Environmental governance in railway megaprojects: a stakeholder framework and validated empirical model

Environmental risks routinely delay, inflate, and discredit railway megaprojects, yet guidance on how to govern these risks remains fragmented and sector-agnostic. This study addresses this gap by developing and empirically validating a unified environmental governance framework tailored to railway transport infrastructure. A structured review of 38 peer-reviewed articles and technical reports (2010–2025) maps decision-making roles of six core stakeholder groups: governance agencies, funding institutions, internal project teams, environmental organisations, community groups and the media, across the project lifecycle. These insights are distilled into six propositions linking stakeholder mechanisms to practical environmental and performance outcomes.The framework is empirically validated through three contrasting case studies: California High-Speed Rail, the Fehmarnbelt Fixed Link, and Tanzania’s Standard Gauge Railway, utilising documentary evidence and publicly available monitoring data. Results show that inclusive, transparent, and adaptive governance mechanisms reduce schedule slippage, mitigate cost escalations linked to environmental revisions, and improve compliance with biodiversity and emission standards. This study makes two contributions. Practically, the study offers a step-by-step checklist enabling policymakers, sponsors, and contractors to embed environmental safeguards from feasibility through decommissioning. Theoretically, it integrates stakeholder, adaptive governance, and megaproject literatures into a transferable actor–mechanism–lifecycle model. The framework equips policymakers and scholars with a ready-to-apply tool for aligning railway investment with climate and biodiversity goals. The study concludes with recommendations for future research to strengthen environmental governance and performance in transport infrastructure.