U-Station Rennweg, Nürnberg

Beneath the streets of Nuremberg, a technical renovation has become an architectural statement: the Rennweg subway station has regained its connection to the surface.

Light & Fresh Air for Nuremberg’s Underground

Beneath Nuremberg’s streets, a technical renovation has become an architectural statement: The Rennweg subway station has regained its connection to the surface. New glass domes not only bring light and fresh air into the underground, but also combine safety, functionality, and design. A project that demonstrates how modern urban planning makes underground spaces more livable.

Project

Lichtkuppelsanierung im laufenden U-Bahn-Betrieb

Location

Nürnberg

Client

Stadt Nürnberg

Execution

INDU LIGHT

Products used

INDU LIGHT sets accents

Glasline Post-and-Beam System

The flexible post-and-beam glass roof system with slim profiles, customizable glazing, and integrated ventilation, smoke and heat exhaust, and shading systems.

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The old skylights were suffering from material fatigue and posed a safety hazard to pedestrians.

Beneath the surface of modern cities lies a world of its own—built of concrete and steel. When you step into a subway station, you leave daylight behind. You descend, leave familiar landmarks behind, and often lose your sense of time and space.

Daylight—or the lack thereof—in particular shapes the atmosphere of these places. Where there is no light, a feeling of confinement, disorientation, and anonymity arises. This feeling is often reinforced by the stagnant air and the generally oppressive atmosphere. This makes architectural elements that bring light and fresh air underground and establish a visual connection to the outside world all the more significant.

One example of how this connection can be achieved is the Rennweg subway station in Nuremberg, which, since its opening in May 1993, has created a deliberate connection between the platform level and the street space through its striking skylights. The walls and ceiling are adorned with colorful graffiti by Nuremberg artists.

Architecture, functionality, and durability in harmony

More than 30 years after the station opened, the polycarbonate skylights originally installed had begun to show signs of material fatigue. They had become brittle, barely let any daylight inside, and posed a significant safety risk. This is because the skylights are located above the subway station, at street level for pedestrians in the middle of a pedestrian zone. In the meantime, they had to be secured all around with construction fences to prevent them from falling or collapsing.

In addition to the safety-related deficiencies, a fire safety assessment revealed the need to integrate smoke vents into at least two of the seven skylights to ensure safe smoke extraction from the platform level in an emergency.

These functional requirements, combined with the design requirements for a harmonious streetscape, led to a fundamental redesign. All seven skylights were equipped with appropriate louvered ventilators and integrated weather protection grilles. This enables continuous air exchange. “The decision to bring all skylights to a uniform level was, in our view, absolutely the right one—not only technically, but also in terms of design,” said Rüdiger Schultze of the City of Nuremberg’s Subway Construction Office.

The switch to a modern glass solution was also a deliberate choice—for safety, lighting, and design reasons. “Glass—simply because of the brightness. Natural light in the subway station—that was no longer the case with the old domes; nothing got through anymore,” reports Schultze. In addition to improving daylight yield, the new design also significantly ensured the safety and durability of the skylights.

The Glasline system from INDU LIGHT was used to realize the free-form roof design. The narrow frame profile offers high flexibility in architectural design and thus ideally meets the client’s requirements.

The seven skylights were replaced with a modern glass system featuring an integrated ventilation function.

Technical implementation during ongoing subway operations

A particular challenge was carrying out the construction work while the subway line remained in operation and within a bustling residential area. The station is located in a traffic-calmed zone with heavy pedestrian and bicycle traffic, surrounded by residential buildings. To meet the needs of the Greater Nuremberg Transport Association (VGN) and the residents around Rennweg, a rigorous just-in-time concept was implemented and combined with a high degree of factory prefabrication.

The new glass domes consist of walk-on safety glazing in accordance with DIN 18008-6 and an octagonal steel substructure with a diameter of 3.7 m. To keep on-site installation work to a minimum, the skylights were pre-assembled by INDU LIGHT and delivered to Nuremberg via three overnight heavy-haul transports. Each transport was handled individually and closely coordinated with the immediately following installation to precisely adhere to space constraints, time windows, and safety requirements.

“Our installers had to be on site around 5 a.m. to handle the delivery, because the heavy-haul transport had to be completed by 6 a.m. and out of the city limits,” says INDU LIGHT project manager Simon Gervers, describing the logistical challenge. This is because road closures had to be arranged and special permits obtained to bring the semi-trailer into the traffic-calmed section of Rennweg. “The challenge was to reopen the road to traffic as quickly as possible without causing a lot of noise, so as not to disturb the residents,” Gervers continues.

The collaboration with INDU LIGHT was viewed by all involved as a truly collaborative partnership: “It was truly a very human collaboration—from communication through to implementation,” said Rüdiger Schultze of the City of Nuremberg’s Subway Construction Office. The use of the Glasline system not only significantly enhanced functionality and safety but also set a design benchmark for modern subway architecture—bright, open, and precisely tailored.

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