This report explores recommendations to revise the American Association of State Highway and Transportation Officials Load and Resistance Factor Design Bridge Design Specifications relating to the distribution of live load to buried structures. The report examines development of simplified design equations (SDEs) for structural response based on three-dimensional (3D) analysis of 830 buried culverts. In addition, the report suggests guidelines for conducting two-dimensional and 3D modeling for design situations with conditions not covered by the SDEs.