Implementation of Regulatory Strategies for Coal-Based Solid Waste Material Utilization in Road Engineering: An Evolutionary Game Theoretical Approach

The utilization of coal-based solid waste materials (CSW) in road engineering is an important pathway for reducing stockpiling pressure, mitigating environmental risks, and promoting resource recycling. However, their large-scale diffusion is still constrained by residual engineering risk, misaligned cost and risk allocation between upstream and downstream actors, and imperfect regulatory and incentive mechanisms. To address these issues, this study develops a tripartite evolutionary game model involving the regulator, the waste producer, and the waste utilizer. The model incorporates pretreatment investment, residual engineering risk, government rewards and penalties, and green collaborative benefits to examine the evolutionary dynamics of the three parties and the stability of the system under different conditions. The results show that deep pretreatment by waste producers is a key prerequisite for the diffusion of CSW materials, as it reduces material instability and downstream engineering risk and increases the utilizer’s willingness to adopt such materials. The effects of rewards and penalties are differentiated across actors: effective penalties play a stronger role in constraining low-cost disposal by waste producers, whereas rewards are more effective in encouraging adoption by waste utilizers. The interaction analysis further shows that residual engineering risk significantly constrains the positive effect of green collaborative benefits, indicating that benefit enhancement cannot substitute for risk governance. In addition, the total amount of green collaborative benefits and their release and distribution structure jointly affect behavioral convergence and system stability. The system is more likely to evolve toward a stable state characterized by deep pretreatment, active adoption, and routine regulation when benefit sharing is consistent with the costs and risks borne by each party. Based on these findings, this study suggests that differentiated policy design is needed, including stronger source pretreatment and quality control, a coordinated reward–penalty mechanism for different actors, more targeted incentives and acceptance requirements for waste utilizers, and an improved governance framework featuring quality standards, full-process traceability, and risk warning mechanisms. These measures are essential for promoting the stable and large-scale utilization of CSW materials in road engineering. By translating model results into staged regulatory, quality-control, and supply-chain actions, the findings also support broader sustainable development goals, including responsible consumption and production, resilient infrastructure, climate action, and ecosystem protection.