Standard Arch Pipe Dimensions Dimensions of Arch Pipe Round EquivalentRiseSpan 151118 181322 241829 302236 36 2743 42 3050 48 3658 54 4065 60 4472 725981 Dimensions in Inches Related Articles Standard Elliptical Pipe Dimensions Runoff Coefficients (C) Programmed Pipe Sizes Manning’s n-values