11. Sustainability Issues Surrounding Unpaved Roads

The majority of the road networks in developing countries and large percentages in most developed countries are currently unpaved. This results in the road surface being directly exposed to traffic and the environment with a consequent continual loss of gravel, which needs to be replaced at regular intervals. This has severe environmental and sustainability implications and is totally unacceptable in these respects in the long term. Alternatives to this need to be developed such that the materials are either protected against environmental loss or are treated to an extent that the annual loss is significantly reduced. The optimum solution is to pave all roads with either a bituminous or concrete surfacing such that the material imported into the road is preserved against loss by erosion and abrasion. This is, however, probably not financially viable in most developing countries. The alternative is to treat the materials in some way that will reduce the annual loss. Research has indicated that, firstly by selecting the most appropriate materials and secondly, by improving construction methods, significant reductions in material loss are possible. To supplement this, methods of chemical or physical treatment can be considered to minimize material loss. Essentially, the status quo is no longer sustainable and a paradigm shift in this respect is urgently necessary. The impact of the use of water during the construction and maintenance of unpaved roads should also not be neglected.