At the beginning of the century, two offshore gas fields were discovered off the coast of Victoria (Southeast Australia). Their development is the mission of the "Otway Bay Projects". The gas fields were to be connected with the onshore processing plants by a pipeline that had to be installed unerground under the coast line.
The HDD rig to be used for the pipeline installation required a "start-up aid" because it could not start working in the in the initially unstable geology of sand and gravel. A retractable AVN800XC by Herrenknecht excavated 230 meters of tunnel a gradient of 17 degrees until it hit stable rock at a depth of 120 meters. With the cutterhead folded, the machine could be pulled back through the duct. The starting signal sounded for the HDD rig.
