Polish HSL tunnel moves closer to construction
posted on 17th Aug 2026 11:31
Work on the high speed line tunnel project in Łódź is progressing. At the launch chamber in Retkinia, construction of the so-called cradle for the TBM shield has been completed, while assembly of the first components of the tunnel boring machine delivered to the construction site is under way. Excavation of one of the most important sections of underground railway infrastructure in Poland is scheduled to begin in 2027.
Intensive work is under way in Łódź to adapt the launch chamber for the installation of the automated Tunnel Boring Machine (TBM). The first components of the machine have already been lowered to the bottom of the chamber and are gradually being assembled into a single structure. A key part of the preparations was the completion of the so-called cradle: a specially shaped, semi-circular concrete foundation that supports the TBM shield. This element ensures that the machine is correctly positioned and enables it to be precisely guided into the launch opening prepared in the chamber wall.
The accuracy of the cradle is particularly important for the start of excavation. Even minor geometric deviations could affect the machine’s trajectory during the initial phase of tunnel construction. The structure therefore had to be built to a high degree of precision and under continuous technical supervision.
Constructing the cradle was a demanding undertaking, both organisationally and technologically. The work took almost three weeks and was carried out continuously, 24 hours a day, seven days a week. Four specialised tunnelling teams were responsible for constructing the structure, bringing together experts from several European countries, including Poland, Austria, Germany, Slovakia, Romania, Croatia and Italy.
Once assembly has been completed and the necessary technical tests have been carried out, the TBM will be guided into the prepared launch opening. According to the project schedule drawn up by the tunnel's general contractor, PORR S.A., excavation is scheduled to begin in the first quarter of 2027.
Progress is also visible on other sections of the project. Work is continuing on the construction of intermediate shafts, which will ultimately serve ventilation and emergency evacuation functions. The K5 intermediate shaft, located near Atlas Arena is currently at the preparatory works stage. Meanwhile, the main construction phase of the K6 shaft has begun, including the construction of excavation support using diaphragm wall technology.
