CPK Łódź HSR: Poland’s Rail Tunnel Advances, Future of High-Speed

CPK Advances Łódź High-Speed Rail Tunnel with Retkinia Chamber Completion

Poland’s ambitious Centralny Port Komunikacyjny (CPK) project has reached a significant milestone, heralding the imminent commencement of high-speed rail tunnel excavation in Łódź. The finalization of the Retkinia launching chamber marks a crucial step towards constructing the nation’s longest and widest single-bore railway tunnel, part of the broader Line 85 connecting Warsaw and Łódź. This development, announced on July 24, 2025, underscores CPK’s commitment to enhancing Poland’s transport infrastructure and represents a pivotal moment for the future of high-speed rail travel in the region. The Retkinia chamber is the launching point for the Tunnel Boring Machine (TBM) and sets the stage for the ambitious project to begin in the fourth quarter of 2026. The construction, managed by CPK, reflects a dedication to modernizing the rail infrastructure with an anticipated opening date of 2032 for the Warsaw-Łódź section.

Retkinia Chamber: Gateway to the Tunnel

The Retkinia launching chamber is a substantial undertaking in its own right. Stretching over 180 meters in length and reaching a depth of 23 meters, the chamber features diaphragm walls that extend to an impressive 43.5 meters. This structure encompasses two underground levels, with the first housing critical technical systems and the second dedicated to the track bed itself. The intricate design and construction of the Retkinia chamber highlight the complexities involved in large-scale underground infrastructure projects. “The development of sustainable and efficient transport requires modern solutions. That’s exactly what we’ve applied in building the Retkinia chamber – a key component of the HSR tunnel in Łódź,” said Piotr Rachwalski, CPK Board Member for Railway Investments.

Fabryczna Chamber: The TBM’s Destination

Simultaneously, construction is underway at the Fabryczna site, where the receiving chamber will serve as the TBM’s endpoint. Budimex is constructing this chamber with 150-centimeter-thick diaphragm walls surrounding a 22 by 30-meter area excavated to a depth of 26 meters. To ensure the structural integrity and separation of the high-speed tunnel from an adjacent Polskie Koleje Państwowe Polskie Linie Kolejowe (PKP PLK) tunnel, jet grouting techniques are being employed. This is an essential measure to prevent any potential interference between the two rail lines. Further supporting infrastructure, including additional concrete and steel structures, is currently being installed.

Stabilization and Reinforcement at the Łódź Cultural Centre

Alongside these primary chamber constructions, critical reinforcement works are progressing near the Łódź Cultural Centre. This historic structure required special attention to mitigate potential impacts from the tunnel excavation. Approximately 1,400 micropiles and jet grouting columns have been installed to stabilize the soil beneath the building. Steel bracing is now being added to the northern wing to further strengthen the structure. Areas that were previously dismantled are being rebuilt, demonstrating a commitment to preserving the cultural heritage while modernizing the transport infrastructure.

Tunnel Specifications and Operational Capabilities

The high-speed tunnel itself will be 4.6 kilometers long with a substantial 14-meter diameter, designed to accommodate trains traveling in both directions at speeds of up to 160 kilometers per hour. The depth of the tunnel will vary between 23 and 34 meters, ensuring sufficient clearance and structural integrity. It will incorporate five underground evacuation chambers, providing safe havens in the event of emergencies, and feature comprehensive technical walkways alongside state-of-the-art fire safety systems.

Protecting the Urban Landscape: Structural Assessments

CPK has engaged Albraco to conduct thorough structural assessments to safeguard buildings located along the tunnel route. These surveys focus on evaluating the safety and load-bearing capacity of structures within the urban environment. This proactive approach underlines CPK’s dedication to mitigating potential risks and ensuring the stability of existing buildings during and after construction. The implementation of these measures underscores a responsible approach to urban infrastructure development.

Conclusion

The completion of the Retkinia launching chamber signifies a crucial advancement for CPK’s high-speed rail project in Łódź, representing a significant step forward in the construction of Poland’s longest railway tunnel. With excavation slated to begin by late 2026, the project is rapidly transitioning from planning and preparation to on-site execution. The use of advanced construction techniques such as jet grouting and the integration of innovative structural designs for both launching and receiving chambers emphasize CPK’s commitment to modern rail infrastructure. The comprehensive safety measures, including structural assessments by Albraco and the incorporation of evacuation chambers and fire safety systems, highlight a focus on passenger safety and structural integrity. This project will further modernize the Polish transport network. The ambitious 480 km Y-line, designed to connect Warsaw, the future CPK airport, Łódź, Wrocław, and Poznań, is set to be completed by 2035. This extensive undertaking is poised to reshape Poland’s transportation landscape, supporting economic growth and improved connectivity across the nation.