Investments in local public transport: A systematic literature review on evaluation methods with a focus on the role of uncertainty

This paper presents a systematic literature review for Local Public Transport (LPT) investment evaluation, with a particular focus on how uncertainty is addressed. It identifies the main methodological approaches – such as classic Discounted Cash Flows (DCF) methods, Cost-Benefit Analysis (CBA), Total Cost of Ownership (TCO), Life Cycle Costing (LCC), and constrained optimization models – and examines their underlying assumptions, cost structures, and degrees of complexity. The review also maps the most frequently adopted evaluation variables across economic, environmental, technical, and infrastructural domains. Particular attention is devoted to how recent studies incorporate uncertainty, through tools such as scenario analysis, sensitivity testing, Monte Carlo simulation, and Real Option Analysis (ROA). Beyond methods and variables, the paper analyses the evolving objectives of LPT investment studies, tracing the shift from a narrow focus on financial efficiency toward broader goals such as decarbonization, social inclusion, and infrastructure resilience. By combining methodological classification with thematic analysis, this work provides a comprehensive overview of the analytical evolution in LPT appraisal and highlights areas for future research. The review highlights that, despite the LPT sector undergoing ecological transition, digitalization, and broader technological evolution in a context of high uncertainty, most studies still rely on static and deterministic methods. This gap limits the ability of current evaluations to address volatility and guide effective investment decisions under uncertainty.