Crucial load test marks new phase for Łódź rail tunnel

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A successful heavy-load test of a giant gantry crane on the western edge of Łódź has marked a crucial milestone for the high-speed rail tunnel that will run beneath the city, signaling that excavation of what is set to become Poland’s longest railway tunnel is edging closer to reality.

Heavy-load trial proves key machinery is ready

The recent test at the Retkinia construction site focused on the massive gantry crane that will handle the heaviest components of the tunnel boring machine, or TBM. According to publicly available information, engineers verified the crane’s performance by lifting water-filled ballast bags weighing around 500 tonnes, exceeding the crane’s nominal lifting capacity.

Reports indicate that the crane is rated for approximately 450 tonnes, but project managers opted to test it at about 110 percent of that limit to confirm it can safely manage the most demanding operations ahead. The main task will be lifting the TBM’s cutterhead, which alone is expected to weigh in the region of 420 tonnes, and lowering it into the launch chamber in a single, carefully controlled move.

Local infrastructure coverage describes the test as a pivotal safety check before assembly of the TBM begins on site. With the gantry crane now cleared for use, the project can move from preparatory civil works toward the complex mechanical phase that will ultimately allow continuous tunneling beneath Łódź.

Observers of the scheme note that this type of load test is standard practice on major underground projects, but its timing in late June 2026 gives it outsized significance. It effectively marks the transition from building the supporting structures for the tunnel to preparing the machinery that will bore the main high-speed rail tube.

Poland’s future longest rail tunnel takes shape

The high-speed rail tunnel under Łódź forms part of a broader network intended to connect Poland’s planned central transport hub with major cities such as Warsaw, Wrocław and Poznań. Public information from the project promoter and contractors describes a single-bore tunnel roughly 4.6 kilometers long, with an internal diameter of about 14 meters, making it one of the largest rail tunnels attempted in the country.

Once complete, the tunnel is expected to carry long-distance and high-speed trains beneath the dense urban fabric of Łódź at depths of up to around 30 to 35 meters. The alignment links a launch shaft in Retkinia to the vicinity of the existing Łódź Fabryczna station, creating an underground east–west rail corridor that avoids surface-level conflicts with city streets and buildings.

According to recent Polish trade press coverage, the project is designed to complement the separate cross-city tunnel for regional services, creating a layered rail system underneath Łódź. Together, the schemes are intended to reduce travel times across central Poland while relieving congestion on legacy lines that currently skirt or cross the city at grade.

Specialist engineering material describing the tunnel points to demanding ground conditions and the tightly built-up environment as key challenges. The large-diameter TBM will have to pass under existing structures with strict settlement limits, and the interior of the tunnel will later be equipped with advanced signalling and safety systems tailored to high-speed operations.

From TBM delivery to full-scale excavation

Preparations for actual tunneling have been building for months. Reports published earlier in 2026 noted that the first elements of the TBM, including sections of the cutterhead, began arriving at the Łódź construction site during the winter. These components are now due to be assembled in the Retkinia launch chamber, with the gantry crane playing a central role.

The assembly phase will involve lifting and positioning multiple heavy segments of the TBM, ranging from the front shield to the trailing support gantries. Once the machine is fully built and tested in the shaft, project documentation indicates that it will begin its drive toward the city center, installing precast concrete segments to line the tunnel as it advances.

According to Polish infrastructure media, the tunnel is being bored at a “safe depth” intended to minimize disruption at the surface. This approach mirrors practices on other European urban rail tunnels, where deeper alignments can reduce the risk of ground movement under sensitive historic districts, at the cost of more complex access and ventilation requirements.

While no precise start date for full-scale TBM operation has been publicly confirmed, the successful crane test suggests that the project is entering a more visible phase. Residents can expect an uptick in logistics activity around the launch site as additional TBM components, tunnel lining segments and support equipment are delivered and assembled.

Timelines, testing and passenger impact

Planning material and recent news coverage indicate that structural excavation of the tunnel is only one part of a multi-year program. After the TBM completes its drive under Łódź, contractors will still need to install track, power supply, signalling, ventilation and fire safety systems along the entire length of the bore.

Reports from Polish infrastructure outlets suggest that finishing works and safety testing are expected to continue into the latter part of this decade, with technical approvals and acceptance procedures currently projected around the turn of the 2020s and 2030s. These tests are likely to include trial operations with empty and then passenger trains, evacuation exercises and full verification of the tunnel’s emergency systems.

For passengers, the long-term impact is expected to be substantial. By routing high-speed and long-distance services directly under Łódź, journey times between central Poland and key regional cities could be significantly reduced, while the future integration of high-speed and regional tunnels may turn Łódź Fabryczna into a more prominent interchange point on the national rail map.

In the short term, the project continues to bring construction traffic, road adjustments and visual changes to areas around the launch and reception sites. Publicly available updates emphasize that managing these temporary disruptions is a key part of maintaining support for a scheme whose benefits will only become fully visible in the next decade.

A crucial test in a city defined by rail megaprojects

Łódź has in recent years become a focal point for rail construction in Poland, with the cross-city tunnel for regional trains and the high-speed tunnel both reshaping the urban underground. The successful heavy-load test on the Retkinia gantry crane underlines how much of this transformation depends on relatively unspectacular but technically demanding checks completed far from public view.

Specialist reporting on the city’s rail projects notes that the high-speed tunnel must be delivered in parallel with complex works on the existing cross-city line, where separate contracts for an earlier tunnel have faced challenges and contractual changes. That context adds extra weight to each technical milestone reached on the new high-speed bore.

For engineers, the crane test serves as a controlled rehearsal of the high-stakes lifts to come, when the TBM’s most valuable components are moved into position above the launch chamber. For planners and passengers watching the project from the surface, it is a visible sign that Poland’s most ambitious urban rail tunnel is moving from drawings and excavation pits toward the moment when the first cutterhead begins its journey under Łódź.

As summer 2026 progresses, further updates are expected on TBM assembly, tunnel drive parameters and the sequence of works that will follow. Each of these steps will help determine whether the ambitious schedule for the Łódź high-speed rail tunnel can be maintained, and how soon travelers will feel the benefits of faster, more direct rail links beneath the city.