Jon RobisonGeoEngineers recently suggested that one of our long-time energy market clients consider Direct Pipe™ (DP) for a difficult interstate highway pipeline crossing. DP is essentially a curved or directional microtunnel that utilizes proprietary equipment developed by Herrenknecht Tunneling Systems in Germany. Less than 20 of these installations have been made in the world (most of these in Europe) and the technology and engineering analysis surrounding it are evolving rapidly.
The system combines elements of traditional microtunneling and horizontal directional drilling (HDD); it allows for a fully supported tunnel (unlike HDD) and unlike traditional microtunneling the drill path is curved, allowing the depth of entry and exit pits to be significantly reduced. Because the drill path is fully supported, it can be installed at much shallower depths compared to HDD. This allows also for significantly shorter installation distances.
We are excited about this technology! We are now most of the way through the geotechnical exploration and getting into the detail design of the crossing—so far all the results and analyses, including initial construction budget discussions, are positive. Stay tuned, I hope to have more on this project as it continues to develop.