Predictions show that the global horizontal directional drilling market will reach a value of $14.86 billion by 2028.

These days a lot of services and utilities operate using underground pipelines, and one of the methods for installing them is horizontal drilling. But What is HDD exactly? And why is it beneficial?

For a rundown of horizontal directional drilling (HDD), keep reading.

What Is Horizontal Directional Drilling?

HDD is a method of drilling for the installation of pipelines, cables, and service conduits. This is often done in cases where trenching or excavating is not suitable, often under waterways or other designated areas.

This is ideal for different soil conditions/jobs and is capable of pulling the pipeline through the final hole. These pipes are generally made of a variety of materials:

  • Steel
  • Iron
  • Polyethelene
  • Polypropylene
  • PVC

The process uses a directional drilling machine.

The Process

HDD is the chosen method when environmental and stakeholder impact needs to be kept to a minimum.

This pipeline drilling process consists of three main steps.

Pilot Hole

A pilot hole is first drilled and drilling fluid is simultaneously pumped through the drill bit. This fluid carries debris back to the entrance pit throughout the process.

An underground magnetics transmitter can detect and locate any existing conduits such as pipelines in the ground that could interfere with the drilling process.

The scale and complexity of the job determine how the pilot hole is tracked. Walkover guidance systems are ideal for smaller shots, but more complex shots will need a wireline magnetics system.

A transmitter provides the coordinates of the drill stem ensuring everything is on track in terms of alignment, depth, and percent slope.


This involves enlarging the pilot hole so that it is large enough to properly install the product lines. This is done with a reamer, and at the same time, it will pump drilling fluid to remove solids as it goes.

The soil conditions and the amount of debris will affect how long this takes. Special additives such as bentonite and polymers help break up the soil and make sure the hole is stable and clean.

Pipe Pullback

After the drilling, the workers will pull the pipe through. The reamer and drill rod are attached to a swivel that prevents torsional stress between the rotating drill string and the product pipe.

Throughout this process, more drilling fluid is constantly pumped through to lubricate the pipe.

When To Go Trenchless

Pipelines are typically laid by digging trenches in open areas, but if that is not an option this method will perform the task while reducing the impact on the surface.

HDD may need to be best if the installation is:

  • Over five feet deep
  • Over 180 feet long
  • Below the water table
  • Soil is unstable
  • Other services/utilities are underground
  • In a residential area
  • In an urban area
  • Below rivers, roads, or railways

Is Horizontal Directional Drilling The Best Choice?

Horizontal directional drilling is generally the best solution if two or more of the factors above are true. Not only is it the best solution, under those circumstances, it is also cost-effective and requires less equipment and manpower than other methods.

If you’re interested in more technology and how-to articles check out some of our other blog posts.

By Hemant Kumar

I am a zealous writer who loves learning, redesigning the information, and sharing the original content in an innovative and embellish manner. I hope you will find my work beneficial and entertaining. Happy Reading!