The main purpose of this study is to demonstrate how modifications in the infrastructure of a railway carrier contribute to reducing the negative environmental impact, thus aligning with the principles of sustainable development. This study employs a combination of theoretical and empirical approaches. The theoretical aspect involves a literature review, which explores the theoretical aspects of sustainable development, as well as transport policy and the challenges of rail transport in Poland in relation to sustainable development. The empirical dimension is showcased through a case study of a railway carrier that has implemented changes to its infrastructure. The changes made have led to a reduction in the "dead weight" of trains. As a result, the carrier has increased its competitiveness while also generating environmental savings, thus supporting the implementation of sustainable development policies. The exploration of reducing the dead weight of trains in relation to the transported load highlights the need for further research. Future studies could focus on analyzing the innovative processes involved in implementing such changes or exploring the potential application of similar modifications in other modes of transportation.