Road base calculator for Idaho

At 6 inches of compaction, a lane measuring 100-foot by 10 feet calls for about 31 tons of road base. Long runs can build tonnage quickly, making free delivery particularly relevant when hauling 30 tons can rival the material cost. Road base uses graded crushed stone with fines and weighs about 3,000 lb per cubic yard; once compacted, it forms a dense layer beneath driveways, roads, and equipment yards. Use the same calculation for recycled crushed concrete base when the specification permits it.

Lane calculations

1. For a lane, measure along its centerline and use an average width. For pads, multiply the length and width.
2. Choose a compacted depth of 4 inches for light residential areas, 6 for regular traffic and delivery trucks, or 8-12 where subgrade is soft or equipment will sit.
3. Divide cubic feet by 27 for yards; x 1.5 for tons; leave +10% for compaction.

Coverage and lane quantities

Building a lane for winter conditions

• Remove organic material before placing base. Topsoil below the stone can force mud upward, regardless of the depth poured.
• Install woven geotextile ahead of the stone where the subgrade is wet or soft. It separates the base from water-holding clay in areas such as the Palouse or Panhandle.
• Place lifts no deeper than 4 inches, rolling each one before adding the next.
• Build a 2-3% crown outward from the centerline so rain moves to the edges rather than entering the base.
• For a neat, lower-dust driving finish, place #57 or driveway gravel on top.
• Moving 20-plus tons by hand can take a week. Include a tractor box blade or skid steer in the plan for afternoon spreading.

Worked example: a 100-foot farm lane

For one hundred by ten feet at 6 inches, use 1,000 x 0.5 = 500 cubic feet = 18.5 cubic yards, or about 28 tons, with 30-31 after the allowance. Expect two tandem loads, and set two drop points along the run instead of leaving one large pile at the gate. Splitting the drops shortens the distance needed to move material while spreading.

Equipment, container, and RV pads

Use the lane calculation for pads, but select depth by axle load instead of the calendar. A 12 x 40 RV pad at 6 inches compacted takes about 12 tons. A 20 x 40 equipment yard at 8 inches needs 27. Because shipping containers place weight on four corners, container pads need a full 8 inches plus fabric even on decent ground, helping prevent the corners from settling into the pad by spring.

Using crushed concrete for road base

Recycled concrete base can compact and carry load much like virgin road base, often at a lower cost. Check county specifications before changing materials, since some call for virgin aggregate; it can suit private lanes and pads. The quantity method stays the same: 1.5 tons per yard, with the same lifts and crown.

Road base quantities by ton and lane

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