Roads play a very important part in any nation’s infrastructure. Their construction and maintenance, and the vehicles that travel over them, consume large amounts of energy. This energy use results in atmospheric emissions, the reduction of a non-renewable resource, and other environmental impacts. Any reduction of the lifetime energy use associated with roading, even if only by a small percentage, will have significantly positive implications for sustainable development.
Concrete roads are durable and safe. They are considerably less prone to wear and tear defects like rutting, cracking, stripping, loss of texture, and potholes that can occur with flexible pavement surfaces. This low maintenance requirement is one of the principal advantages of concrete pavements. There are well-designed concrete pavements that have required little or no maintenance well beyond their 40-year design lives. Less maintenance also means fewer traffic delays, a huge advantage on some of our already congested highways.
Fuel consumption is a major factor in the economics of roading, with the rolling resistance of the pavement being an important contributor to the fuel consumption and the corresponding CO2 production. Rolling resistance can be attributed in part to a lack of pavement rigidity. In the case of a heavily loaded truck, energy is consumed in deflecting a non-rigid pavement and sub-grade. Using rigid concrete pavement will result in less fuel consumption, and a decrease in associated emissions.*
In New Zealand, concrete pavement, such as the Peanut Roundabout near the Port of Napier (Case Study 6), is currently restricted to areas requiring high-strength roading components. This is mainly as a result of first-cost rather than a whole-of-life cost approach. The lifetime costs of concrete roads are, however, lower than asphalt.
Another benefit of using concrete as opposed to alternative flexible pavements is a reduced need for street lighting, due to higher surface reflectivity after dark. Better light reflection on the brighter surface could potentially result in electricity savings of about 30% for lamps, lampposts and signs.** However, the largest savings from higher surface reflectivity are to be gained from a reduction in accidents, and the associated loss of life and serious injury.
*Jamieson, N.J. & Cenek, P.D. (1999). Effects of pavement construction on the fuel consumption of trucks. Options for a post millennium pavements symposium. New Plymouth. New Zealand Institute of Highway Technology. 1999.
**Young, S. Turnbull, S. & Russell, A. (2002). What LCA can tell us about the cement industry? An independent study commissioned by the WBCSD.