Railroad Ballast in Wisconsin: The Coarse Layer That Goes Underneath

Ballast gets ordered to fix ground that will not hold. A corner of the yard that stays soft until June, a pad that sank the first winter, a strip along the barn that turns to soup every time the frost lets go. Railroad ballast solves that by being too big to be pushed into wet subgrade and too angular to roll apart under weight, with gaps between the pieces that water can leave through. It is the layer at the bottom of a build, and almost every disappointing load of it was bought for the top.

Size runs roughly 1 inch to 2.5 inches, graded so the pieces lock together under load while still draining freely. Large angular crushed stone, and it neither looks nor behaves like a finished surface.

Breaker Run, #4 stone and ballast do three different jobs

The practical distinction is fines. Breaker run has them and knits into a mass. Ballast has none, so it stays a stack of stones with holes in it, which is the point.

Where a load of Railroad Ballast earns its keep on a rural property

• Under an equipment or machinery pad, where the load is concentrated and the subgrade underneath was never much good.
• Under a hot tub or shed pad on a wet site, as the layer that keeps the bottom of the build out of standing water.
• Under a side-yard run or a working corner where daily traffic has churned the ground.
• In a low spot that holds meltwater every April, as a coarse layer below the fill and soil that will cap it.
• On access routes and crossings where loaded trucks or machinery repeatedly cross soft ground.
• Rail track work, which is where the grading and the name come from.

What it is not: a finish. Walking on it is unpleasant, a mower will not cross it, and a plow blade catches it. Whatever sits on top comes from a different pile.

How deep the open layer goes, and how deep it stays

• Plan on 4 to 6 inches of ballast for a light job such as a hot tub pad or a run, and more on genuinely soft ground or where machinery will sit.
• Those are loose depths and they settle. Ballast is not compacted into a slab the way a base course is. A pass or two with a plate seats the pieces and that is all it can do, since there is no binder to lock.
• On soft, wet or peaty ground, put a woven geotextile between the subgrade and the stone. Without it the stone presses into the mud and vanishes, and you will be paying for the same tonnage twice.
• Cap it. Compacted traffic bond over the ballast is what gives you something that can be graded, walked on or plowed.
• Keep the whole layer above the level water sits at, and give the water a way out. Frost under pavement can reach 48 to 72 inches by late winter here, and an open layer with no outlet is a reservoir.
• Cut the excavation to the full depth of the stone plus the cap, rather than mounding the stone on top of existing grade.

Tonnage for a soggy lawn corner, a hot tub pad and a 30-foot run

Length times width times depth in inches divided by 12, then divided by 27, gives cubic yards. This site's calculators list #4 stone and railroad ballast at about 2,900 lb per cubic yard, which is 1.45 tons per yard.

• Example, a wet lawn corner 20 ft by 25 ft taking 6 inches of ballast before it is filled and topped: 500 square feet x 0.5 = 250 cubic feet, divided by 27 = 9.3 cubic yards, times 1.45 = about 13.4 tons.
• Example, a 7 ft square hot tub pad with an 18 inch margin all round, so 10 ft by 10 ft, at 6 inches: 100 square feet x 0.5 = 50 cubic feet, divided by 27 = 1.85 cubic yards, times 1.45 = about 2.7 tons.
• Example, a side-yard run 8 ft by 30 ft at 4 inches: 240 square feet x 0.333 = 80 cubic feet, divided by 27 = 2.96 cubic yards, times 1.45 = about 4.3 tons.

Working the other way, one ton is about 0.69 cubic yards, or 18.6 cubic feet, which covers roughly 37 square feet at 6 inches and 56 square feet at 4 inches. Those are approximate, and every one of the three examples above needs a separate calculation for its cap. The stone calculator will run the tonnage if you would rather enter the measurements.

Picking a date once the frost is out of the lane

Ballast work belongs in the window between the end of the thaw and freeze-up, because you cannot shape or compact anything over frozen ground, and because placing stone on saturated subgrade wastes it. Class II state highways and posted county, town and village roads carry spring weight limits while the frost comes out, and in the northern zones those lift later than they do in the south, so a loaded truck heading down a posted town road in April may want a later date.

Before the delivery: mark the dump spot, check the truck can reverse out of it, and have the excavation cut and the fabric down. Delivery is arranged at checkout from your ZIP code. Set your tonnage and a date on this page, or send the site measurements through the contact form if you want the layer depths looked over before you commit to a quantity.