The efficiency of urban public transport and its impact on environmental sustainability

Promoting and popularly developing urban transport improves environmental sustainability by reducing traffic congestion and air pollution. In the last decade, bus and metro modes, in addition to being the most in-demand, have been the most utilized to offer a practical and sustainable public transport system. In Spain, public transport services are bus, the mode of transport designed as a priority over metro. The significant investment in infrastructure required for its implementation and maintenance makes it necessary to assess these companies' efficiency and impact on the sustainability of the surrounding environment. For this reason, this study aims to analyze if the bus mode is more efficient and sustainable than public transport by metro. The sample comprises companies providing bus and metro transport services in four of the biggest cities in Spain during the period 2017 - 2021. The methodology used will be (1) a description of the main variables of these companies and (2) a data envelopment analysis and the Malmquist index as statistical inference estimators to provide the productivity, efficiency change (EFCH) into Pure Technical Efficiency Change (PTECH), and Scale Efficiency Change of the analyzed companies. This analysis's main result shows that bus and metro efficiency is similar for the analyzed cities. This study contributes to the academic literature because the comparative analysis by modes of transport has not been conducted and can be considered an influential variable when it comes to resource allocation, controlling the services provided, and improving the planning of these services by the competent authorities.