A NEW technique to combat corrosion in suspension bridge cables to rival dehumidification won the Vinci Innovation Awards Grand Prize last month The technique, known as the Cohestrands system, involves enclosing bundles of seven wires in a continuous polyethylene sheath which prevents water ingress.
Suspension cable corrosion is caused by water trapped during cable spinning or by water entering through cracks in paintwork.
Since the Cohestrands system is manufactured under factory conditions, it is claimed moisture cannot enter during cable spinning.
The system was invented by cable specialist Freyssinet.
Company technical director Benoît Lecinq said that it was the only product on the market to rival dehumidification.
Dehumidification is used on modern suspension bridges where dry air is pumped through cables to remove moisture. It is being considered as a way of tackling corrosion on the UK's Forth Road Bridge (see feature page 9).
Freyssinet has tested Cohestrand for moisture ingress and robustness in the field and under laboratory conditions.
Last summer it supplied cables for the first Cohestrand structure - the Kanne Road Bridge in Belgium. The cables will be checked in summer 2006 for water ingress.