The chamber is to be the entry point for the TBM that will bore the long-distance tunnel under Łódź. The project will unlock rail capacity through the currently terminal Łódź Fabryczna station and connect westward to Wrocław and Poznań, closing strategic gaps in Poland's rail infrastructure.
The Retkinia chamber is over 180 metres long – roughly the length of seven basketball courts or two football pitches – and 18–23 metres deep, with diaphragm walls reaching 43.5 metres. The -1 level will house technical systems, while level -2 will contain the track bed for Line 85. The internal staircases will ensure the smooth and prompt evacuation of the building in emergency situations.
Key construction data:
- Soil excavation: 84,376 m³
- Concrete: 29,924 m³ (structure + walls)
- Steel: ~3,000 tonnes
- Diaphragm walls: 436 linear metres, up to 43.52 m deep
- Max chamber depth: 23.36 m
At the project's peak, there were almost 100 workers on site, along with a full range of heavy machinery, including cranes, piling rigs and concrete mixers.
Excavation is scheduled to begin in Q4 2026, with HSR operations on the Warsaw– Łódź "Y-line" to follow in 2032.
Tunnel timeline and specifications
The CPK tunnel will be Poland's longest and widest single-bore railway tunnel: The bridge is 4.6 km long, 14 metres in diameter, and designed for two-way train traffic at speeds of up to 160 km/h. It is anticipated that Boring will commence no later than Q4 2026.
Tunnel depth will vary from 23 metres (at Retkinia) to 34 metres (near kilometre 3.2). The project will include five underground evacuation chambers, technical walkways, and full fire safety systems.
