Opportunities for GHG emissions reduction in road projects: a comparative evaluation of emissions scenarios using CO2NSTRUCT

In the road construction sector, a number of measures and alternatives have been proposed to reduce the emissions of greenhouse gases (GHG). While these measures can result in a notable abatement of this impact, when analyzed independently and in absolute terms, they are not equally relevant within a common context, such as a complete road transport infrastructure project. In this work, we analyze a broad range of scenarios for emission reduction combining plausible options given the current state of technology and involving those elements of road construction and maintenance with major contributions to the total balance of emissions. The selection of scenarios goes beyond the usual perspectives focused on pavements and materials, and includes other factors dealing with machinery, transport distance, energy sources, land-use change, as well as combined scenarios intended to find optimal alternatives. This has been achieved using the tool CO2NSTRUCT, which considers a life-cycle assessment approach for road transport infrastructure in evaluating GHG emission, thus providing an adequately comprehensive context for comparing relative contributions. This common reference enables to accomplish the ranking of the possible solutions. Results indicate that strategies involving the use of construction materials with lower emissions in their production process and recycled materials are the most effective, followed by those using lower-pollutant sources of energy in both off-road and transport machinery and lighting. This research also shows that the process of selection of suitable options should consider not only the construction stage but also the maintenance stage spanning road service life. Furthermore, the study demonstrates the importance of performing these analyses within a reference framework, enabling the identification of more efficient strategies amongst the universe of alternative solutions to mitigate GHG emissions.