Precast concrete drainage products have enabled Highways England’s main project contractor Costain to safely deliver a new £192 million dual carriageway section of the A556 trunk road between the Cheshire towns of Knutsford in the south and Bowdon in the north. The dual carriageway enables this strategic route to bypass the villages of Tabley, Mere and Bucklow Hill. Over 50,000 vehicles a day use the 7km stretch of road, which is an important link between the M6 motorway at junction 19 and the M56 motorway at junction 7.
Costain’s design partner for the scheme was Capita. Along with the task of designing the new road, Capita was also responsible for developing a drainage design solution with the capacity to deal effectively with rainwater run-off from the new road.
The drainage design uses precast concrete surface water channels at the edge of the carriageways to convey rainwater run-off to a series of V-gratings and then into catchpits. Over 750 precast concrete catchpits have been used on this scheme in both 1200mm and 1800mm diameter. Manufactured by Concrete Pipeline Systems Association member FP McCann the precast concrete units incorporate a pre-cored monolithic base fitted with watertight, flexible connector seals to allow concrete drainage pipework to be connected quickly and easily to the unit.
The scheme also includes over 100 Easi-Base precast concrete manholes. Where the run-off cannot discharge directly manholes are used, many incorporating flow control units, penstocks and pollution control devices. These off-site manufactured solutions are quicker, easier and safer to install. As the system is manufactured under factory conditions and is quality assured, the units’ quality and finish are better than could have been achieved under site conditions. Users can be sure that the precast units comply with all necessary technical standards.
Simon Ellison, Costain’s sector director said: “These off-site manufactured precast concrete drainage chamber systems have helped us achieve our build programme and site safety targets. They are simple to install and the integrity of the finished units together with the cast-in openings and seals are integral to our long life, low maintenance drainage design for the A556 bypass”.