If no groundwater is present, we work in partial section with open shields, the most cost-effective variant of underground pipe jacking. This allows us to realize various tunnel profiles in the most diverse geologies and achieve high advance rates. Depending on the soil conditions, we work with excavator technology or with trenchers.
SONNTAG also uses manned shield tunneling where others resort to the significantly more complex microtunneling. Because we are able to carry out the partial section under compressed air. We use this technique, for example, when groundwater is present, but unpredictable obstacles make the use of microtunneling machines an economic risk.