Many governments around the world have to carry out extensive de-icing to keep roads safe and congestion free during the icy winter months but sourcing cost-effective, efficient and environmentally friendly systems using innovative materials and technology is not always easy.

Road Traffic Technology investigates some of the options operators and governments around the world have come up with that meet modern day requirements within current budget constraints.

A first for pre-wet salt in the UK

As the big chill hit this winter in the UK, the preservation of salt stocks and the need for more effective de-icing processes was high on the agenda.

Following a £45m investment from the Highways Agency, a state-of-the-art fleet was deployed in England to scatter pre-wet salt to help prevent the formation of ice in advance of predicted snowfall.

“Pre-wet salt reacts more quickly when it hits the carriageway and sticks to the road surface,” says a spokesperson for the Highways Agency, when comparing it with the previous de-icing process.

“Highways Agency invested £45m in a fleet to scatter pre-wet salt to prevent ice forming.”

To further ensure that salt is used efficiently, Cybit’s data logging systems have been installed in each vehicle. “The data logger is able to record information, including salt type, spread rate, vehicle speed, CO2 emissions and treatment times,” adds the spokesperson.

In addition, the country’s first fixed automated spray technology (FAST) bridge deck system from Vaisala and EnviroTech was installed by the Kent County Highway Authority to help fight the ice, and improve public safety and traffic flow.

The technology uses non-intrusive sensors to measure depth of moisture (water, snow or ice), grip or friction factors, and air and pavement temperature, and is monitored remotely over the internet. If treatment is required, 30 non-invasive spray nozzles apply liquid de-icer to the road at appropriate levels.

The US improves brine production

The US spends $2.3bn annually on winter maintenance and uses about 15 million tons of de-icing salt. New technology to improve best practices and minimise environmental impact is regularly implemented, and FAST systems are already installed around the country.

“The US spends $2.3bn annually on winter maintenance and uses 15 million tons of de-icing salt.”

To improve brine production and make it more cost effective, Cargill Deicing Technology has produced an automated brine maker, AccuBrine. The product has recently been successfully introduced to The City of Beloit, which won the Excellence in Snow and Ice Control award from the American Public Works Association (APWA) in 2009. AccuBrine currently has over 100 units in operation in North America.

Iowa’s Department of Transport has been carrying out thermal mapping of roads with the goal of eventually creating custom de-icer applications by combining de-icer technology with pavement temperature.

“A highway’s surface temperatures are affected by weather and differences below the roadway surface,” reports Dennis Burkheimer for the Bureau of Research and Technology. “In the future, understanding these differences could lead to customised treatments for roads.” Research will continue throughout 2010.

Canada trials pre-mixed de-icer

In a bid to reduce mixing costs and improve the de-icing process even in the coldest of temperatures, trials have been held by the Ministry of Transport in Ontario, Canada, on a product called Thowrax.

Produced by Sifto Canada Corp, a Compass Minerals subsidiary, the pre-mixed product is being tested against pre-wetting treatments to see if it could be an alternative source of road salt. It contains rock salt, magnesium chloride and an environmentally-friendly viscosity modifier, which works in temperatures as low as 30°F (12°C).

“Ontario, Canada plans to reduce mixing costs and improve the de-icing process.”

“Thawrox will allow salt users to clear roads in the most challenging weather conditions and realise cost and efficiency benefits,” says Keith Clark, vice president and general manager of North American Highway at Compass Minerals.

“Because Thawrox is premixed, it allows municipalities to get the benefits of a high-performance de-icing product without the investment in specialised mixing equipment,” Clark adds.

The product will be marketed under the name Maxifonte in Canada’s French-speaking regions.

Norway decreases construction downtime with de-icer

Sometimes de-icing products are needed to ensure construction work continues on time and within budget. In Norway, the de-icing product Kilfrost 400 is aiding the construction of a new highway just outside the Arctic Circle. The road, running from Tverland to Godøystraumen, experiences harsh cold weather, but the implementation of this product means that downtime is minimal.

“Construction workers face a daily battle against the elements,” explains Kilfrost’s chief executive Gary Lydiate. “Our K400 product is drip fed into the airline of tools to stop condensation or water icing by depressing the freezing point of the solution formed.”

To Russia with ice physics

Dartmouth College’s engineering department has reported that Russia has placed orders for Ice Engineering’s variable resistance cable (VRC) de-icing system. Co-designed by engineering expert Professor Victor Petrenko, the system keeps ice off power cables cheaply and efficiently.

“The technology builds on many years of research in materials, science, power electronics and ice physics with my colleagues at Dartmouth, such as Professor Charles Sullivan, an expert in power electronics and a co-inventor of the VRC de-icer,” says Petrenko, who is the founder of Ice Engineering.

“Ice Engineering’s cable de-icing system keeps ice off power cables cheaply and efficiently.”

Ice Engineering previously designed pulse electro-thermal de-icing (PETD) technology, which was installed on the Uddevalla cable bridge in Sweden in 2005 and found to remove ice with great efficacy. Now launching VRC, the company says this new proprietary technology is completely customisable.

“It’s an affordable addition to the current manufacturing and installation process,” says Gabriel Martinez, the vice president of Ice Engineering, who goes on to explain that implementing the VRC system would result in a less than 10% increase in overall cost.

The lifespan of the system would match or exceed that of the cable (between 30 and 50 years) and can be controlled automatically with electronic sensors.