Bridging Horizons: Arup’s ‘Pilen’ Viewpoint Offers a Portal into the Future of Infrastructure

In the coastal landscape of Rødbyhavn, Denmark, a striking piece of contemporary architecture has emerged, not as a permanent monument, but as a temporary witness to one of Europe’s most ambitious engineering feats. Named "Pilen"—Danish for "the arrow"—this demountable viewpoint was conceived by the global engineering and design firm Arup. Its purpose is twofold: to offer the public an intimate perspective on the monumental construction of the Fehmarnbelt Tunnel and to serve as an architectural symbol of connectivity between nations.

The Fehmarnbelt Tunnel: A Milestone in Engineering

The Fehmarnbelt Tunnel is currently under construction, an 18-kilometre-long immersed road-and-rail link destined to connect the Danish island of Lolland with the German island of Fehmarn. Once completed, this massive sub-sea structure will fundamentally reshape the transit map of Northern Europe. By replacing current ferry services with a direct, high-speed rail and motorway link, the tunnel will slash travel times between Hamburg and Copenhagen to just 2.5 hours, effectively bridging the gap between Scandinavia and the European continent.

The project involves the fabrication of 89 massive reinforced concrete elements, each weighing tens of thousands of tonnes, which are being produced in a specialized factory on the Danish side. These elements will be lowered into a dredged trench on the seabed, forming the longest immersed tunnel in the world.

Pilen: An Architectural Compass

Pilen is far more than a simple observation platform. Designed by Arup at the behest of Femern A/S, the company overseeing the tunnel’s construction, the structure acts as a physical manifestation of the project’s scale. The design is intentionally symbolic; its sharp, linear form mimics a compass needle, pointing directly toward the German coast where the tunnel will eventually emerge.

"The arrow-shaped design points towards the location where the Fehmarnbelt tunnel emerges on the German side, acting as a large compass needle for visitors," says Arup project architect Kristian Winther. This orientation helps users visualize the trajectory of the tunnel beneath the surface of the Baltic Sea, grounding the abstract scale of the project in the physical geography of the landscape.

Chronology of the Project

The development of Pilen is intrinsically linked to the broader construction timeline of the Fehmarnbelt link:

• Early Planning (2023–2024): Femern A/S identifies a need to foster public engagement and transparency regarding the massive scale of the construction site near Rødbyhavn. Arup is commissioned to design a temporary structure that allows safe public access to the area.
• Design and Engineering (2025): The design team focuses on sustainability and demountability. The decision is made to utilize modular, reusable components, emphasizing a circular construction philosophy.
• Construction and Opening (2026): Pilen is erected on the site, strategically placed to overlook the tunnel portal. It opens to the public, providing panoramic views of the coastal reclamation and the industrial assembly line for the tunnel elements.
• Operational Phase (2026–2029): The structure will remain in place throughout the duration of the tunnel construction, providing a rotating exhibition space and vantage point for visitors, local residents, and students.
• Decommissioning (2029): Following the projected completion of the tunnel, Pilen is scheduled to be carefully dismantled, with its components repurposed for future infrastructure projects.

Supporting Data and Design Specifications

The physical dimensions of Pilen are a direct nod to the technical reality of the tunnel project. The ramped structure measures exactly 217 metres in length—a precise reflection of the length of each individual concrete tunnel element.

• Structure: A hybrid of landfill timber and steel, chosen for both structural integrity and ease of disassembly.
• Height: The walkway rises 24 metres above sea level, providing an elevated vantage point that offers a bird’s-eye view of the expansive construction site.
• Accessibility: Designed as a fully accessible, landscaped zigzagging path, the structure ensures that the construction site can be viewed by all members of the public, regardless of physical ability.
• Sustainability: Every component, including the steel foundations, is engineered for "life beyond the viewpoint." By avoiding permanent concrete foundations, the site can be remediated to its original coastal state once the project concludes.

The Philosophy of "Design for Disassembly"

The decision to make Pilen a demountable structure is a hallmark of modern sustainable architecture. In the context of large-scale infrastructure projects, temporary facilities are often built with little regard for the life cycle of the materials used. Arup has inverted this norm.

"We hope the viewpoint will create a closer connection between the tunnel project, the local community, and visitors," says Winther. "Giving people an opportunity to experience the scale of the project more directly is key. But it was equally important that the viewpoint itself did not become an environmental burden."

By utilizing renewable materials like timber and modular steel connections, Arup ensures that when the tunnel opens to traffic in 2029, the site of the viewpoint can be returned to nature, or the materials can be diverted to new architectural applications, minimizing the project’s carbon footprint.

Implications for Public Engagement

Large-scale infrastructure projects, particularly those involving decades of construction and billions in investment, often face scrutiny from the public. By opening the construction site through initiatives like Pilen, Femern A/S is engaging in a sophisticated form of transparency.

The viewpoint allows the public to witness the "invisible" work of infrastructure. Often, the scale of such projects is impossible to grasp through press releases or digital renderings. By standing on the deck of Pilen, a visitor can see the scale of the concrete elements, the depth of the trench, and the shifting geography of the coastline.

Furthermore, this project aligns with a growing trend in landscape architecture and civil engineering to create "infrastructure-tourism." As seen with projects like the Titlis Tower in Switzerland or the Lech Mountain Mirror in Austria, well-designed viewpoints can transform industrial zones into cultural destinations, fostering a sense of civic pride and interest in engineering.

A Wider Context: The Changing Face of Denmark

The construction of the Fehmarnbelt Tunnel is accompanied by significant environmental and landscape interventions, including a 300,000-square-metre land reclamation scheme. This new land is being landscaped with artificial ponds, diverse vegetation, and native coastal plants, designed to offset the ecological impact of the tunnel construction.

Pilen serves as the perfect vantage point to observe this ecological transition. From the deck, visitors can see the contrast between the rigid, industrial nature of the tunnel elements and the soft, deliberate creation of the new nature reserves that will surround the tunnel entrance.

Conclusion: A Temporary Landmark with Lasting Impact

The Pilen viewpoint stands as a testament to the idea that utility and aesthetics can coexist, even in the heart of a major construction zone. It is a bridge between the public and the machine—a way to humanize the massive, subterranean, and seemingly cold nature of modern transport infrastructure.

As the Fehmarnbelt Tunnel progresses toward its 2029 deadline, Pilen will continue to provide a window into the future of European travel. When it is eventually dismantled, it will not leave behind a scar on the landscape, but rather a legacy of responsible, thoughtful engineering. It reminds us that while the tunnel may connect two physical shores, the process of its creation has successfully connected a community to its future. Through the simple geometry of an arrow, Arup has provided a perspective that will remain in the memories of visitors long after the steel and timber are gone.