Sustainable Engineering Solutions in Construction and Operation of Railway Infrastructures

Railway transport is widely recognized as one of the transport modes that generate the lowest CO2 emissions and energy consumption during operation. However, during the construction and maintenance phases (non-operational phases), CO2 emissions and energy consumption are higher than those of other transport modes. This gap between operational and non-operational phases call for research efforts aimed at improving practices and materials of construction in ordet to minimize the negative effects on the environment and society, and to make the transportation mode more sustainable. To this aim, the use of recycled materials (crumb rubber (CR) from end-of-life tyres (ELTs), and reclaimed asphalt pavement, RAP) is recognized as a promising practice also in the context of the circular economy based on three key principles: eliminating waste and pollution, keeping products and materials in use at their highest value, and preserving natural resources. Within the Green Deal action plan issued by the European Commission to reach climate neutrality by 2050, the circular economy is identified as a key driver towards an energy-efficiency society and transport systems. Other promising applications include the use of geosynthetics (e.g. geogrids and geocells) as reinforcement in railway infrastructure. When placed in the track substructure, geosynthetic layers can enhance stability and, consequently, increase the durability of ballasted railway tracks. Assessing the real performance of the abovementioned materials and technical solutions requires the consideration of multiple impact categories and the use of robust methodologies (e.g., Life Cycle Assessment, LCA) applied over the entire life cycle of railway infrastructure. In this study, the results of environmental analyses applied to these construction and maintenance solutions are presented and discussed. The assessment of the environmental impacts associated with the use of these innovative materials, compared to traditional ones, confirms their suitability in supporting the objectives of the circular economy and environmental sustainability in the railway sector.