Road base calculator for Hawaii

A lane measuring 100-foot by 10 feet at 6 inches after compaction calls for about 31 tons of road base. Tonnage builds quickly on a lane, and free delivery is especially relevant at 30 tons, when hauling can otherwise rival the stone cost. Road base combines graded crushed stone and fines at about 3,000 lb per cubic yard, forming a dense layer below roads, driveways, and equipment yards. Where specifications permit, recycled crushed concrete base uses the same calculation.

Lane calculations

1. On a lane, take the centerline length and apply its average width. For a pad, multiply the length and width.
2. Use 4 inches compacted for light residential use, 6 for regular traffic and delivery trucks, and 8-12 on soft ground or beneath equipment.
3. Divide cubic feet by 27 for yards, then x 1.5 for tons. Add 10% for compaction.

Lane coverage and tonnage

Building a lane for heavy rain

• Remove organic material before placing the base. Topsoil beneath stone can pump mud upward regardless of how thick the layer is.
• Put woven geotextile over soft or wet subgrade before placing stone. It helps separate the base from saturated soil beneath a lane.
• Install and roll lifts at 4 inches or less before adding the next layer.
• Slope the finished surface 2-3% outward from the centerline so rain moves off the lane instead of into the base.
• For a clean driving surface with less dust, finish with #57 or driveway gravel.
• Hand-moving 20-plus tons can take a week. Include the cost of a skid steer or tractor box blade, since either can spread it in an afternoon.

Worked example: a 100-foot lane

At 6 inches, a lane one hundred feet long and ten feet wide comes to 1,000 x 0.5 = 500 cubic feet = 18.5 cubic yards, or about 28 tons and 30-31 with the allowance. That is two tandem loads. Set up two drop areas along the lane instead of leaving one large pile at the entrance. This makes spreading easier, especially where the run slopes downhill.

Pads for equipment, containers, and RVs

Pad calculations use the same method, but select depth based on axle weight rather than time of year. A 12 x 40 RV pad at 6 inches after compaction needs about 12 tons. A 20 x 40 equipment area at 8 inches takes 27. Containers put their load on four corners, so use a full 8 inches with fabric below container pads, even where the ground seems decent, to keep corners from settling into the pad during wet weather.

Crushed concrete road base

For private access areas, recycled concrete base is often a lower-cost alternative to virgin road base, with similar compaction and load support. Review county specifications first, since some call for virgin aggregate. Use the same crown and lift approach, with 1.5 tons per yard.

Road base by ton for each lane

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