A pilot bore is drilled to a designed path using a steerable head tracked from the surface, then reamed to the required diameter before a pre-fused pipe — typically HDPE — is pulled back through in a single continuous pull. For polyethylene pipe, the design, pullback load calculations, and installation procedures are covered by ASTM F1962, and equipment is generally classed mini, midi, or maxi-HDD depending on the drill's length and diameter. HDD is used across water, sewer force main, gas, and telecom or fiber installation — anywhere a utility owner needs to avoid surface disruption over a defined crossing, whether that's a highway, a river, or protected wetlands. Crossing length, pipe material, and diameter drive most of the cost on an HDD bid, and that scope detail is typically buried across the drawings and a spec section rather than called out in one place — the kind of extraction Nonlinear performs automatically when it reads a bid package, rather than requiring an estimator to piece it together manually.
Knowledge Base
What is horizontal directional drilling (HDD)?
Horizontal directional drilling is a trenchless installation method that bores a steerable pilot hole underground, then enlarges it and pulls a new pipe or conduit through — used to cross under roads, rivers, wetlands, or other obstacles without open-cut excavation along the route.
