News

Positive Results for Road Ice Treatment

Posted on 14 November, 2008 in Stornoway Maintenance News

Many Tasmanians are very familiar with the hazard posed by ice formation on public roads during the winter months. As part of our ongoing commitment to innovate and provide better services to Tasmania and the travelling public, Stornoway Maintenance has pioneered the use of environmentally friendly chemical ice treatments to assist motorists enjoy safer road conditions.

Through the application of a spray on solution, the treatment both prevents ice formation (if applied prior to icy conditions), or causes rapid ice breakdown, resulting in a safer driving environment much faster. With numerous studies showing negligible environmental impact, the treatments are considered industry best-practice and widely used in sensitive alpine areas in Australia and overseas.

Stornoway Maintenance undertook a trial of Calcium Chloride chemical ice treatment with the Hobart City Council (HCC) over a 1.3km section of road in the winter months of 2006.

The areas that were trialled with Calcium Chloride were isolated sections of road that had traditionally been subject to ice.

These locations included shaded or damp areas such as roads in gullies and near rivulets. The treatment was not required over long road lengths, rather short isolated sections were targeted for treatment.

The trial was very successful in terms of preventing ice forming on the treated sections of roads. The photo below was taken on
26 July 2006.

Ice did not form where the road was treated with Calcium Chloride. It did however form on sections of the road and the sides of the road which were not treated.

These results occurred consistently throughout the trial. Ice did not form on those sections of the road that were treated.

As a result, Mountain Park officers were not required to spread grit on the areas that were treated with Calcium Chloride.

The outcomes of this trial were very positive and resulted in the HCC engaging Stornoway Maintenance to monitor and maintain the ice affected roads on an ongoing basis.

Product
Calcium Chloride (CaCl2) is used to prevent water freezing on the roadway. It works in the same way as common salt (NaCl) to reduce the freezing point of water, thereby facilitating ice to melt and prevents water from freezing.

It is recognised that Calcium Chloride is slightly more expensive than common salt, however an advantage of CaCl2 is that it is less corrosive. It also continues to melt snow at temperatures well below those at which salt is effective.

A section of road affected by ice and the results after applying the calcium chloride product

Impact on vegetation
HCC officers engaged the University of Tasmania to provide a report detailing the likely impact the Calcium Chloride treatment would have on the vegetation surrounding the affected roads.

In summary the report advises that in the areas that were subject to the trial there was “no ecological reasons to recommend against the use of Calcium Chloride de-icing treatments”.

The report states that: “the research indicated that de-icing was unlikely to cause short or long term damage to plant communities and soils in areas with grassy verge and adjacent wet sclerophyll forest”.

Impact on corrosion
HCC vehicles were inspected and photographed before and after the trial of the Calcium Chloride. There was no evidence of corrosion on HCC’s vehicles after the trial was completed.

It is also noted that Consulting Engineers, Pitt & Sherry, were engaged by the State Government to prepare a report on the options available to deal with ice on State Government roads.

This report included advice regarding the corrosion properties of Calcium Chloride. The report states that liquids containing 25% CaCl2 and water produce 90% less corrosion than common salt. Given that a solution with strength of only 15% was adopted then it is considered that this treatment would produce approximately 95% less corrosion than common salt.

Benefits of Calcium Chloride process
Traditionally HCC’s treatment of ice on its roads has always been reactive.

When officers become aware that there are colder temperatures, they will investigate those sections of roads that typically are affected by ice.

This occurs early in the morning prior to peak hour traffic (approximately 6:30am). If ice is present they will spread “grit” onto the road. This grit is shovelled across the ice patches usually from the side of the road where the grit is stockpiled.

This provides a greater skid resistance for cars to travel across the ice. The movement of vehicles over the grit also assists in breaking up the ice.

It is recognised, however that the spreading of grit can be, in some instances, just as dangerous to motorists as the ice it is covering.

The benefits of the alternative CaCl2 treatment include:

• the treatment occurs during daylight and normal working hours;


• staff do not have to commence early or work during the dark;


• staff do not have to be on the side of the road spreading grit during slippery conditions;


• grit is not left on the road, which can be a hazard to vehicles after the ice has melted; and


• the traditional method of spreading grit commences at 6:30am. There are numerous motorists who travel on the ice-affected roads before this time.

In conclusion:

• A trial to prevent the ice formation on roads using Calcium Chloride was carried out during the winter of 2006 for Hobart City Council.


• The trial demonstrated Calcium Chloride successfully prevented ice formation.


• The trial also demonstrated this treatment provided a safer environment for motorists and HCC staff.


• At the completion of the trial, there was no evidence of corrosion on HCC’s vehicles.

The University of Tasmania advised that the treatment would not affect the ecology of the areas that were trialled.

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