The contribution of a road network to sustainability implies consideration of externalities beyond the usual engineering considerations of maintaining a durable system of sufficient capacity. In a geologically old country, such as Australia, construction materials of high quality are scarce placing emphasis on the prudent use of non-renewable resources and the encouragement of recycling.
Construction and maintenance of Low Volume Traffic (LVT) roads (roads with less than 0.26 Million Vehicle Kilometres Travelled per Kilometre Lane Length) has an effect on the environment beyond that of providing transport and supporting the social fabric of society.
There is the impact on ecosystems, agricultural cohesion and pollution. The contribution of the system to pollution and the generation of greenhouse gases must be considered.
This paper offers an outline policy for the sustainability of the LVT road system that considers factors affecting the engineering aspects of the system as well as the externalities present because of the existence of the road network.
Sustainability of a Road System
The definition of sustainable development has been stated as "Development which meets the needs of the present without compromising the ability of future generations to meet their own needs", (Brundtland, 1987).
"Sustainability is a systemic concept, relating to the continuity of economic, social, institutional and environmental aspects of human society. It is intended to be a means of configuring civilization and human activity so that society, its members and its economies are able to meet their needs and express their greatest potential in the present, while preserving biodiversity and natural ecosystems, and planning and acting for the ability to maintain these ideals in the long term. Sustainability affects every level of organization, from the local neighbourhood to the entire planet" (PIARC, 2007a)
The introduction of the "Triple Bottom Line" was an attempt to widen the basis beyond economic considerations on which company performance was judged to include the environmental and social impact of company operations. An expansion of this approach was the introduction of the concept of Corporate Social Responsibility (CSR) defined by the World Bank as "the continuing commitment by business to contribute to sustainable economic development by working with employees, their families, the local community, and society at large to improve their quality of life, in ways that are both good for business and good for development"
The sustainability of the LVT road network requires that it supports the demand traffic flow with a minimum of disruption at the least cost to the community (cost being a measure of energy) and with the least possible pollution and it also supports the social framework in such a way that the resource consumption, in providing the asset, is kept at the lowest possible level. It also provides access to the main supply routes. In other words, the asset provides the necessary service at the least cost with the lowest resource consumption.
Australian Road Network
The road network in Australia has developed in a country that is large and sparsely populated.
The landmass is approximately the same size as the continental United States but contains a population of 21.3 million, which is nearly equivalent to that of the State of Texas (22.9 million). The Australian population is mainly concentrated in urban areas dotted throughout the continent, but essentially located in a strip along the Eastern seaboard.
The Australian road system has a length of almost 800,000 kms. The categorisation of the system into its various components is shown in Fig 1.
[FIGURE 1 OMITTED]
The road density in terms of length of road per area of land is one of the lowest in a group of nine nations sampled (Australia, Canada, France, Indonesia, Japan, New Zealand, South Africa, UK and USA). …