The European making of circular economy for transport megaprojects. Insights from a Trans-Alpine Tunnel

The European Union is undergoing a shift: over the past decades, what was once a framework built primarily on economic growth, acceleration, and intensifying connectivity is now being driven to integrate environmental concerns. The development of the Trans-European Transport Network (TEN-T), based on several infrastructure megaprojects that must comply with environmental requirements such as reducing waste production, illustrates this transition. However, many of these projects involve underground construction, including tunnels, which generate substantial quantities of excavated material. One proposed solution is the circular economy (CE), which focuses on reusing these materials. Our article first retraces the institutionalization of environmental concerns within European directives, particularly those related to CE. This top-down analysis reveals that developments in this field result from a co-production process between public and private actors aligned with industrial interests and constraints, leading to conflicting commitments. Second, drawing on an ethnography-inspired approach, we analyze how these legal evolutions materialize in practice, within a specific TEN-T project: the construction of the Lyon–Turin tunnel. The findings from the bottom-up approach reveal that industry actors deploy technical strategies and engage in regulatory negotiations to promote CE practices. Combining these two analytical scales highlights the inherent structural tensions in the construction of megaprojects, between the imperative to increase productivity and the pursuit of environmental sustainability and circularity. This dual perspective demonstrates that CE is simultaneously shaped at multiple levels (European, national, and local) and by diverse actors (industries, regulators, and policymakers), which reinforces the contradictions between growth logics and a greening policy agenda.