Horizontal directional drilling technology


Passing under roads, railways, engineering facilities, canals, rivers and others, overpassing existing underground communications during the construction of: 

  • gas and water pipelines, sewers and others
  • casing pipes
  • drainage lines
  • cables with enough tensile strength

The length of the drilling can reach from few tens of meters to over 1500m, and the diameter – from 100mm to over 1500mm.


Technology advantages

Low costs due to the high productivity and precision of the method for installation of pipes and cables – only start and end shafts with minimum size are necessary.

Suitable pipes


HDPE, PP, PVC pipes

Steel pipes

Electrical or communication cables with high tensile strength


Technological Process

Pilot drilling

The process starts with a pilot directional drilling with small diameter following the preliminary set path from the machine to the end shaft. The drilling is implemented by a drilling head, using a drilling fluid under pressure. Control is provided by the non-symmetrical shape of the drilling head in combination with progressive rotary motion and orientation of the head in the space. The position of the head is controlled by an electronic system, consisting of a transmitter, located in the drilling head and a receiver, located on the surface.

Enlarging (reaming) of drilling

After the drilling head reaches the end shaft, it is demounted, and the so-called back reamer is installed on its place. The machine pulls back the reamer by a progressive rotary motion and enlarges the diameter of the tunnel. A drilling fluid is fed through the back reamer, the purpose of which is to take out the soil particles and stabilize the tunnel. Depending on the size of the installed pipe, several intermediate reamings may be done, until the required diameter of the tunnel is reached. 

Pipe installation

After the required diameter of the tunnel is reached, a grapple for pulling the pipe is attached to the reamer. After that the pipe is pulled in the tunnel. The drilling fluid (composed by fine soil particles, bentonite and water) fills the space between the pipe and the tunnel walls, providing an effective pipe protection.