A new engineering method that prevents corrosion by regularly injecting dry air into steel bridge cables has been successfully tested on one of the world’s largest suspension bridges.
The innovative system, developed over the last five years by C. Spencer Ltd., a UK engineering firm, has thus far prevented corrosion of 11,000 tons of steel wire that make up the main cables on the Humber Bridge, which spans 2,220 meters (about 1.37 miles) across the Humber Estuary, a North Sea inlet on the East Coast of England.
The process, called main cable dehumidification, involves sealing the cables to create an air-tight environment and installing a system to produce and inject dehumidified air to dry the main cable wires, avoiding rust.
The dry air collects moisture along the way and expels it through a series of exhaust points installed along the cables. The installed equipment is permanent, and the cycle repeats continuously, drying out the15,000 wires that make up each cable, according to the Humber Bridge Board.
The system is monitored and controlled using an Internet-based system, which the board will control. Spencer will continue to monitor the cables for the next two years.
The Bridge Board and global engineering consultant AECOM are partners on the project.
Spencer has used the system on two other UK bridges. The technology has won several awards and could be exported globally within several years, officials say.
The project began in February and was to have been completed in December 2011, but it is running far ahead of schedule and is near completion.
Spencer used four specially designed gantries for the project, which allow crews to move along the main cables to carry out the sealing works and to install the injection and exhaust points.