An innovative conductive asphalt capable of melting ice and snow is being tested in the United States. It is safe and non-polluting, unlike salt and chemical de-icers.
Hands up anyone who, while driving in a snowstorm or on a freezing winter morning, has not longed for a gritter to come along and tackle ice and snow. A perfectly reasonable wish, but one with far from positive consequences for the environment. Salt and, more broadly, the antifreeze products spread on road surfaces do indeed improve safety, but they have a severe impact on nature. On top of their weed-killing effect, they destroy the microfauna and microflora in the surrounding soil, and there is also a risk of groundwater contamination. Rainfall, in fact, "washes" the roads, carrying the scattered products deep into the ground. This is a situation that could be averted thanks to the development of a revolutionary conductive asphalt.
Conductive asphalt incorporates steel shavings and carbon particles in a quantity equal to 20 per cent of the overall "mix". A relatively modest proportion, yet sufficient to allow the diffusion of low-voltage electrical energy — meaning there is no risk in the event of direct contact. This energy heats the road surface, thereby preventing snow from settling or ice from forming. Developed by researchers at the Peter Kiewit Institute in Nebraska, United States, the novel conductive asphalt has attracted the interest of the Federal Aviation Administration (FAA) — the agency within the US Department of Transportation responsible for regulating and overseeing every aspect of civil aviation — drawn by the possibility of applying the new asphalt at airports across North America.
The FAA would like to resurface all the service roads at the main airports in the United States, so as to solve the problem of snow clearance and ice formation, ensuring full mobility for service vehicles during winter. This is by no means a utopian goal, especially considering that in Nebraska conductive asphalt has already proved its worth. The Roca Spur Bridge, a 36-metre-long bridge on the outskirts of the city of Lincoln, has used this type of surfacing since 2002. Despite heavy traffic and harsh weather, the special "electric" surface has so far required no special maintenance and, at the same time, has prevented road accidents from occurring. This result is all the more noteworthy when one considers that bridges freeze very easily, being exposed to the elements from both above and below.
Building entire road networks in conductive asphalt would involve excessive expenditure for public authorities, but it could represent a sustainable alternative to spreading chemical antifreeze products in certain mountain areas or wherever infrastructure such as airports and viaducts is present. Electrifying the Roca Spur Bridge, for example, costs 250 dollars (approximately 236 euros) to combat a three-day snowstorm: far less than a lorry-load of chemical substances.