Auckland Transport bites dust

Auckland Transport (AT) is trialling a range of methods to reduce dust from unsealed roads this month.

The $200,000 investigation will involve trialling five different dust suppression methods on Old Woodcocks Road in Kaipara Flats.

AT group manager of assets and maintenance Tony McCartney says the trial will provide a basis for future work to reduce dust from unsealed roads.

“We want to see what works and what doesn’t work, and of course we want to check out what method is the most cost effective,” Mr McCartney says.

“Dust is a problem on many roads, particularly in the north, and we want to work with the local community to try to get on top of the issue.”

Each treatment section will be 300 metres long and will be clearly marked to allow road users to provide feedback on the performance of each method.

The trial includes four sealed surfaces and an unsealed surface.

Two of the methods are for a conventional chip-seal – one on a cement/lime base, and the other using a chip-seal over the existing road base.

The other sealed treatment will be Otta Seal, which has been widely used as a cheaper alternative to conventional road sealing for low-volume roads. It creates a surface which stops dust and reduces potholes and corrugations, but uses much cheaper materials and very little preparation.

The fourth treatment is a new method developed by Downer called a dust seal emulsion binder, which involves spraying a bitumen emulsion onto an unsealed surface to bind the pavement.

The fifth trial method involves using a different kind of rock, known as MAP40, on the unsealed surface. The brown, weathered rock typically crushes under compaction, forming a tightly bound unsealed surface, which is expected to reduce dust.

There will also be an untreated section to act as a control.

An information brochure with a feedback slip will be provided to residents of Old Woodcocks Road, nearby schools and community facilities three months after the start of the trial and the Rodney Local Board will get an update on the trial every six months.