During retesting, Richard Phillips, SDDOT Hydraulics Engineer, inspected a representative number of the new models and found them to accurately represent the box culvert inlets submitted for testing. The panel found the final report to be concise, understandable, the test models correctly built, and the experimentally determined inlet loss coefficients appear to be reasonable. The results indicate that the use of 30N flared wing walls, as on cast-in-place inlets, is slightly more hydraulically efficient than straight wing walls with beveled edges, as on precast culverts. Although the original questions in the problem statement were answered, this research has brought up new questions regarding the combined effects of varying barrel size and constant 4" bevel on loss coefficients. The Turner-Fairbank Highway Research Center may perform hydraulics testing on a continual basis, and may be suited to answer these new questions
The panel feels that this project may have been performed on schedule if at the outset we had met with the researcher in person and required that a work plan be written and evaluated by the panel. This may have been impractical, however, because the research was done by a graduate student focusing on many culvert designs, rather than specifically on SDDOTs inlet sections.