Radiator roads: Preventing ice-related accidents

A thing of the past?

In what seems like a sequel to our 'solar roadways' piece a few months ago, a unique solution has been theorised to prevent the hundreds of deaths that occur on frozen highways each year as well as forgoing the need to salt and plough roadways during the winter - radiator roads.

The idea of a 'self-heating' road has been theorised by Christiana Chang at the University of Houston, Texas. In her journal, A feasibility study of self-heating concrete utilizing carbon nanofiber heating elements, she proposes a system that utilises the "conductive properties of carbon fiber materials to heat a surface overlay of concrete with various admixtures to improve the concrete's thermal conductivity".

What these means is that next time a heavy frost or snow is reported by the weather service, the state's highways commission could, in theory, activate a system that has electric heating elements installed into roads and bridges. This would in turn prevent ice forming and accidents occurring.

Ice-free driving

Chang's thesis discusses how in the laboratory, the system was tested with various compositions of concrete containing, separately, carbon fiber, fly ash, and steel shavings as admixtures. This, and another theory - to pepper concrete mix with an electrically resistive material that will convert electric current into heat, like the element of a kettle - both yielded the desired effect.

Despite this, another method was found to be more effective; using sheets of carbon nanofibres to heat the concrete.

Nanofibres comprise lengths of cone-shaped nanotubes nested "like paper cups stacked on top of each other", says Chang in her report. Bonding multiple layers of nanofibre-embedded paper beneath a chunk of road concrete that was 10 centimetres thick and 25 square centimetres in area, her team warmed it from -10 °C to 0 °C in 2 hours while consuming only 6 watts of electrical power. They also discovered that if they warmed it slower, it used less power.

Practical?

Of course in theory, like solar roads, it's a fantastic idea but is actually possible to do without bankrupting the country?

Speaking to New Scientist, Derek Carder, an engineer with the Transport Research Laboratory (TRL) seems to think so. "It's an interesting technique, but scaling it up to cover whole roads will require enormous power."

He should know. In 2007, the TRL test-trialed a self-heating road using stored summer heat in water to melt potential ice. Stored in insulated reservoirs, the warm water was pumped through a grid of pipes beneath the road during winter to prevent icing.

Unfortunately, using pumps meant the company used lots of energy - "It didn't seem viable for whole roads, but they may work for known cold spots or bridge decks," Carder said.

Chang and her Texas-based team aren't deterred however. They say their nanofibre method is much less complex as the components are already commonplace on the market, savings would be enormous. Not just that, but if their low-cost design works, it would save states millions in salting and snow plough labour every year.

One hopes, that Christiana Chang's idea is taken up and followed, after all ice and other seasonal hazards reduce car efficiency by an enormous percentage. It's possible that the system could end up paying for itself in terms of money saved.

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