The current analysis programs, used for sizing box culvert structures (HY-8 and others), do not analyze multiple barrel box culverts correctly. These programs model multiple barrel structures as though each barrel is a separate single box with it's own wing walls, instead of as a multiple barreled section with one set of common wing walls (as is the actual condition for most CIP box culverts). In order for the department to assure optimized box culvert design, it is necessary to determine the effects of the various inlet conditions and box configurations that are used in South Dakota .
Title: Effects of Inlet Geometry on Flow Capacity of Single and Multiple Barrel Box Culverts
Project Researcher: Sterling Jones, TFHRC.
Project Manager: Paul Oien
Research Period: 8/2/2002 - 6/30/2003
Problem Statement: Each year the South Dakota Department of Transportation designs and builds many cast-in-place (CIP) and precast box culvert structures that allow drainage to pass under our roadways. The CIP boxes typically have 30-degree flared wing walls and the precast have straight wing walls with 4-inch bevel on the inside edges of the wing walls and top slab. Previous research, SD93-12, conducted on a limited number of single barrel box culverts, indicated that further research was necessary to determine the effects of multiple barrel structures, loss coefficients of unsubmerged outlets, and to determine the effect of 12 inch corner fillets versus 6 inch corner fillets. In order to optimize the design of both types of box culverts it is also necessary to determine the effects of span to rise ratio, skewed end condition, and optimum edge condition on typical box culvert installations.