The life cycle assessment methodology is used to describe the environmental impact and energy consumption of roads and pavements as well as the use of resources for road and pavement construction. Within a project at VTI, European life cycle assessment studies have been compiled.
The energy use due to transport is considerable, around 30 per cent of the total energy use in Europe. Road transport is responsible for a large part, more than 80 per cent, and since it is mainly fossil fuel that is used, the emission of greenhouse gases is substantial. Added to this is the energy used for building, operation and maintenance the infrastructure i.e. roads, railways etc. The infrastructure of roads is also an important factor, not only because of the environmental impact and resource use due to building and maintenance but also because of the effect it has on the fuel consumption of the vehicles due to road alignment and rolling resistance.
In this report a number of scientific studies using the life cycle assessment methodology to study roads and pavements are described shortly. The report is limited to European studies that can be considered the most relevant and that have been performed since the mid-1990s.
One conclusion of the compilation is that the results of these studies are not directly comparable since the underlying prerequisites differ. For instance they include different stages in the life cycle and also different aspects of the environmental impacts. Other differences are the design of road construction and the number of years for which the environmental impact is estimated. Another important difference is the focus of the studies. For example, some make comparisons of asphalt and concrete pavements, whereas other compare the alternatives either to deposit the waste materials, for example slag, or to use them in road construction.
A common result is the conclusion that all roads are unique and have their own specific conditions, which means that a flexible method is needed that can be adjusted to suite the road you want to study. Also, the studies that have in some way estimated the energy use due to traffic have concluded that the energy used for construction, operation and maintenance of the infrastructure only amounts to a small part of the energy use for traffic. A conclusion of this is that if the purpose is to make road transports more energy efficient it can be better to accept higher energy use for the infrastructure if it leads to lower fuel use of vehicles, since it can result in lower total energy use.