PREMATURE FAILURE of chamber and gully structures in roads is a common problem, costing £200M a year. The Highways Agency hopes to reduce this by 20% with the launch in August of the Design Manual for Roads & Bridges which includes a new advice note on installing and maintaining chamber and gully tops.
A research programme at Nottingham University saw consultation with highways and utility suppliers with private sector product development carrying on alongside.
One firm to develop a solution is RMC, which recently launched the ReadyRaise system. The product combines precast concrete components with resin based compounds.
'Early failure of road ironworks support structures presents a big problem for utilities and highway authorities, which contract out street works services and ultimately foot the construction and maintenance bill, ' says RMC Surfacing's marketing manager Richard Jenman.
The company found that a common problem was the interaction between traditional rigid ironwork support structures and the surrounding flexible pavement.
'The brickwork and bedding mortar of chamber tops has tended to collapse under horizontal loading transferred from the ironwork and pavement, ' says Jenman. 'There is also particular risk of failure when the chamber cover is exposed in the event of road surface planing during highway maintenance projects.'
ReadyRaise uses a bedding compound to seat the unit on the chamber cover slab or a sound brickwork shaft and to bed the ironwork within the collar.
The ironwork is surrounded by a locking compound, which absorbs horizontal movement and forces.
According to Jenman, this material can also be used as a wearing course, allowing the road to be opened within hours of installation.
The Highways Agency estimates 20% will be shaved off the annual repair bill if contractors and authorities follow the new guidance.