Applying life cycle thinking to reduce greenhouse gas emissions from road projects

In this article, the evaluation of Greenhouse gases in road construction projects is approached from a life cycle perspective. The elements which have a major contribution to emissions are identified in order to develop a strategy to control and reduce them. For this purpose, a management information system (CO2NSTRUCT) was developed, supported by a database obtained through specialized bibliography. The information in the application is organized in a manner that permits a wide variety of queries with several grades of detail in order to study the results. Four new construction projects in Spain were analyzed. The scope of the analysis and the results are contrasted with an extensive revision of the state of art. The total emissions obtained in the life cycle range from 8880 to 50 300 t CO2e/km, most of them related to road construction activities; the maintenance stage has a secondary role. Earthworks are the main activity involved, with 60-85% of the emissions in the construction stage, strictly related to the emissions generated by the performance of off-road machinery. Materials, land use and land-use change result significant and crucial contributions. The obtained results constitute a necessary base in order to accomplish an adequate dimensioning of emissions in the road construction sector.