TBM cradle completed as preparations for installation reach a key milestone

Work is progressing in Łódź to prepare 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 being progressively assembled into a single structure.

A key element of the preparations was the completion of the so-called cradle, a specially shaped, semi-circular concrete foundation that supports the TBM shield casing. This structure 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 with which the cradle has been constructed is particularly important for the start of tunnelling. Even minor geometric deviations could affect the machine’s trajectory during the initial phase of tunnel construction. The cradle therefore had to be built to a high degree of precision, with continuous technical supervision throughout the process.

An international team of specialists worked round the clock

Constructing the cradle was a demanding undertaking, both organisationally and technologically. The construction works took almost three weeks to complete, with work continuing around the clock, seven days a week.

The works were carried out by four specialised tunnelling teams comprising experts from several European countries, including Poland, Austria, Germany, Slovakia, Romania, Croatia and Italy.

Tunnelling scheduled to begin in the first quarter of 2027

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 developed by the tunnel’s general contractor, PORR S.A., tunnelling is set to begin in the first quarter of 2027.

“The use of TBM technology will enable construction work to be carried out beneath the city while minimising the impact on existing buildings and urban infrastructure. This method is now standard practice for major tunnelling projects in densely urbanised areas, providing a high level of safety and precision”, says Mateusz Kura, Project Manager at the Łódź-Sieradz Portfolio Office, Port Polska.

Work is also progressing on the intermediate chambers

Progress is also being made on other sections of the project. Construction of the intermediate chambers is under way, and once completed, they will be used for ventilation and evacuation purposes.

The K5 intermediate chamber, located near Atlas Arena on Al. Bandurskiego, is currently at the preparatory works stage. At Nad Karolewką Street, meanwhile, the main construction phase of the K6 chamber has begun, including the construction of the excavation support using diaphragm wall technology.