1 Transition Towards a Circular Economy in Road Construction Materials: A Case Study of Coal Ashes, Plastics, and Rubbers in Indonesia Siska Dewi 1 , Gede B. Suprayoga 2,* 1 Directorate General of Highways, Ministry of Public Works and Housing Email: siskadewi0695@gmail.com 2 Directorate General of Highways, Ministry of Public Works and Housing * Email of the corresponding author: g.b.suprayoga@pu.go.id ABSTRACT Linear economic models of consumption and production mostly dominate resource management practice in the construction industry. A transition towards a circular economy requires insights into the stages and processes associated with socio-technical transitions. This paper aims to investigate such transitions in practice. It explores two frameworks within the literature on transitions - the multi-level perspective (MLP) and transition management theory. Coal ashes (fly ash & bottom ash), plastics, and rubbers as recycled materials for road construction in Indonesia are used as a study case. The study aims to identify the critical features of such a transition in road construction in Indonesia. First, the technical standards being developed are explored. Second, secondary sources (e.g., official reports, scientific papers, regulations, and reputable news reports) were collected to gather information regarding material utilisation practices. Third, interviews with key stakeholders during discussions were conducted to triangulate information about establishing circular economy practices. The study's results show that these materials are in a different state of practice. Coal ashes are far more advanced than the rest because of accumulated knowledge in research and established collaboration with industrial actors. The use of recycled plastics is growing because of the emerging formation of value chains, but it is still in limited applications. Rubbers are seeking a window of opportunity for wide application. The lack of sustained agendas and coalitions with respective actors hinders the transition. This paper implies that advancing the technical aspects (e.g., development of standards) alone may not be helping the road authorities for achieving a successful transition towards a circular economy in road construction. Specific problem framing, mobilisation of actors, and learning from the actual applications will firmly establish the transition. Keywords: transition management, sustainable construction, recycled materials, rubbers, Indonesia 1. INTRODUCTION As a developing country, Indonesia faces significant challenges in pursuing sustainable development in many areas, including constructing and maintaining road infrastructure (1). Sustainable development requires efficient use of natural resources and the promotion of economic well-being and society (2). The conventional linear approach to development is characterised by the extraction of virgin resources, extensive waste generation, and little consideration for resource efficiency (3). Such an approach poses substantial environmental and economic burdens in the long term. In addressing these challenges, a circular economy has emerged as a transformative framework that promotes reducing, reusing, and recycling materials, fostering a more sustainable and resource-efficient in many economic sectors. The road construction industry is among those sectors significantly contributing to such a transformation (4). The interest in achieving sustainable development in the construction industry has grown in Indonesia. The Ministry of Public Works and Housing (MPWH) initially enacted a guideline for implementing sustainable construction in 2015 (5). The guideline introduces the circular economy concept by improving the extensive use of recycled materials in