This paper presents findings from a research study that evaluated the significance of soil structure interaction effects on culvert load rating. As a part of this research effort, three in-service culvert structures were instrumented and the load-response behavior monitored as two fully loaded dump trucks with known axle loads traversed the culverts. Concrete strength and stiffness corresponding to each culvert were obtained by taking concrete core samples and testing them in the laboratory. The surrounding soil envelop was characterized by drilling 3 exploratory boreholes at each site and by conducting five different test procedures. The load-response behavior of the culverts was then simulated using a 3 dimensional FE model. The material properties for concrete and surrounding soil were represented as statistical variables in the model. This approach that considered soil-structure interaction effects as well as inherent variability that exists in soil represented a more rational approach to culvert load rating.