The program supports a number of different types of culverts for use as control structures. They include circular concrete, circular cmp, pipe arch, elliptical and box shapes. The procedure for inlet and outlet control computations for all support culverts come from Hydraulic Design of Highway Culverts (HDS-5).
Standard shapes for pipe arch culverts are taken from Modern Sewer Design, American Iron and Steel Institute, Third Edition, 1995. Standard sizes for concrete elliptical shapes are taken from Concrete Pipe Design Manual, American Concrete Pipe Association, November 1992.
Figure 15: Culvert Logic Diagram
The above flow diagram is used to evaluate the flow conditions for each culvert based on the flow to be routed through it. In the case of an M1 or M2 condition, a direct step backwater computation is performed to determine impingement. The methodology for the direct step computation is outlined in Chow, Open Channel Hydraulics, 1959