## 6 Conclusions  
This study provided a comprehensive understanding of the early-stage risks to HSR implementation by fulfilling its core research objective: the identification and prioritisation of these risks. This was achieved by employing a rigorous mixed-methods approach, uniquely triangulating findings from the literature, expert insights, and stakeholder perspectives. The study explores the barriers specific to HSR implementation in Australia--an area with limited to no existing publications available publicly. While a wealth of studies examines general challenges faced by mega projects, including those encountered in HSR implementation globally, most Australian mega projects still proceed despite similar challenges. This suggests that unique, undocumented factors may be hindering the progress of HSR in Australia specifically, prompting the hypothesis that barriers beyond typical project challenges exist and must be identified. The primary aim of this research was to uncover these barriers and propose practical recommendations to facilitate the successful development of HSR in Australia. This publication identified five major risks in the early stages of HSR conception: improper project positioning as a mere transport project, incorrect delivery cost and time estimates, unidentified political barriers, lack of substantial private sector collaboration, and no consideration of national workforce upskilling. These pose barriers to approval. In fulfilling these objectives, this research makes a significant contribution to the field by identifying and providing industry-applicable recommendations to mitigate these risks. This publication analyses the distinct factors that have prevented the realisation of HSR in Australia thus far, offering a foundational reference for future researchers and policymakers aiming to progress HSR projects in the region. This paper presents a novel contribution to the HSR implementation by systematically documenting and analysing non-technical political, economic, and risk-based barriers that hinder project approval. This addresses a critical gap in the literature, where technical feasibility is well established globally, but context-specific challenges, considering local conditions that affect project time and cost, remain partially underexplored. Its original lies in several key advancements: First, it offers a timely analysis, aligning with the impending launch of the HSRA and ongoing HSR discussions, providing current insights into implementation obstacles. Second, it identifies and examines critical barriers, such as risk, financial constraints, and private-sector engagement. Third, it draws on practical insights from high-level interviews with influential figures in transport, government, and infrastructure, which may support theoretical frameworks with real-world perspectives. Fourth, it examines construction risk management, emphasising the importance of addressing higher-than-average risk contingencies and proposing strategies to promote private sector involvement and collaboration in infrastructure projects. Finally, the research delivers actionable recommendations derived from these findings, offering practical guidance to mitigate barriers and enhance the feasibility of future HSR initiatives. These contributions provide a unique blend of empirical evidence and strategic insights, advancing the field and supporting policy and planning efforts for HSR development in Australia. While this study is primarily exploratory and applied, it introduces theoretical lenses to interpret the findings, particularly through institutional analysis and path dependency theory. These frameworks help explain how governance fragmentation, short political cycles, and entrenched infrastructure preferences have uniquely constrained HSR development in Australia. In addition, [PERSON]'s concepts of megaproject risk, strategic misrepresentation, and political influence were used as a foundational lens to contextualise decision-making challenges.