Greenhouse gas emissions have caused global temperatures to rise since the mid-20th century accompanied by sea-level rise (SLR). Temperature increases and SLR-induced groundwater rise have been shown to cause premature pavement failure in many roadway structures. Hybrid bottom-up/top-down (hybrid) adaptation approaches have shown promise by initially investigating an asset’s response to incremental environmental change and then identifying the timing of critical effects for budgetary planning. This improves practitioners’ understanding of the asset’s climate resiliency and informs adaptation-plan development to minimize both cost and risk. In this study, a hybrid approach to pavement adaptation with climate-change-induced temperature and groundwater rise is demonstrated at a case-study site in coastal New Hampshire. The hot-mix-asphalt (HMA) thickness that achieves a minimum of 85% reliability is calculated for 70 combinations of incremental temperature and groundwater rise. Increasing the base-layer thickness improves resiliency against rising temperatures, but rising groundwater diminishes this improvement demonstrating that both HMA and base-layer thickness increases are needed. Thirteen adaptation pathways are evaluated for pavement performance, life-cycle costs, and road-surface inundation over a 60-year pavement management period. A stepwise and flexible adaptation plan is developed that includes HMA overlays with prescribed thickness and application timing, base-layer rehabilitation options, and re-evaluation opportunities.

Climate change poses a threat to the performance and resiliency of flexible pavement systems around the world and can lead to inadequate designs or shortened service life which, in turn, tax the already limited budgets of transportation agencies and increase user costs. This paper aims to provide a high-level overview of three common approaches (scenario-based, asset-based and hybrid) that can be used to incorporate climate change in pavement design and rehabilitation practices. Examples of each approach for a flexible pavement system are presented along with a discussion of their advantages and limitations. Additionally, select results from a pavement life cycle assessment (LCA) case-study comparing the use of simulated future climate projections instead of historical observed climate data is included to demonstrate impacts on maintenance and rehabilitation budgeting and planning. Current knowledge gaps and research needs are identified and discussed to promote future collaboration towards designing and maintaining more resilient flexible pavements under a changing climate.