Roughness Coefficients
The following table provides roughness coefficients for conduits.
Type of Conduit | n-Value |
Concrete Box | 0.012 |
Concrete Pipe | 0.012 |
Smooth-lined metal pipe | 0.012 |
Smooth lined plastic pipe | 0.012 |
Corrugated metal pipe | 0.015-0.027 |
Structural plate pipe | 0.027-0.036 |
Long span structural plate | 0.031 |
Corrugated metal (paved interior) | 0.012 |
Plastic | 0.012-0.024 |