Run-off system to help harbour

Gaps provide space for stormwater run-off. Photo / Brett Phibbs

A University of Auckland study has successfully tested a new road surface design that could help clean Auckland harbours.

The design has gaps between interconnected concrete paving that drain rainwater into stone-filled reservoirs, improving the quality of runoff that eventually flows into waterways.

Trials overseas found that the design concept worked.

Professor of civil and environmental engineering Elizabeth Fassman and masters student Samuel Blackbourn wanted to test the system under more difficult conditions and chose an inclined site with heavy traffic.

Dr Fassman was pleased at how well the two-year trial worked.

Stormwater runoff decreased by about 40 per cent compared with asphalt.

It also improved water quality entering the city's drains, reducing sediment, copper and zinc by 70 to 80 per cent.

Dr Fassman said less and cleaner stormwater was good for the environment.

Pollutants in Auckland's waterways threatened aquatic spawning grounds and created a toxic buildup in marine life.

The system also reduced stormwater, minimising stream erosion.

"It's a great solution. Anything we can do to make [the road] soak up rainwater is a good thing."

Dr Fassman said it was now up to policy-makers to use the research.

She would love to see future road construction adopt the permeable road design.

It suited most road conditions, including bus lanes and carparks.