COUNCILS COULD save £120M by repairing rather than replacing rusting lamp posts if a new strengthening technique lives up to its inventor's claims, lighting engineers said this week.
At least 200,000 of the country's estimated 750,000 seriously corroded columns could be fitted with a £200 external steel sleeve at a quarter of the cost of renewal, according to thesystem's mechanical engineer designer Roger Flude.
Institution of Lighting Engineers technical services manager David Coatham says the idea is 'promising', especially as it removes the inherent safety concerns of welding galvanised steel in the street.
'A survey of our members last year revealed more than 750,000 seriously corroded columns, but funding to replace only a tenth of them,' said Coatham. 'I estimate at least 500 a year will collapse if not quickly removed, and an economic, structurally sound repair could save a potential £120M over providing new columns.'
Most lamp posts fail through base corrosion at or just below ground level. The 1.4m high split sleeve is designed to externally reinforce this weakened zone. The gap between sleeve and post is filled with an alkaline cementitious grout designed to help neutralise the rusting steel.
'Base corrosion is caused by an acidic cocktail of road salts, acid rain and dog pee,' said Flude. 'Existing sleeve protection systems rely on complex insitu welding of galvanised steel resulting in unattractive and short-term protection.'
Flude claims the sleeve can extend upward to reinforce a second common area of rusting at the corners of the column's inspection door. And using a more innovative internal sleeve, inserted through this inspection door, it can reinforce internal rusting at the junction of column mast and base caused by rainwater penetration through leaking seals.