PLANNING FOR RESILIENT ROADS Approaches to Account for Climate Change Impacts on Flexible Pavement Design and Rehabilitation Practices By NAPA As the climate changes, extreme weather events can impact the performance and resiliency of flexible pavement systems. Traditional pavement design relies on historical (stationary) climate data to design and predict future pavement performance, thus changing climate may lead to under-designed pavements and constrained budgets for maintenance and rehabilitation (M&R). There are three common approaches to incorporate climate change impacts into the decision-making process to help design, build and maintain resilient pavements. The three approaches include scenario-based (top-down), asset-based (bottom-up) and hybrid (a combination of both). Regardless of which approach is selected, stakeholder involvement and incorporating future climate projections into the analysis are crucial steps. A scenario-based approach begins with choosing two or more future climate change scenarios. This approach can be useful in identifying potential future pavement-life reductions and promoting climate resilience through enhanced pavement design. In comparison, the asset-based approach seeks to evaluate the pavement’s sensitivity to plausible future climate or environmental conditions while designing for future traffic loads. A key difference between the two approaches is that the asset-based approach provides a more complete picture of the pavement’s response to incremental environmental change, and the scenario-based approach provides information on the timing of critical environmental change to inform design and M&R. The hybrid approach is when an asset’s response to incremental environmental changes is investigated first and then the timing of critical pavement impacts for budgeting and planning purposes is predicted. A case study example of the hybrid adaptation approach was performed for a regional connector in coastal New Hampshire (Knott et al., 2019). First, the pavement’s response to loading with incremental temperature and groundwater rise is investigated using pavement climate sensitivity catalogs. A climate sensitivity catalog is a tool to assess an asset’s response to incremental changes in two or three climate parameters like temperature and groundwater levels, or temperature and precipitation, etc. For example, in this case study, pavement performance was explored as a function of incremental changes in temperature on one axis and incremental changes in groundwater levels on the other axis. 28
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