## 1 Introduction  
The construction industry is able to enhance urban and socio-economic development including through enforcement of sustainability development goals (SDGs). Therefore, addressing the sector's environmental and resource challenges through a more sustainable approach is crucial for long-term development [1; 2; 3; 4]. One key aspect of the transition towards CE is the reduction of materials and energy consumption while closing the loop on materials use [5; 6; 7]. This new paradigm, named circular economy, redefines the construction industry as a \"system where materials never become waste and nature is regenerated...\" [8]. It is a global challenge to facilitate this transition, leveraging societal benefits and waste reduction through decreasing reliance on raw materials and the adoption of more sustainable and efficient resource management. Past research has identified a variety of schemes for integrating circular economy into the construction sector. International efforts are being led by countries and institutions around the world that have developed legislation and technologies to accelerate the transition to circularity. Locally, we have the British Standards (BS8001) [9], and RESOLVE (Regenerate, Share, Optimise, Loop, Virtualise, Exchange) introduced by the Ellen MacArthur Foundation [6] to mention a couple of examples. Separate studies have also emphasised the need for clear, practical guidance, tailored to the context where the construction industry operates [10; 11]. Yet, CE principles and models differ amongst sectors and regions, highlighting the need for sector-specific frameworks that address the complexities and demands of civil engineering construction [3; 12; 13]. The literature review undertaken for this study revealed that, to date, most studies have focused on small-scale projects often involving buildings [14; 15; 16; 17]. A few other studies have specialised in strategies of design for deconstruction and design for flexibility [3; 11; 18], although on some occasions these studies have merely identified barriers, drivers, and strategies of CE without structuring broader pathways for specific context; for an example, see [19]. In fact, several frameworks over-rely on theoretical solutions with limited consideration of practical issues, making them unsuitable for generalisation--for example, ref. [20] focuses on existing buildings but does not address those under construction. Furthermore, previous studies that explore CE overlook the contextual relationship between the enablers in large construction projects like mega-projects. This leaves room for frameworks that facilitate the adoption of CE once the complex relationships between enablers have been understood, particularly for large-scale and infrastructure projects. Examples of studies that emphasise the importance of having a framework to support the adoption of CE in construction projects can be found in [1; 7; 10; 11; 21]. This study aims to address gaps in CE frameworks within construction using Interpretive Structural Modelling (ISM), with a particular focus on mega-projects under construction in Saudi Arabia. Mega-projects are characterised by their high risk, substantial costs, significant impact, and the involvement of various stakeholders [22]; hence, understanding and resolving the challenges involved open opportunities for generalising the implementation of CE principles. Economic transactions derived from construction activities in Saudi Arabia represent approximately 6% of the nation's GDP and provide around 3 million jobs [23]. However, the industry also generates a significant amount of construction waste, averaging 55 tons per 1 km\({}^{2}\) of construction [24], which is one of the various reasons for adopting CE if we want to reduce CO\({}_{2}\) emissions and preserve natural resources [1]. In this research, we used ISM to analyse the relationships between the main enablers of CE in construction mega-projects, as previously identified by [PERSON] et al. [1].