The typical method of preventing corrosion inside the steel upper box girder in a
suspension bridge involves the use of synthetic paints. However, in an effort to reduce
environmental impact and cost, the suspension portion of the Yeongjong Bridge utilizes
dehumidification systems to control humidity and prevent corrosion inside its box girder.
Maintaining a uniform humidity distribution at the proper level inside the box girder is critical to
the successful prevention of corrosion. In this study, the humidity and the resultant corrosivity
inside the box girder of the Yeongjong Bridge was monitored. The corrosion rate of the steel
inside the box girder was obtained using thin-film electrical resistance (TFER) corrosion
sensors. Time-of-wetness (TOW) measurements and the deposition rates of atmospheric
pollutants (e.g. Cl- and SOx) were also obtained. Classification of the atmospheric corrosivity
inside the box girder was evaluated per ISO 9223. No corrosion was found in the upper box
girder, indicating that the dehumidification system used in the Yeongjong Bridge is an effective
corrosion control method.