International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The liberalisation of European passenger rail markets under the EU’s Fourth Railway Package confronts suburban rail operators with a fundamentally new competitive environment. Where incumbents once operated under protected concessions, they now face the prospect of open-access competition and competitive tendering. This paper proposes a two-dimensional model of competitiveness centred on eco-efficiency and service quality — treated not as independent performance metrics, but as mutually reinforcing drivers of long-term market position. Eco-efficiency is defined as the ratio of transport output, measured in passenger-kilometres, to the energy and resource inputs required to achieve it, including CO₂ emissions. Service quality is assessed across five dimensions: reliability, passenger comfort, rolling-stock condition, accessibility, and the onboard environment. Drawing on European comparative practice and a focused analysis of the Plovdiv–Karlovo suburban corridor in Bulgaria, the paper demonstrates that these two dimensions operate in a relationship of synergy. Modern, energy-efficient rolling stock improves the passenger experience and raises load factors, which in turn yields further gains in eco-efficiency. The corridor analysis illustrates both the potential and the current constraints facing operators in a post-socialist railway context.
An examination of existing Public Service Obligation (PSO) frameworks reveals a structural misalignment: current subsidy schemes are oriented predominantly toward maintaining geographic service coverage, rather than rewarding environmentally efficient and high-quality delivery. This creates an incentive structure that may discourage investment in precisely the capabilities that would enhance competitiveness under liberalisation. The paper concludes with targeted recommendations for reorienting performance indicators and funding mechanisms toward the proposed dual-driver model, with the aim of placing suburban rail development on a more sustainable and competitive footing.