The Dunedin City Council should be more open with the public regarding its trial of chemical de-icing agent calcium magnesium acetate (CMA) on city roads, an Automobile Association Otago district councillor Lyn McKie says.
CMA had been trialled by the council on certain roads since 2006 but little was known about its effectiveness, Mrs McKie said.
While people living near areas being treated with CMA were aware of the trial, many motorists were unaware it could be slippery when first applied.
"While the council are being proactive in using CMA, they should be more communicative about it," she said.
Dunedin City Council roading and maintenance engineer Peter Standring confirmed on Tuesday that CMA had been sprayed on Three Mile Hill Rd at 11.30am.
The road was the site of a serious accident at 4.35pm.
CMA could be slippery "like water" when first applied and the council would consider setting up road signs warning motorists to slow down near treated areas, Mr Standring said.
The trial of CMA, which was expected to be completed in the next couple of years, showed the product was more expensive than grit, which was sourced locally, but it had many advantages.
Grit entered mud tanks, caused damage to other vehicles and could be a hazard if not cleared from roads.
CMA could be sprayed on areas several days before predicted frosty conditions, whereas grit laying would be done that morning, he said.
It was a likely both CMA and grit would still be used after the trial ended.
What is CMA?
> CMA - calcium magnesium acetate - is a de-icing and anti-icing agent being tested on 15km of Dunedin roads - Three Mile Hill Rd, Taieri Rd, Fea St, Orbell St, Maclaggan St, Brockville Rd, Stuart St, Maori Rd and Glen Rd.
> CMA is less corrosive than tap water, is safe for children and pets, does not require protective gloves to handle and does not harm skin.
> It is environmentally safe with very low toxicity levels and is safe for vegetation
- Source: Dunedin City Council
