Measure the fence height, multiply by the drift-length factor for your design, and set the fence that far upwind of the road. The setback is the design; the fence is the easy part.
How far from the road to set a snow fence
window SNOW SEASONchecked 2026-09-16responsible Windrow Field Manual (a named masthead, not a person)
What you need A tape or a survey rod; the fence height; the wind direction the site actually gets; the drift-length factor from the design guidance.
[['1.2 m', '15–20 m', 'A small drift, enough for a short fetch'], ['2.4 m', '30–40 m', 'The common highway case'], ['3.6 m', '45–60 m', 'Large capacity; needs land you may not control'], ['Living fence, 2 m', '30 m or more', 'Same arithmetic, and it grows']]
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Steps
- Measure the fence height above the snow surface it will stand in, not above the ground.
- Look up the drift-length factor for the fence type in the design guidance. It is a multiple of the height, and it is not the same multiple for every fence.
- Multiply. That is the distance from the fence to the far end of the drift.
- Set the fence so the drift ends before the road, and check the prevailing wind direction on the site rather than on the map.
- Mark the setback on the ground and record it. The next person to move the fence will not re-derive it.
The four ways a correct fence still fails
| Failure | What went wrong | Fix |
|---|---|---|
| The drift lands on the road anyway | Setback was measured from the fence, not to the far end of the drift | Add the drift length to the setback, not half of it |
| Snow arrives from a second direction | One prevailing wind was assumed | Add a second fence, or accept reduced performance |
| The fence fills in and stops working | Capacity was exceeded in a heavy year | Increase height, or clear the fence line |
| The fence is in the right place and the road still drifts | The road's own embankment is the source | Treat the road profile, not the fence |
Why the drift-length factor is the whole job
The fence is a wind-speed reducer. Where the snow lands is a function of how far downwind the speed stays low enough for deposition, and that distance scales with the fence height. Everything else about the fence is a detail by comparison.
The manual holds that a fence set by the drift-length arithmetic is worth more than a taller fence set by eye, and that the common failure is not a bad fence but a good fence in the wrong place. Set the distance first, then choose the fence.
Where the numbers come from
- S1GeoPAK Snowdrift Analysis Tool, Minnesota Department of Transportationsupports the snowdrift analysis used to check a proposed setback
- S2Cost Benefit, Living Snow Fences, Minnesota Department of Transportationsupports the cost-benefit framing used when a fence height is chosen
- S3BMP: Deicing Material Application and Storage, U.S. Environmental Protection Agencysupports the storage guidance that keeps the drift away from the carriageway
- S4How Do Snow Fences Work?, Road Weather Management Technical Brief, Federal Highway Administrationsupports the drift-length behaviour that sets the setback distance
One link, one document. No home pages, no search results, no bare domains.
Put this page down Put this page down when the setback is marked on the ground. A number in a document does not stop a drift.