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Excessive moisture influences pavement performance by increasing surface deflection and decreasing bearing capacity. Seasonal fluctuation of groundwater, flooding, and spring thaw can all lead to changes in soil moisture and consequently stress states. Load restriction during and after inundation plays a key role in service life and maintenance planning of pavement systems. However, current procedures are either empirical or based on regional historical practices and do not incorporate transient and forecasted moisture profile in pavement response. This signifies the need for a mechanistic, coupled, and risk-based load restriction decision platform to assess pavement performance and determine traffic allowances during and after periods of excessive moisture. The research discussed in this report responds to this need by: (1) identifying key mechanical and environmental stressors and pavement characteristics through system dynamics modeling of hydrological regimes, moisture-dependent material properties, and pavement response models; and (2) developing a mechanistic load restriction decision toolkit validated against independent linear elastic models and field deflection measurement data. System-based univariate and multivariate sensitivity analysis demonstrated how different soil and climatic variables impact the moisture-dependent surface deflection and post-flooding recovery time. Inspired by the outcome of the system dynamics modeling, the first generation of PaveSafe, a flooded pavement assessment app, was prepared and is now available. It is a user-friendly application designed for different agent expertise and application in pavement sections with different model inputs. It is expected that the next generations of PaveSafe will be more computationally efficient, involve more material and modeling options, and be adaptable with other pavement performance packages.

The powerpoint presentation is a final deliverable. Project summary: "A methodology will be developed to characterize the vulnerability of state bridges, large culverts, and pipes to flooding. This effort will build upon the Flash Flood Vulnerability and Adaptation Assessment Pilot Project. That project, completing in 2014, scored bridges, large culverts, and pipes in MnDOT Districts 1 and 6 by their vulnerability to flooding so that detailed assessments of adaptation options for each facility could be prioritized. The current study aims to develop and test ways to enhance the vulnerability scoring techniques used and ensure their applicability throughout the state. The current project will not actually undertake the statewide assessment, just specify an approach that could be used for it. This project will also explore how the outputs of the analysis can be incorporated into the MnDOT's asset management systems. The results of this work will be a clear path forward for prioritizing adaptation actions - a key step towards enhancing agency resilience and maintaining good fiscal stewardship."

Minnesota’s climate is changing. Temperatures are on the rise and extreme precipitation events and associated flooding are becoming more frequent and severe. As the Earth continues to warm, these events are projected to become even more common since a warmer atmosphere is capable of holding more water vapor. Flooding presents a challenge to fulfilling the Minnesota Department of Transportation’s (MnDOT) mission to, “Plan, build, operate, and maintain a safe, accessible, efficient, and reliable multimodal transportation system..." When roads become inundated, the safety of motorists can be threatened, efficiency is reduced by the need to take detours, and system reliability is compromised. Recognizing this, MnDOT planners and engineers have long considered minimizing the risk of flash flooding in the siting and design of the state’s roadway network. However, as has been the standard practice worldwide, they have traditionally assumed that future climate conditions will be similar to those recorded in the past. Climate change challenges this assumption and calls for new approaches to understanding vulnerabilities across the highway system and at specific transportation facilities so that appropriate actions, adaptations, can be taken to minimize expanding risks. This project, one of 19 Federal Highway Administration (FHWA) climate vulnerability pilot studies nationwide looking at the effects of climate hazards on the transportation system, represents a starting point for developing these new approaches. The focus of this pilot study is on flash flooding risks to the highway system. While flooding is not the only threat to the state’s highway system posed by climate change,3 it is likely to be one of the most significant and has already caused extensive disruptions to the transportation system in many areas.