Kerb and channel policy reviewed

Auckland City Council’s Transport Committee yesterday reviewed its kerb and channel policy, and specifically, the financial and visual issues concerning the use of basalt ‘bluestone’ kerbs.

Auckland City owns 2,243 km of kerb and channel across the city, of which 1 to 2 per cent is renewed each year.

Two types of material constitute the city’s kerbs: basalt ‘bluestone’ representing 47 per cent of the total city’s kerbs concrete options, both block and extruded concrete, representing 53 per cent.

Both types of kerb are used in conjunction with concrete channel. However, the ‘bluestone’ is in short supply, needs to be imported from other New Zealand districts, and is more expensive to lay and maintain. Basalt ‘bluestone’ does not perform as well as the concrete option: over time, the joints crack allowing water to escalate into the ground. Basalt ‘bluestone’ kerbs are not kind to wheel rims and tyres. The comparative costs are:

New basalt ‘bluestone’ $180/m Recycling existing basalt ‘bluestone’ $100/m New pre-cast concrete $65/m Extruded concrete $55/m

“While concrete seems to be the best option from a stormwater drainage point of view, we’ve recognised that many people prefer ‘bluestone’ for its high heritage and aesthetic value,” said Councillor Greg McKeown, Transport Committee chairperson. “As we have done earlier in the year for footpaths, it is important to maintain some uniformity within an area with regard to choice of materials, and the new policy attempts to address that by improving the recycling of existing stones and retaining them, subject to supply, in special interest areas across the whole city.

“However, we must also look to improve the drainage performance of kerb and channel and reduce the overall maintenance costs where sensible. By using concrete on more arterial and strategic roads, we will improve performance, lower maintenance costs, and under this new policy, save up to $56,000 per year.”

Kerb and channel forms a road drainage system preventing surface water from entering and weakening the road pavement. It ultimately helps prevent flooding, minimise hazards to motorists and reduce maintenance works.

Community boards will be advised of the reviewed policy. The renewal cost, advantages and disadvantages of each material will be presented to the public.

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