The first Horizontal Directional Drill was used in 1971 to cross 550 meters gas pipeline under a river in the United States. Then, in Germany in 1986, through the crossing a power line and a pipeline by HDD method. Later, development of the crossing techniques and equipment helped increasing and improving the capacity of the drilling machine, and this method has reached its peak, as currently in the US, Europe and East Asia major projects for the crossing of underground electrical and fiber optic cables and water splits, Gas and oil and oil are being done by this mean due to the undeniable benefits of this method including extraordinary accuracy, speed of opratin, cost savings, eliminating disturbing parameters in urban environments, and extraordinary environmental benefits. The number of H.D.D projects operatin in advanced countries is increasing every year.In Iran for the first time in 2005, HDD technology was used to transport 12 fields of oil and refinery products from Abadan in sizes from 8 to 36 inches below the Behmanshir River in Abadan. In this project, the technology was completely indigenous and its implementation was carried out by Iranian experts.

Horizontal Directional Drilling helps cross oil, gas, water, all power lines, telecommunications and fiber optic pipelines below following bariers. In sea Crossing generally, there is an island near the beach and crossing water, gas, oil, electricity, telecommunications pipes or optical fiber is nessecery, this method is one of the safest, fastest and most effective methods.

• rivers
• roads
• railways
• Buildings and facilities
• Other obstacles
• Crossing pipelines at sea

Horizantal directional drilling steps are as below:

• Drilling the Pilot Hole



• Reaming



• Pulling the pipe