You are viewing an old version of this page. View the current version.

Compare with Current View Page History

« Previous Version 5 Next »

The following Manning’s n Roughness Coefficient table is from the United States Department of Transportation – Federal Highway Administration: Hydraulic Engineering website:

https://www.fhwa.dot.gov/engineering/hydraulics/library_listing.cfm




Table B.3. Manning's n Values for Closed Conduits.

Description

Manning's n Range

Concrete pipe

0.011–0.013

Corrugated metal pipe or pipe-arch:

Corrugated Metal Pipes and Boxes, Annular or Helical Pipe (Manning's n varies with barrel size)

68 by 13 mm (2-2/3 x 1/2 in.) corrugations

0.022-0.027

150 by 25 mm (6 x 1 in.) corrugations

0.022–0.025

125 by 25 mm (5 x 1in.) corrugations

0.025–0.026

75 by 25 mm (3 x 1 in) corrugations

0.027–0.028

150 by 50 mm (6 x 2 in.) structural plate corrugations

0.033–0.035

230 by 64 mm (9 x 2-1/2 in.) structural plate corrugations

0.033–0.037

Corrugated Metal Pipes Helical Corrugations, Full Circular Flow

68 by 13 mm (2-2/3 x 1/2 in.) corrugations

0.012–0.024

Spiral Rib Metal Pipe

Smooth walls

0.012–0.013

Vitrified clay pipe

0.012–0.014

Cast-iron pipe, uncoated

0.013

Steel pipe

0.009–0.013

Brick

0.014–0.017

Monolithic concrete:

1. Wood forms, rough

0.015–0.017

2. Wood forms, smooth

0.012–0.014

3. Steel forms

0.012–0.013

Cemented rubble masonry walls:

1. Concrete floor and top

0.017–0.022

2. Natural floor

0.019–0.025

Laminated treated wood

0.015–0.017

Vitrified clay liner plates

0.015