; at the 2 1/2 ft (5') mark you have a five-percent grade.

Use the 24- and 48-foot marks on the line to lay out curves. Describe both size circles on flat land to get an idea of the extremes, and estimate them out on the land, checking later with the line (placed at the imaginary center of the circle described by your curve). Make the curves as fair — as near to the arc of a perfect circle — as you can.

As you encounter low nobs and shallow dips, run the line along the top of the rises. The road will be evened out as nobs are cut and dips are filled with the spoil. If a driveable grade or a fair curve requires cutting out the side of a large soil bank, the spoil can be used to fill dips or extend the roadway off to the side. The bare soil walls can be planted with trees and grass or buttressed with a terrace or retaining wall. (See illustration "Cuts and Fills" ) Terraces and retaining walls can be built out of timbers, rock, or of precast, interlocking concrete posts. But every cubic yard of spoil taken out must have somewhere to go, and its removal takes time and money. Every layer of fill needs compacting — but may still settle and need to be topped up. Avoid as much subsoil removal as you can, even if it means a longer drive.

Paving a Clear Way

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