## 5 Discussion of the Australian HSR Risks  
This section highlights the paper's contributions to the theoretical understanding and practical advancement of HSR development in Australia, based on a review of relevant publications and lessons learnt from a case study investigation. The study's primary research contribution is the systematic identification, qualitative exploration, and quantitative prioritisation of key barriers hindering HSR implementation within the Australian context, employing a mixed-methodology. This provides multiple distinct insights into why HSR projects have historically stalled post-feasibility.  
Another primary contribution lies in identifying and listing reasons why mega-projects may have encountered significant time and cost overruns, and clarifying the severity of these challenges. This paper reveals that many rail and transport initiatives have faced these significant overruns, a finding reinforced by the AHP analysis, which ranked cost and time overruns as the first and second most critical barriers, respectively.  
The next notable contribution is the exploration of construction risk transfer, where our study highlights a greater-than-average risk contingency as a top priority. Although this paper does not intend to generalise the findings, it presents some information on risk allocation strategies in the selected infrastructure project.  
In addition, this work advances the discussion on the value of private sector expertise. This proposes methods to enhance private sector engagement and foster collaboration in infrastructure development, a critical step toward improving project outcomes. Finally, the paper presents a set of practical recommendations derived from these findings, or lessons learnt from the case study, which are intended to guide future HSR projects in mitigating identified risks and enhancing efficiency.  
Collectively, these contributions provide both empirical evidence and actionable insights, making this study a valuable resource for stakeholders seeking to address persistent  
Figure 8: Summary of interview results.  
challenges in HSR projects. The empirical evidence is grounded in extensive secondary research and expert interviews. P1 emphasised the originality and significance of the research, describing it as _\"quite original\"_ and _\"absolutely important\"_, and expressing his interest in reading it. P9 acknowledged the research as an _\"important project\"_, and P6 stated it \"adds to [the] debate\" around HSR and _\"enhances the credibility of [the] mega project\"_.  
Sections 5.1-5.5 provide in-depth discussions on the identified barriers and recommendations, backed by interviews, AHP survey results, and extensive literature. These sections present discussions to support further discourse on HSR and enhance the research's visibility in the field, fostering a more robust discussion on realising HSR in Australia. These contributions are discussed as follows:  
**Barriers to HSR Implementation in Australia**  
This section outlines the key barriers hindering HSR implementation in Australia. There is limited prior research summarising these barriers, so this analysis is crucial in addressing the research objectives. These themes align with the barriers identified in the literature review and are further validated through the data collected in this research.