Analyzing the environmental Kuznets curve hypothesis: The role of disaggregated transport infrastructure investments

The provision of affordable and sustainable transport systems is a crucial issue for both the establishment of sustainable cities and the development of society. It is a significant part of the Sustainable Development Goals (SDGs). In this paper, we aimed to unveil interactions between infrastructure investments in transport systems and environmental degradation in 21 Organisation for Economic Co-operation and Development (OECD) countries. The empirical findings can be summed up as follows: (a) there is a long-run relationship between variables; (b) gross domestic product (GDP) per capita has a positive and statistically significant coefficient, while GDP per capita square has a negative statistically significant coefficient, and therefore, the environmental Kuznets curve (EKC) hypothesis is valid (c) additionally, rail infrastructure investment has a negative and statistically significant parameter sign, whereas road and air infrastructure investments have a positive and statistically significant parameter sign; and (d) trade openness has a positive and statistically significant coefficient. Hence, rail investment helps achieve the establishment of sustainable transport systems and low-environmental pollution targets of SDGs, whereas road and air investments hamper their establishment.