Jack and Bore
Definition
A trenchless crossing method in which a steel casing is jacked horizontally through the ground while an auger removes spoil ahead of it. The carrier pipe is then installed inside the casing.
Conclusion
Jack and bore is the standard method for getting a utility under a road or rail crossing without opening it, and the encroachment permit usually drives its schedule.
Jack and Bore: frequently asked questions
When is jack and bore used instead of open cut?
Under highways, railroads, runways, and anywhere an open trench is not permitted or would be too disruptive. Highway and railroad authorities generally require a cased crossing under an encroachment permit, and the permit process is often the longest-lead item on the crossing.
How does jack and bore differ from directional drilling?
Jack and bore drives a rigid casing along a straight, controlled line and grade, which suits gravity sewer and large-diameter crossings. Horizontal directional drilling follows a curved path and pulls flexible pipe back through the bore, which suits pressure pipe and longer crossings where precise grade is not required.