Assessment of Simplified Rating Factor Methodology for Shallow Cover Metal Culverts

Culverts under existing roadways that do not meet current design and construction cover requirements are common. Even though they may have performed without any issues for decades, rating many of them using today’s specifications and methodologies will result in a score that represents insufficiency, thus requiring the owner to replace or post the culvert. While advanced analyses, such as nonlinear finite element modeling and load testing, can be used to rate culverts with better accuracy than typical simplified calculations, those approaches are costly and require a high level of expertise. Therefore, simplified approaches to load rating shallow buried corrugated metal culverts that emphasize the available resistance of the structure rather than automatically rendering a rating that defines the structure as insufficient when the design cover requirement is not satisfied are developed and assessed herein. The accuracy and applicability of the methodology are demonstrated using finite element results from a two-dimensional finite element software developed specifically for culvert analysis and design.