South East England
Norwich City Council
The Norwich NDR is the largest privatised road project outside of the local authority remit in the UK and comprises 19.6km of dual carriageway, including nine new roundabouts, seven new bridges and an underpass. The new road aims to improve traffic flow on the northern section of Norwich’s outer ring road and provide the required infrastructure to allow for planned growth within the city.
A tailored surface water drainage system was required for the project to ensure that surface water from the new road would be captured before it could form a pool and then be carried through a number of drainage runs into the existing sewer network.
Polypipe worked closely with main contractor, Balfour Beatty during 2016 and 2017 to design and manufacture a tailored solution. The final design took advantage of the high-quality value engineering available with Polypipe’s Ridgistorm-XL and Ridgidrain systems.
Polypipe’s Ridgidrain system was supplied to manage the surface water gathered on the road, with the product specified in diameters ranging from 225-600mm. The Ridgidrain system is the first twinwall surface drainage system in the UK with Highways Authority Product Approval Scheme (HAPAS) status. Over 350 catchpits with 100 and 150mm inlet / outlets were also installed and then connected to Polypipe’s Linflex Type 8.
Polypipe also supplied 384m of Ridgistorm-XL large diameter plastic pipework in 750mm diameter, which was installed beneath the central reservation on the main carriageway.
The pipework was manufactured to the ideal stiffness specification to handle the ground conditions on site and provided considerable installation savings, by minimising the volume of imported granular fill needed for other types of pipes. This system deals efficiently with the conveyance and attenuation of storm water on the road’s new surface.
Installation was quick and easy and the site functioned as a road to the general public throughout the construction. Due to the light-in-weight nature of plastic and the ability of Polypipe to design and deliver products direct to site at the precise time they were required, the solution ensured efficient installation. Polypipe was able to deliver these benefits thanks to its plastic systems, which were provided as an alternative to the initially specified concrete.