Island Roads will use an inflatable resin ‘balloon’ liner which is pulled through the structure, sealed at both ends and then inflated to fit the aperture. UV lighting is then used to cure the resin, providing a protective, hard-wearing liner which will strengthen and protect the original brickwork.
Because the brook is several metres below road level, a special temporary ramp will need to be constructed to get the necessary equipment and materials on and off site.
The inflated resin liner technique has previously been used by Island Roads to perform a similar function at several smaller bridge structures, including Holbrooke’s Bridge in Bouldnor – home to the award-winning ‘eelevator’ which assists migrating eels.
Ian Hodson, Island Roads structures manager, said: “This is a difficult work site given that it is a confined space and also several metres below the road level.
“But it is vital we stabilise and strengthen the culvert given the major disruption that would occur if it were allowed to deteriorate, or even collapse.
“The work we will be undertaking here is the last of four schemes across the Island this year, using an innovative and rapid solution which will allow us to extend the life of the structures with the minimum disruption.”
The work has to be carried out in the summer months when the water course levels are expected to be low, but has been programmed for completion before the main school summer holidays.
Work will begin on Monday (15 July) when the temporary ramp structure will be created. This will be done overnight between 6pm and 6.30am during which time there will be a road closure in place at the western end of Victoria Avenue, with traffic diverted via Lake, Apse Heath and Canteen Road.
The road will also be closed during the day from 9.30am to 9.30pm on Wednesday 17 July while the liner is installed. Again the diversion will be via Lake and Canteen Road.
Then on Thursday 18 July the road will again be closed overnight (6pm to 6.30am) to allow the equipment to be removed from site. It will also be necessary to control traffic via temporary traffic lights throughout the work programme.
Ian said: “We apologise for any inconvenience but we are working overnight where possible on a scheme that is necessary to improve what is an important – if largely unseen – part of the Island’s infrastructure.”