Protecting structural steel from corrosion is challenging in the best of times, let alone difficult to access internal surfaces within a bridge structure. In 2020, WSP was tasked to consider options in relation to mitigating the risk of corrosion within such areas, which included the use of a dehumidification system, thus making the environment too dry for corrosion to occur. However, the ongoing high operational cost over the remaining life of the structure promoted WSP consider a different approach.
Using a multi-disciplinary approach, we developed a novel method to mitigate the risk of corrosion by maintaining the enclosed bridge’s internal air temperature and relative humidity above the level that condensation occurs on the steel surface. This variable dehumidification method is expected to not only minimise the risk of corrosion, but also provide overall cost savings of up to 73% over the next 40 years.
This webinar will present the science behind the novel variable dehumidification method, and a whole of life net present value cost analysis between the different options. It will also provide an overview of the proof of concept trials on a Welsh Rail Underbridge and on the Auckland Harbour Bridge, schematics of the dehumidification system, and the use of real time monitoring sensors to safely ascertain the efficacy of the developed method over the upcoming 12-month trial period.
Raed El Sarraf, Technical Principal – Asset Integrity Management, WSP in New Zealand
WSP Asset Management for Bridges
Auckland Harbour Bridge - Project