Imagine a road surface that turns pink when cold. A new road varnish developed by a French firm, Eurovia, promises to do just that. Road surfaces treated with the varnish change colour, so drivers would be warned when roads turn icy.
Looking after road surfaces accounts for almost half of a country’s road budget, and a safe, comfortable and durable road surface could substantially cut the costs and frequency of road works, and save time and money for road users too. Whether a road varnish is a solid investment is a debatable point; what does matter is the quality of materials beneath the surface.Long-life Surfaces for Busy Roads presents the results of research that evaluated the technical and economic potential of the most promising long-life pavements. Phases one and two of this International Transport Forum project confirmed the viability of two surfaces in particular, epoxy asphalt and high-performance cementitious materials (HPCM). These cost two to three times more than conventional asphalt, but lengthen durability from around 10-15 years to 30-40 years (see “Smoother surface
”, in OECD Observer No 251, September 2005, www.oecdobserver.org
).The Shell Oil Company developed epoxy asphalt in the late 1950s as a jet fuel and jet blast resistant specialty pavement for airfields. In 1967, a wafer-thin layer of epoxy asphalt was used for its first commercial roadway application on the deck of the San Mateo- Hayward Bridge across San Francisco Bay. After 40 years, the surface is still functioning under extremely heavy use, with 30,000 cars peeling through each lane per day, and the total passage of over 250 million vehicles.HPCM consists of ultra-high performance, steel fibre-reinforced fine mortar, in which hard, polish-resistant aggregate particles are embedded. Testing has shown that a 10-30mm layer of HPCM shows great strength and integrity, and may be practically maintenance-free for 30 years.Both materials will now be tested on heavily trafficked roads. This phase of the project will look at glow paint adherence, noise levels, skid resistance and safety in wet conditions, as well as its ability to be quickly mixed, applied and dried.
©OECD Observer No 267 May-June 2008