Bridge Humidity Control

Dehumidification with a DST Dehumidifier provides corrosion protection by reducing the amount of water that can potentially cause rust, resulting in a longer material lifespan, and the savings of resources. DST’s Dehumidifier technology has been implemented at the Sydney Harbour Bridge and the Auckland Bridge.

aerial view of bridge over body of water during daytime

Corrosion of mild steel components and high tensile support wires can quickly compromise structural integrity, resulting in safety issues, costly traffic restrictions, and potential bridge closure.

The girders, on which the tracks lay, can be protected against corrosion by the circulation of dry air through the truss, whereas corrosion protection paint is expensive and demands maintenance.

Painting the bridge increases the weight. Even affixed constructions can be dehumidified instead of using corrosion protection paint. A dehumidifier demands minimal maintenance and saves a lot of time compared to personnel applying corrosion protection paint. Corrosion protection is also necessary in spots very difficult to reach and dry air is often the preferred method.

Bridges (PDF)

FAQ

What is bridge dehumidification?

Bridge dehumidification is the process of removing excess moisture from the air surrounding and within bridge structures to prevent corrosion and deterioration. This is achieved using dehumidification systems that control the relative humidity (RH) levels, ensuring that they remain below the critical threshold where moisture can cause damage to the bridge materials.

How does humidity affect bridges?

Humidity can have several detrimental effects on bridges:

  • Corrosion: High humidity levels can lead to the rusting of steel components, weakening the structural integrity of the bridge.
  • Concrete Deterioration: Moisture can cause the expansion of concrete, leading to cracks and overall structural degradation.
  • Electrical and Mechanical Failures: In suspension bridges, for example, high humidity can affect the electrical and mechanical systems crucial for operation.
  • Safety Risks: Over time, unchecked humidity can compromise the bridge’s safety, leading to higher maintenance costs and potential hazards.

How does humidity control work?

Humidity control works by regulating the moisture content in the air to maintain a safe and optimal level of relative humidity. This is typically achieved through:

  • Dehumidifiers: Devices that extract moisture from the air, reducing the relative humidity to a predetermined level.
  • HVAC Systems: Heating, ventilation, and air conditioning systems that can include dehumidification functions.
  • Sensors and Controls: These monitor the humidity levels and adjust the dehumidification systems accordingly to maintain consistent conditions.

What technology is used to control humidity?

Various technologies are employed to control humidity, including:

  • Desiccant Dehumidifiers: These use materials that absorb moisture from the air, such as silica gel or lithium chloride.
  • Refrigerant Dehumidifiers: These cool the air to condense and remove moisture, then reheat the air to a comfortable temperature.
  • Humidity Sensors: Devices that measure the relative humidity in the environment and provide data to control systems.
  • Automated Control Systems: Integrated systems that use the data from sensors to adjust dehumidification equipment in real-time, ensuring optimal humidity levels are maintained.
  • Energy Recovery Systems: These reclaim energy from the dehumidification process to improve efficiency and reduce operational costs.

By utilizing these technologies, humidity control systems ensure that structures like bridges are protected from the damaging effects of moisture.