peer reviewed ; In the framework of the BRAIN-TRAINS project, the environmental impact of rail freight transport in Belgium has been analysed using the Life Cycle Assessment (LCA) methodology. The rail freight transport system has been divided in three sub-systems: rail transport operation, rail equipment (locomotives and wagons) and rail infrastructure. For the sub-system rail infrastructure, a detailed study of the life cycle phases of construction, maintenance and disposal of infrastructure has been conducted. We have collected specific information related to the Belgian railway infrastructure from both literature sources and directly from Infrabel (the Belgian railway infrastructure manager) through the use of questionnaires. The purpose of this paper is to give an overview of the methodology used to analyse the LCA of the railway infrastructure in Belgium as a part of the rail freight transport system. ; BRAIN-TRAINS