Channel

Attachment

The attachment point is located above the midpoint of the bottom width, at a height equal to the Depth parameter.

Input Parameters

Note: All dimensions are in meters or feet unless otherwise noted. All slopes are in run-over-rise form (for example, 4 : 1), unless indicated as a percent slope with a “%” sign.

Parameter	Description	Type	Default
Depth	The vertical offset down from the profile grade line elevation to the bottom of the channel.	Numeric, Positive	2.0 m 6.0 ft
Bottom Width	Width of bottom of the channel.	Numeric, Positive	2.0 m 6.0 ft
Sideslope	Channel sideslopes	Numeric	1 (:1)
Lining Depth	Depth of channel lining. The Lining Depth is measured perpendicular to the side of the slope, as shown in the previous diagram.	Numeric, Positive	0.1m 0.33ft
Left Marked Point	Optional marked point on the outermost channel point on the left side; If no code is entered then marked point is not inserted.	String
Right Marked Point	Optional marked point on the outermost channel point on the right side; If no code is entered then marked point is not inserted.	String
Left Extension Height	Extension of channel left side over the insertion point	Numeric, Positive	0.5m 1.67ft
Left Backslope Width	Channel backfill width on left side	Numeric, Positive	1.5 m 5.0 ft
Left Backslope	Channel backfill slope on left side	Numeric	4 (:1)
Right Extension Height	Extension of channel right side over the insertion point	Numeric, Positive	0.5 m 1.67 ft
Right Backslope Width	Channel backfill width on the right side	Numeric, Positive	1.5 m 5.0 ft
Right Backslope	Channel backfill slope on right side	Numeric	4 (:1)

Target Parameters

This section lists the parameters in this subassembly that can be mapped to one or more target objects. For more information, see To Specify Corridor Targets.

Parameter	Description	Status
Left Extension Height	May be used to override the fixed extension height on left side and tie to a profile. The following object types can be used as targets for specifying the elevation: profiles, 3D polylines, feature lines, or survey figures.	Optional
Left Backslope Width	May be used to override the fixed Left Backslope Width and tie to an offset alignment. The following object types can be used as targets for specifying the width: alignments, polylines, feature lines, or survey figures.	Optional
Left Backslope Elevation	May be used to override the fixed Left Backslope and tie to a profile. The following object types can be used as targets for specifying the elevation: profiles, 3D polylines, feature lines, or survey figures.	Optional
Right Extension Height	May be used to override the fixed extension height on right side and tie to a profile. The following object types can be used as targets for specifying this: profiles, 3D polylines, feature lines, or survey figures.	Optional
Left Backslope Width	May be used to override the fixed Right Backslope Width and tie to an offset alignment. The following object types can be used as targets for specifying the width: alignments, polylines, feature lines, or survey figures.	Optional
Left Backslope Elevation	May be used to override the fixed Right Backslope and tie to a profile. The following object types can be used as targets for specifying this: profiles, 3D polylines, feature lines, or survey figures.	Optional

Output Parameters

None.

Behavior

This subassembly builds an open channel shape using the input parameters. The attachment point is typically at the start of the baseline, at associated alignments and profiles. The bottom link of the channel is then drawn using a specified width. Using the sideslope parameter, the channel sides are drawn on either sides.

For the channel lining depth, if a non-zero positive value is specified for the Lining Depth parameter, then a material lining is drawn around the channel. The Lining Depth is measured perpendicular to the side of the slope, as shown in the previous diagram. If a zero value is specified for the Lining Depth, then no links are inserted.

Similarly, if a zero value is specified for left or right extensions and backslope widths, those links are omitted, or are not drawn. Extension height can be controlled with a target parameter profile association. Similarly, the height of the backslope end point can be specified to a profile. To force the outer backslope point to the channel top elevation, associate this point to the channel’s finish grade profile, to which this assembly is attached.

If the Backslope Width is omitted, the Right Marked Point is located on the outer point of channel height extension. If the Channel Height Extension link is also omitted, then the marked point is located on the outermost point on the channel top.

Note:

In Autodesk Civil 3D 2010 and previous versions, the Lining Depth parameter was measured vertically. In Autodesk Civil 3D 2011 and later, this parameter is measured perpendicular to the side slope. Therefore, if you open a drawing containing these subassemblies that was created in Autodesk Civil 3D 2010 or prior in Autodesk Civil 3D 2011 or later, and then rebuild the corridor(s), this parameter will be changed to reflect the new behavior. Any volume reports that use this subassembly will be updated to reflect the new behavior.

Layout Mode Operation

In layout mode, this subassembly draws as it is defined using the input parameters, starting from the attachment point.

Point, Link, and Shape Codes

The following table lists the point, link, and shape codes for this subassembly that have codes assigned to them. Point, link, or shape codes for this subassembly that do not have codes assigned are not included in this table.

Point/Link	Codes	Description
P1	Channel_Flowline	Middle point of the channel bottom
P2,P3	Channel_Bottom
P4, P5	Channel_Top
P6,P7	Channel_Extension
P8,P9	Channel_Backslope
P13
L1, L2, L3	Datum, Channel_Bottom and Top (if lining is NOT used)
L4 to L7	Datum, Top
L8 to L12	Channel_Bottom and TOP (if lining IS used)
S1	Lining_Material	Channel Lining Material