Direct Pipe as an Alternative to HDD, Method and Case Studies
Annual Conference
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This paper provides an overview of the multiple case histories of the Direct Pipe technology worldwide. Thereby illustrating the benefits for the owner, engineer and contractor in comparison to HDD in permeable soil conditions.
The Direct Pipe method has been first used in 2007 at the Rhine river crossing in Worms, Germany. Since then, more than 18 crossings have been installed in Europe and the US with great success. The longest installation so far had a total length of 4,600ft (1,400m) and a pipeline diameter of 48”. The peak performance during that installation was 756ft (232m) per day (24hrs).
Since its inception Direct Pipe has been adopted for the installation of over 30 crossings in numerous European countries and further afield such as America, Canada and Thailand.
To date all attempted installations have been successful.
The largest pipeline currently installed is a 56” steel pipe in Preston, England with a total length of 2,820ft, serving as casing pipe for a post installed 36” potable water pipeline (HDPE).
The combination of the well established Microtunneling technique with the Pipe Thruster technology makes it ideal for difficult (permeable) soil conditions which pose a certain risk for frack-outs using the HDD method, and this paper intends to highlight the benefits from operational, construction programme and risk mitigation aspects.