Project-based sustainable timing series decision-making for pavement maintenance using multi-objective optimization: An innovation in traditional solutions

Pavement maintenance timing series (PMTS) optimization at the project level should consider multiple interventional maintenance impacts within the planning horizon, while making trade-offs between investment and environmental burden, which is difficult to address with traditional methods, partly due to the lack of understanding of the interaction mechanism between the sustainable objectives. To bridge this gap, this paper presents a customized project-based PTMS decision-making method using multi-objective optimization, and applied it to explore the PMTS generation mechanisms by decomposing the sustainable objectives. Results show that among the three sustainable objectives, life-cycle agency cost and greenhouse gas (GHG) emissions drive the timing series formation of maintenance technologies, and GHG emissions can also limit the "greedy" growth of non-zero decision variables, while the integral function form of the benefit of pavement maintenance can improve the lowest performance condition. In addition, the proposed approach allows for the maximization of the trade-offs between the three sustainable objectives using the Euclidean norm strategy, while providing a prioritized set of potential PMTS solutions. Based on that, a benefit-to-cost & GHG emissions ratio model (BCGRM) was proposed to compare with the above tri-objective optimization model in generating PMTS. Since the non-dominating nature of the three objectives cannot be directly considered, BCGRM will get higher investment benefits by increasing the maintenance frequency.