M4 Gets Smart with Polypipe Top Hats

By Admin

Polypipe Civils

4th Dec 2019

Polypipe’s Ridgidrain pipe and ‘top hat’ connectors deliver speed and cost benefits to drainage works on the M4 smart motorway.

Taylor Woodrow has installed over 3200m of Ridgidrain and 1000 ‘top hat’ chamber base connectors from Polypipe Civils & Infrastructure, the UK’s leading manufacturer of sustainable drainage and water management solutions, as part of its M4 smart motorway works. The flexibility of the Ridgidrain system led to savings on installation time and materials when compared to other options.

“The versatility of Ridgidrain when delivered on-site helps our teams to make maximum use of the materials at their disposal,” says Taylor Woodrow engineer Guy Miller. “Ridgidrain allows for pipe sections to be cut to length to meet the onsite requirements without affecting pipe integrity or the ability to link it with the other components of the motorway’s surface water management system. This saves time and provides us with the assurance that the installed system will stand the test of time.”

Speed of installation is an important factor, as one of Highways England’s highest priorities is to minimise disruption to traffic and communities during works. Polypipe’s ability to supply the required amount of Ridgidrain within a tight timeframe also influenced Balfour Beatty Vinci JV decision to use the system for the central reservation drainage.

Highways England will invest £848m in total to create the new smart section of the M4 between Hayes and Theale, the longest in the UK. A joint venture between Balfour Beatty and VINCI subsidiaries VINCI Grands Projets and Taylor Woodrow is delivering a package of smart motorway upgrades which includes the M4 between junctions 3 and 12. The works, which involves widening the motorway from three to four lanes, rebuilding 13 major structures and deploying active traffic management (ATM) technologies, are designed to increase traffic capacity – currently running at 130,000 vehicles per day – on the capital’s transport critical primary western route

Balfour Beatty VINCI JV started work on the two-mile section of the M4 between junctions 8 and 12 in October 2018. Upgrading the drainage is an important part of the works, as rainfall continues to increase all year round.

Ridgidrain pipe is a versatile non-pressure surface water and subsurface water structured-wall carrier drain system. Manufactured to nominal stiffness SN6, its high crush resistance and strength-to-weight ratio makes it ideal for stormwater applications where high traffic loads are expected. Integral sockets for easy pipe alignment make installation rapid and straightforward.

With plain-ended pipes available in diameters ranging from 100 to 600mm, and internally-socketed versions from 400 to 900mm, Ridgidrain is the first twinwall surface water drainage system with Highways Authority Product Approval Scheme (HAPAS) up to diameters of 900mm

Connecting the plastic subsurface network with concrete drainage elements on the surface of the motorway, the bespoke flange ‘top hat’ chamber base connectors act as inlets and conduits for the slip-formed concrete slot drains sited along the central reservation. They get their millinery nickname from their appearance when slotted over the end of Ridgidrain pipe.

John Moss, Business Development Director, Polypipe Civils, adds: “Polypipe offered Taylor Woodrow a better economy of scale than other available systems for this project. The value proposition from Polypipe was strong as we helped to optimise the efficient use of materials on-site, proving to be more versatile and adaptable to the ground conditions and section length requirements. This adaptability includes plastic’s ability to flex with ground movements, eliminating the need for rocker and stub pipes when entering and coming out of chambers, as would be required with traditional materials”.

Polypipe is also providing a combination of Ridgidrain and manufactured top hat connectors with bespoke flange connections for the next phase of the project which involves installing surface water drainage along the grass verges flanking the carriageways. The M4 smart motorway works are due to finish in 2022.

For more information about Polypipe Civils & Infrastructure full range of water management solutions, please visit or call: 01509 615100.

Tags on this post: drainage