Actual Bridge Section Manning Roughness

This is the Manning roughness n value of the left overbank, channel or the right overbank of the actual bridge section. These values can be imported from the HECRAS studies where they were used in the discharge distribution calculations. They are not used in the scour computations for the Maryland ABSCOUR method or the NCHRP 24-20 method; however, these "n" values are used in the computation of the contraction scour for the HEC-18 method "Ultimate Contraction Scour for Cohesive Soil".