This study addresses challenges that arise during highway embankment construction on road widening projects when additional fill is placed above existing culverts. Researchers conducted reduced-scale model laboratory tests to simulate culvert behavior under different loading conditions and to determine how well lightweight materials (LWMs) perform when subjected to changing loads. Testing showed that proximity of LWM to the culvert’s top surface strongly influences the magnitude of strain reductions or increases. Placing LWMs with relatively low elastic modulus closer to the culvert’s top surface led to reduced culvert ceiling strain and increased culvert wall strain. LWMs with relatively high elastic modulus generally increased both culvert ceiling and wall strain. Researchers conducted over 12,000 numerical simulations to analyze culvert behavior under a range of loading conditions involving LWMs. Simulations underwrote the development of empirical formulas that can be used by practitioners to design LWM installation profiles above culverts. Following the development of empirical formulas, researchers developed a user-friendly web app practitioners can use to efficiently identify the best LWM installation profile for individual projects. Adopting the insights, methodologies, and tools presented in this study will enhance infrastructure resilience and sustainability on highway widening projects.

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