Salt the roads? Sugar works far better in big freeze, councils find

• Transport authorities are looking for innovative ways to tackle ice on roads, and Huntly, above, has seen testing of new treatments

A range of sugar-based chemicals is being mixed with salt to clear ice and hard-packed snow in temperatures below -8C.

The products cost up to 12 times as much as salt, but would only be used in extreme conditions. The Scottish Government's Transport Scotland agency, which commissioned the trials in Aberdeenshire, said the chemicals worked in temperatures down to -20C but did not harm the environment.

Some are already used by local authorities such as Glasgow City Council, but this is the first time they have been tried on trunk roads, which are currently treated with brine - salt solution.

They have been extensively used in the United States and Canada.

A 20-mile stretch of the M8 between Harthill and Edinburgh was shut for nearly two days last month because of ice and snow on one carriageway.

The trials involve a range of chemicals being mixed with salt in varying quantities to test their effectiveness. They are sprayed on roads using special tanks carried by existing gritter lorries.

Airports and railways use special de-icers that do not corrode aircraft, trains and tracks.

Transport minister Keith Brown said: "This is one of the first times this treatment has been used on the Scottish road network and it is encouraging to see this initial trial deliver positive early results.

"We will continue to explore innovative ways of keeping our transport networks moving and Scotland open for business."

One of the trials, in Huntly, involved salt being mixed with Eco-Thaw, which is made from agricultural by-products, such as those used in fermenting.

Camillus Dunne, chief operations director of manufacturer Innovative Global Products, said it helped accelerate ice melting.

Stocks will now be sited around the country to be used in very low temperatures.

The trials also involve magnesium chloride, a different type of salt to rock salt, and Safecote, based on molasses from the sugar industry. The chemicals cost up to 420 a tonne compared to 35 for salt.

Motoring groups welcomed the trials. Neil Greig, policy and research director of the Institute of Advanced Motorists, said: "We are pleased to see such a quick response to the packed ice problem. Trying to second-guess a Scottish winter will never be easy, but the more options that road authorities have to keep traffic moving the better."

The Scottish Environment Protection Agency said it was assessing the impact of the tests. A spokeswoman said: "We have been in discussions with Transport Scotland about their trial of alternatives to salt and grit at low temperatures and will be working closely with them to assess the results. These trials will help us determine whether there are any environmental risks."