Ballasted or ballastless for a railway infrastructure? A comparative environmental impact assessment of two solutions

In the railways sector environmental concerns are growing, and many state-owned holding companies are investigating which is the best superstructure solution from the environmental point of view. In this regards, in the last years some companies have proposed ballastless systems, to reduce the replacement and maintenance activities and increase the reliability of the solution. Nevertheless, some environmental discussion emerged, even bearing in mind of different reference service lives. This study aims at comparing from an environmental point of view a ballasted and ballastless solutions using Life Cycle Assessment, by considering a declared unit of 1 km of railways infrastructure located in Italy. Results show the ballastless system has, on the contrary of previous studies, the lower environmental impact, due to its extended shelf life (90years) and low maintenance activities if compared with a ballasted one. Considering the same timeframe, the ballastless system has about halved impact on climate change (3.33E+06 kg CO2eq) compared to the ballasted one (1.75E+06 kg CO2eq). A sensitivity analysis has been carried out to consider possible variations in reference service life, transports and interval of rails substitution.