Gravel & Aggregate
Gravel Road Construction: Layers, Tons per Mile & Cost
A gravel road is not a long driveway: it needs a crowned profile, ditches, and 6-12 inches of stone in layers. Tons per 100 feet and per mile, cost per foot, and the maintenance cycle.
A gravel road is a drainage structure that happens to carry vehicles. The stone gets the attention, but the crown and the ditches decide whether the road lasts: water standing on or under gravel is what makes potholes, washboard, and mud. Here is the tonnage math, the profile, and the budget for farm lanes, long rural drives, and access roads.
Tonnage: the numbers that matter
| Road width | Compacted depth | Tons per 100 ft | Tons per mile |
|---|---|---|---|
| 10 ft | 6 in | ~21 | ~1,100 |
| 12 ft | 6 in | ~25 | ~1,310 |
| 12 ft | 8 in | ~33 | ~1,750 |
| 14 ft | 10 in | ~48 | ~2,550 |
Run each layer separately in the gravel calculator (different stone, different depth), and plan deliveries as full tandem or tri-axle loads: at these volumes, per-load freight is the whole price game, as the truckload guide shows.
The profile: crown and ditches
Crown: the centerline rides higher than the edges, falling about 1/2 inch per foot of half-width (4%). A 12-foot road crowns 3 inches. Water leaves sideways immediately instead of running down the wheel tracks.
Ditches: a shallow V or trapezoid on each side, 12-18 inches below road edge, falling continuously along the road's length to a culvert or outlet. The road sheds to the ditch; the ditch carries it away. No ditch, no road, just a long puddle with gravel in it.
Culverts: wherever the ditch must cross under the road or a driveway entrance, a 12-15 inch pipe with stone armor at both ends. Undersized culverts are the number one washout cause.
The layer stack
Identical philosophy to driveway layers, with heavier duty: 4 inches of large clean base stone (#2-#3) on compacted subgrade (over geotextile on soft or wet ground, non-negotiable in clay country), 3-4 inches of crusher run compacted to lock, and 2-3 inches of surface course with fines, graded to the crown. Build and compact one layer at a time; a single 8-inch dump never densifies.
2026 budget per 100 feet (12 ft wide, 8 in, materials)
| Item | Quantity | Cost |
|---|---|---|
| Base stone | ~15 tons | $225-$450 |
| Crusher run | ~11 tons | $165-$330 |
| Surface course | ~8 tons | $120-$280 |
| Geotextile (soft ground) | 1,200 ft² | $360-$700 |
| Materials total | $510-$1,060 (+fabric where needed) |
Add delivery by the load, machine time or contractor grading, and culverts. Per-ton pricing by material is in the price guide. Contractor-built all-in figures of $8-$25 per foot assume normal ground; rock cuts, wet subgrade, and long freight change everything, so quotes beat rules of thumb past the driveway scale.
Maintenance is part of the design
Gravel roads are re-shaped, not repaired: once or twice a year, a grader blade or tractor box blade pulls material from the edges back to the crown and cuts washboard before it hardens into the base. Every 2-4 years the surface course gets a topping lift. The budget line that owners skip, and the reason two identical roads age completely differently, is this cycle plus keeping the ditches open. Crown, ditch, regrade: everything else is commentary.
Sources & standards: quantities and factors in this guide follow the references documented in our methodology, including ACI 302/318 (concrete practice), OSHA 29 CFR 1926 Subpart P (excavation safety), ASTM aggregate designations, and the International Residential Code. Local codes, climate, and site conditions govern.
Frequently Asked Questions
How much gravel do I need for a road?
A 12-foot-wide road with 8 compacted inches of stone needs roughly 33 tons per 100 feet, or about 1,750 tons per mile. At 6 inches, figure 25 tons per 100 feet. Use the gravel calculator with your width, length, and depth per layer.
How much does a gravel road cost per foot?
Materials alone run $3-$8 per linear foot for a 12-foot width in 2026, delivered. With grading, ditching, culverts, and compaction by a contractor, $8-$25+ per foot is typical; difficult ground and long hauls push it higher.
What is the crown on a gravel road?
The center of the road sits higher than the edges, falling 1/2 inch per foot of half-width (about 4%), so a 12-foot road crowns 3 inches. Without crown, water runs down the wheel paths and cuts potholes and washboard.
What gravel is best for a road?
Same recipe as a driveway, scaled up: large clean stone base (#2-#3), crusher-run middle, and a surface course with fines that binds when compacted. Rounded river gravel never locks and stays loose forever.
How often does a gravel road need grading?
Plan to re-crown and knock down washboard once or twice a year, plus a surface topping every 2-4 years depending on traffic. Well-built crown and ditches double the interval; poor drainage halves it.