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South Dakota Department of Transportation
Project Synopsis
SD2002-04


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
Status:
Cost: $75,138.00

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.

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 .



Findings:
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
Status:
Cost: $75,138.00

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.

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 .



Findings:

Research Objectives:
1  Determine optimum edge condition for wing walls.
2  Determine the effects of inlet geometry on flow capacity of single and multiple barrel culverts with optimized edge treatment of wing walls.
3  Determine effects of span to rise ratio on flow capacity with various inlet geometries.
4  Determine the effects of skew on flow capacity of box culverts.

Research Tasks:
1  Review previous and ongoing research and present findings to the technical panel.
2  Meet with the project’s technical panel to review project scope and work plan.
3  Develop a test matrix listing sizes and configurations of box culverts to be tested. Not all sizes need to be tested, but a sufficient number must be tested to allow correlation of data from models tested to sizes not tested. The following parameter
4  Technical panel will approve testing matrix before models are made or testing begins.
5  Construct accurate detailed scale models of box culverts from construction plans furnished by SDDOT.
6  Test models identified in test matrix to determine hydraulic flow capacity.
7  Test data should be compiled and recommendations provided on applicability of using this data to update modeling programs such as HY-8 and other software applications.
8  Prepare preliminary draft report for review by technical panel. This preliminary report will show how to incorporate test results into hand calculations as well as software applications, used to do hydraulic analysis.
9  Prepare a final report, after receiving comments from technical panel on draft report, and executive summary of the research methodology, findings, conclusions, and recommendations.
10  Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.

Documents Available:
SD2002_04_Final_Report.pdf

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