Challenge

Derby City Council ‘Connecting Derby’ transport improvement scheme required the cost effective integration of the surface water management system serving both new and refurbished highways created to complete the city’s inner ring road.

This would increase the flow, not the volume, of vehicles around the city, completing the inner ring road, first started in the 1970s.

Brief:

1. Be optimised to the requirements of all users and forms of transportation.
2. Minimise the extent of new in-carriageway and below ground infrastructure.
3. Minimise the cost of installation and ongoing maintenance.

The major challenge facing the drainage designers was to find the most efficient and cost effective way of tying new connections into the existing sewers and discharge watercourses.

Solution

Two KerbDrain sizes have been installed: the highest capacity KerbDrain 480 and the mid capacity KerbDrain 305. All the units have a half-battered profile, are 500mm in length and are sealed during installation to prevent any infiltration into the surrounding sub-soil. The range of accessories used include drop kerbs with perforated flush centre stones, 90 degree quadrants, bus stop kerbs, external radius sets, access units and gullies.

Outcome

The scheme, totalling £36m, considered the interests vehicles, cyclists, buses and pedestrians, improving access by upgrading the links to and the environment around the city’s main arterial highway junctions. In total, close to 1.5km of new road has been built with a further 1.5km of online improvements made to the existing routes.

“Using point gullies would have been prohibitively expensive, both in terms of initial capital cost and in their ongoing maintenance, as large numbers would have been required to meet the hydraulic performance needed,” says Murray Parker, Project Engineer at Derby City Council. “We had used ACO KerbDrain on other urban projects and found it to be the ideal solution as it minimises the impact on below ground services – a significant benefit at complex junctions – is easy to install and has a wide range of accessories that enable us to create a seamless, high performance system that incorporates bus stops, roundabouts, pedestrian crossings, etc.”

“As outlet connections to existing sewers can be made at any point along a KerbDrain run we were able to fully value-engineer the design – a process that has eliminated the need to install any additional carrier pipework. The use of an environmentally sustainable material in its construction also made a significant contribution to the project achieving a very high ‘Considerate Constructors’ rating of 36 out of 40.”