Bridge Dehumidification Services

In today’s interconnected world, bridges play a critical role in enabling mobility, economic activity, and social cohesion. Far beyond their structural function, bridges are indispensable assets in national and regional infrastructure, acting as key connectors between cities, islands, and entire countries. Whether carrying heavy traffic over rivers, fjords, or busy harbors, they help move people, goods, and services reliably and efficiently. Many of these structures also serve as cultural landmarks and technological achievements—symbols of progress and cooperation. As such, ensuring their long-term performance and integrity is both an engineering obligation and a societal investment.

Bridges, especially large suspension structures, face significant environmental challenges due to exposure to humidity, salt, wind, and mechanical stress. Maintenance of such complex structures requires a deep understanding of both materials and environmental conditions. Without proactive measures, especially in enclosed steel elements, corrosion can develop and cause long-term structural damage. Belvent A/S has worked at the forefront of bridge preservation for decades, delivering customized solutions that protect these critical structures while extending their useful life.

Belvent A/S – Expertise in Bridge Preservation

Belvent A/S has been a trusted partner in bridge maintenance since the early 2000s and has played a key role in shaping many of the industry’s best practices. With a heritage dating back to 1966, the company combines technical excellence with deep industry insight. Over the years, Belvent has developed and delivered dehumidification systems for some of the most advanced and exposed bridges in the world, helping preserve critical infrastructure while reducing maintenance costs.

Our expertise spans the dehumidification of closed steel chambers, main cables, anchorages, tower saddles, and box girders. We offer end-to-end solutions from consulting and feasibility studies to design, manufacturing, installation, and ongoing support. Every system is tailored to the unique characteristics of the bridge in question. Through innovative design and SCADA-based monitoring, we provide full oversight and proactive protection—ensuring reliability and safety for generations.

How Bridge Dehumidification Works

Belvent's dehumidification systems operate by extracting moist air from closed bridge components and maintaining the internal environment below 40–50% relative humidity. This is a critical threshold, as corrosion of steel is virtually halted below this level. The dry air is distributed through a system of ducts and sleeves, ensuring that every relevant part of the bridge—such as main cables, anchor houses, steel boxes, and towers—receives proper airflow and remains protected.

Air is injected into sealed structures using specially developed sleeves that allow for internal circulation. In cable dehumidification systems, air enters and exits the main cables through breathable sleeves without compromising the cable’s structural integrity. The systems are controlled via SCADA platforms, which provide real-time data on humidity, temperature, and airflow, while also enabling remote adjustments and alarms. This level of control ensures long-term reliability and reduces the need for manual inspections.

Advantages of Bridge Dehumidification

Dehumidification offers a highly effective and low-cost method of preserving steel structures compared to traditional corrosion protection techniques. Instead of relying solely on coatings, wraps, or periodic repainting, a well-designed dehumidification system maintains optimal internal conditions at all times—drastically extending the life of critical components. Studies show that total lifecycle costs can be significantly reduced, as downtime and structural repairs are minimized.

In addition, the systems are energy-efficient, require limited maintenance, and offer long operational life spans. The ability to monitor and control conditions continuously reduces the risk of unexpected failures and helps infrastructure owners meet increasingly strict safety and sustainability standards. For large and complex bridges, dehumidification is often the only viable long-term protection strategy for inaccessible or sealed components.

Belvent’s Services

Belvent provides full-scope solutions for bridge dehumidification, combining engineering expertise with hands-on project execution. We begin with feasibility studies, site inspections, and flow simulations to assess system requirements. Based on these insights, we develop tailored designs that ensure effective air distribution, efficient system layout, and easy maintenance access.

During the execution phase, we fabricate and install custom ductwork, injection sleeves, extraction points, and dehumidifiers. All systems are rigorously tested before handover. Our offering includes mock-up installations, performance validation, and integration with SCADA systems. Post-installation, Belvent offers long-term service agreements, periodic maintenance, and system optimization to ensure the best possible performance. Spare parts, remote diagnostics, and software updates are also available as part of our long-term support commitment.

International Experience & Landmark Projects

Belvent has delivered bridge dehumidification systems to many of Europe’s and the world’s most iconic suspension bridges. Our portfolio includes the Great Belt Bridge (Denmark), Högakustenbron (Sweden), Bosphorus I & II (Turkey), and major suspension bridges in Norway. These projects span decades and reflect our ability to deliver reliable, scalable solutions for complex and exposed environments.

Our history also includes pioneering work on the Lillebælt Bridge—recognized as the first bridge outside of Japan to implement dehumidification on its main cables and the first globally to apply the method to a steel box girder. While not installed by Belvent in that case, the project helped lay the groundwork for our current role as one of the field’s leading technical partners. Today, Belvent is among the most experienced and respected suppliers of dehumidification systems in the global bridge industry.

In-House Capacity & Technical Strength

To support our project delivery, Belvent maintains a large in-house production facility equipped with state-of-the-art machinery for fabrication, testing, and prototyping. We handle everything from laser cutting and bending to welding, painting, and component assembly—giving us full control over quality, lead times, and adaptability to project-specific needs.

Our deep experience with industrial and process ventilation strengthens our ability to handle technically demanding projects with strict requirements for airflow, filtration, temperature control, and energy efficiency. Combined with our SCADA capabilities, we offer clients complete, integrated systems that go beyond standard solutions and contribute to long-term structural resilience.