Railroad Ballast: The Coarsest Stone Sold Here

Stand next to a dropped load and you can see the difference without measuring anything. The pieces are fist-sized and bigger, every face is a fresh break, and the pile holds a steep angle instead of slumping out flat the way a finer stone does.

Push a boot into it and nothing much happens. That is the point of railroad ballast: the pieces lock against each other, and the gaps between them stay open.

What the railroad ballast spec line actually reads

Three figures describe it, and everything else follows from them.

Size is what lets it bridge soft ground. Angular shape is what stops it rolling under a load. The open grading is what keeps water moving through the layer while that load is sitting on it.

Note what is missing from that list. There is no fines content, so it does not compact into a tight surface and it never will.

A boat pad, a wet lane and a garden path, side by side

Three jobs a camp owner might consider it for. It suits two of them.

The lane case is the one worth being careful with. Use it where the ground is genuinely soft. On firm valley outwash it is more stone than the job needs and #4 Crushed Stone will do the same work.

Mud season, ledge and water with nowhere to go

The reason this size exists in a New Hampshire yard at all is the thaw.

Till soils hold water on top of ground that is still frozen. For a few weeks the surface carries nothing, and any pad or lane without its own drainage route goes soft under whatever is parked on it.

A coarse open layer takes that water sideways. It also gives the load a skeleton of stone that is too large to be pushed down into soft soil, so the pad stays where you built it.

Around the lakes and up in the hills there is the other half of the problem: ledge close to grade, nothing to excavate into, and a build that has to go upward. Coarse stone works there too, because a layer sitting on rock still needs voids for the water that runs across the rock face.

Put geotextile between stone and soil every time. Fines working up into the voids is the one thing that ruins this material.

Tonnage for a 12 by 40 boat pad, a 120 foot wet stretch and a path that should be something else

Three hypothetical jobs. Ballast runs about 2,900 lb per cubic yard on this site's published figures, near enough to 1.45 tons per cubic yard.

Boat and trailer pad, 12 ft by 40 ft, 6 inches

• 12 x 40 = 480 sq ft
• 480 x 6 / 12 = 240 cu ft
• 240 / 27 = 8.89 cu yd
• 8.89 x 1.45 = 12.9 tons, order 13

Wet stretch of lane, 120 ft by 10 ft, 8 inches

• 120 x 10 = 1,200 sq ft
• 1,200 x 8 / 12 = 800 cu ft
• 800 / 27 = 29.63 cu yd
• 29.63 x 1.45 = 43.0 tons

That lane then needs a compacted course of crushed gravel over the top before anything drives on it. Budget for both loads.

Garden path, 60 ft by 3 ft, 3 inches

• 60 x 3 = 180 sq ft
• 180 x 3 / 12 = 45 cu ft
• 45 / 27 = 1.67 cu yd

Order that in Stone Dust at about 2,900 lb per cubic yard, or in Pea Stone, not in ballast. Either one gives you 2.4 tons or thereabouts and a path you can walk on.

The stone calculator will take other dimensions.

Landing a heavy load at the end of a narrow camp road

Set the quantity and choose a delivery date here. Delivery is arranged at checkout by ZIP code.

Ballast is the most awkward material on the list to move after it lands, so the drop spot matters more than usual. Get the pile onto or beside the work if the truck can reach, and have machinery ready rather than planning to wheelbarrow it.

The truck wants firm ground, room to back and clear height to raise the body. On a camp road the overhead branches are usually the problem, and the time to cut them is before the load is booked, not while it waits.

If the lane you are fixing is the same lane the truck has to use, think about the order of work. A pile at the firm end and a bucket beats a tandem sitting in the soft stretch you were trying to fix.