## 5 Conclusions and Limitations  
The study proposes a framework to facilitate the transition towards circular economy in construction mega-projects, using case studies from the kingdom of Saudi Arabia. The Interpretive Structural Modelling (ISM) based on data collected from three distinct mega-projects (buildings, urban development, and infrastructure) demonstrates a structured approach to understanding the relationships between CE enablers. The ISM analysis provides various key findings that are vital for the transition to CE in construction mega-projects. The progression of analyses revealed E1 \"Establishing clear law and legislation\" and E4 \"CE initiatives\" as the driving enablers that significantly impact entire schemes. Other dependent enablers, including E5 \"Advanced technology related to CE\", E6 \"Developing a mature market and supply chain\", E11 \"Cost reductions for materials and construction\", and E12 \"Ensuring data availability\" are successfully achieved by addressing the requirements established at separate levels. Furthermore, linkage enablers such as E2 \"Raising awareness of CE\", E3 \"Education and training\", E7 \"Examples and existence of case studies that adopt CE principles\", E8 \"Promoting a culture of acceptance of reclaimed materials\", and E9 \"Providing incentives to adopt CE\", play a crucial role in the framework's success. E10 \"Certification of reclaimed materials\" is considered an autonomous enabler that has less criticality within the framework. This study aims to underpin circular economy in the construction sector, particularly in the context of mega-projects. The data gathered incorporate views and perspectives expressed by key stakeholders, providing a broader insight to the framework. Notably, the study collected data from three case studies in the Kingdom of Saudi Arabia, where there is no framework yet in the field of circular economy within this context or for mega-projects. We believe that the use of Interpretive Structural Modelling (ISM) to examine CE enablers is a novel approach that offers new insights on how CE transition can be achieved utilising its advantages such as minimising construction waste. Its contribution lays a foundation for future research across different regions and contexts. Although the developed framework serves as a strategic tool for decision makers and key stakeholders to adopt CE principles in construction mega-projects, it does not consider potential changes in the regulations or advancement of technologies. Furthermore, this study was limited to Saudi Arabia's mega-projects and targeted experienced high-profile participants. Future studies could consider validating the method and expanding it to other  
Figure 3: MICMAC analysis of the CE enablers. contexts and industries, as well as applying it to smaller projects to broaden its applicability and impact. To accelerate the transition towards CE, collaboration among decision makers and key stakeholders in the industry is essential. The developed framework can be utilised as a roadmap to prioritise the necessary actions. The adoption of CE in construction mega-projects can be advanced by considering EU initiatives, as these are in the forefront in this field. The European Union has established regulations, policies, case studies, and best practices such as those presented by CircularB [47]. Incorporating these practices can facilitate the transition towards circularity in the construction industry. Conceptualisation, S.A. and C.B. ; methodology, S.A.; software, S.A.; validation, S.A., C.B. and P.M.-V.; formal analysis, S.A.; investigation, S.A., C.B. and P.M.-V.; data curation, S.A.; writing--original draft preparation, S.A.; writing--review and editing, S.A., C.B. and P.M.-V.; visualisation, S.A., C.B. and P.M.-V.; supervision, C.B. and P.M.-V.; project administration, S.A., C.B. and P.M.-V. All authors have read and agreed to the published version of the manuscript. This research received no external funding.