Greenhouse Gas Emissions Embodied in Reinforced Concrete and Timber Railway Sleepers

In Australia, there are currently two main materials used for railway sleepers: timber (river red gum, a species of eucalypt) and reinforced concrete. Within the state of Victoria alone, there are currently seven million railway sleepers that make up the rail network. It is estimated that around two million sleepers, or 29%, are presently required to replace timber sleepers and upgrade the entire network, for which there are significant environmental implications, such as the emission of greenhouse gases. These emissions are mainly as a result of the energy and other resources required or "embodied" through the sleeper manufacture, including those associated with harvesting timber and mining raw materials for manufacturing cement. Where alternatives are readily available, it is important that the environmental impacts of the various choices are assessed, ensuring that these impacts are minimized. This study aimed to assess the life cycle greenhouse gas emissions associated with timber and reinforced concrete railway sleepers and showed that the life cycle emissions of reinforced concrete sleepers were up to six times less than the emissions associated with timber sleepers. Taking the potential errors associated with this type of assessment into account, there appears to be a significant advantage in using reinforced concrete sleepers, in terms of reducing the life cycle emissions associated with the provision of railway sleepers.