Vinegar keeps icy roads sweet

By MATHEW DEARNALEY transport reporter



Forget the salt, just pour on the vinegar for safer driving on icy highways this winter.

Transit New Zealand is hoping for fewer accidents and road closures on black spots in the southern Waikato and central North Island after winning an environmental tick for a chemical made up largely of dolomitic lime and vinegar.

Salt used to be spread on roads to melt ice, but was banned in the mid-1980s after lobbying by the Automobile Association and environmentalists. It was not only an environmental no-no, it corroded vehicles.

The more environmentally friendly lime and vinegar mixture, in a combination called calcium magnesium acetate (CMA), has been used in a five-year trial on parts of the DesertRoad.

It reduced skids and closures in the windy and shady Three Sisters area.

Now, Environment Waikato has sanctioned CMA for general use throughout its region, including icy stretches of highway such as the western bypass around Lake Taupo and the route over the Mamaku Range between Tirau and Rotorua.

Transit's resource consent does not cover the southern half of the Desert Road or approaches to Mt Ruapehu, which are Horizons Regional Council and Department of Conservation territory.

But both Transit and DoC are preparing to lodge consent applications with Palmerston North-based Horizons, hoping to use CMA during next year's winter months right up to the Whakapapa and Turoa skifields.

Ngati Te Rangiita representatives said they could not support the chemical's release into the environment because of concern about traditional food resources, and the degradation of Lake Taupo's water quality.

Watercare Services, which draws water from the Waikato River for Auckland, is satisfied that it will cause no problems in general use but has asked to be told of any major accidental spill.

Opus International Consultants' Taupo manager, Nick Gurr, who oversaw the trial for Transit, said soil and water scientists found the chemical much less harmful than alternatives such as salt.

He confirmed that there would be no damage to vehicles.

Each application of the chemical will last several days.

Ice is blamed for 1641 road accidents nationally between 1990 and 2002 - causing 38 deaths and 208 serious injuries.

The new solution is expected to cut the frequency and length of road closures from ice and snow, which varied from two to 20 a year on the Desert Road.