The Horizontal directional drilling technology nowadays is an integral part of pipeline construction projects.The innovative trenchless HDD technology with its environmental and economical advantages is mainly applied for crossings underneath rivers and traffic ways, flood protection dams, foundations of buildings or infrastructure objects, topographic obstacles like rock ridges, orthogonal situated hills and rims, non-crossable terrains and nature reserves, parks or even hole city areas or mountain zones.
But HDD rigs of different size and type are also used for pipeline installation projects of different lengths, depths, curves, geology as well as technical and environmental conditions. For installing pipelines over longer distances (middle to high pressure pipelines) HDD machines from the 35-t-class up to the largest units in the HDD market are applied. Nearly all obstacles along pipeline traces like rivers, lakes, mountain ridges, traffic lines such as railways with highways and roads can be overcome with the HDD technique, thus open river crossings or open crossings of traffic lines get out of use for environmental and economic reasons
The paper presents the technical application aspects of the HDD technology in principle and the wide application range with a focus on maxi and mega rigs which are employed for installing supply and sewer pipelines over longer distances (middle to high pressure pipelines).
Using several practical examples of HDD pipeline projects in Europe the technology is described in detail including some video sequences.