Links in SWMM5

Links

Links are the conveyance components of a drainage system and always lie between a pair of nodes. Types of links include:

·

Conduits

·

Pumps

·	Regulators

Conduits

Conduits are pipes or channels that move water from one node to another in the conveyance system. Their cross-sectional shapes can be selected from a variety of standard open and closed geometries. Irregular natural cross-section shapes are also supported, as are user-defined closed shapes.

The principal input parameters for conduits are:

·	names of the inlet and outlet nodes
·	offset height or elevation of the conduit above the inlet and outlet node inverts

·	conduit length
·	Manning's roughness

·	cross-sectional geometry
·	entrance/exit losses (optional)

·	seepage rate (optional)
·	presence of a flap gate to prevent reverse flow (optional)

·	inlet geometry code number if conduit acts as a culvert (optional).

Conduits designated as culverts are checked continuously during dynamic wave flow routing to see if they operate under Inlet Control as defined in the Federal Highway Administration's publication Hydraulic Design of Highway Culverts (Publication No. FHWA-NHI-01-020, May 2005).

See Also

Conduit Properties

Cross-Section Editor

Culvert Code Numbers

Conduit Properties
Name	User-assigned conduit name.
Inlet Node	Name of node on the inlet end of the conduit (which is normally the end at higher elevation).
Outlet Node	Name of node on the outlet end of the conduit (which is normally the end at lower elevation).
Description	Click the ellipsis button (or press Enter) to edit an optional description of the conduit.
Tag	Optional label used to categorize or classify the conduit.
Shape	Click the ellipsis button (or press Enter) to edit the geometric properties of the conduit's cross section.
Max. Depth	Maximum depth of the conduit's cross section (feet or meters).
Length	Conduit length (feet or meters).
Roughness	Manning's roughness coefficient. (Values for closed conduits) (Values for open channels)
Inlet Offset	Depth or elevation of the conduit invert above the node invert at the inlet end of the conduit (feet or meters).
Outlet Offset	Depth or elevation of the conduit invert above the node invert at the outlet end of the conduit (feet or meters).
Initial Flow	Initial flow in the conduit at the start of the simulation (flow units).
Maximum Flow	Maximum flow allowed in the conduit (flow units) - use 0 or leave blank if not applicable.
Entry Loss Coeff.	Head loss coefficient associated with energy losses at the entrance of the conduit. For culverts, refer to Culvert Inlet Loss Coefficientstable.
Exit Loss Coeff.	Head loss coefficient associated with energy losses at the exit of the conduit. For culverts, use a value of 1.0.
Avg. Loss Coeff.	Head loss coefficient associated with energy losses along the length of the conduit.
Flap Gate	YES if a flap gate exists that prevents backflow through the conduit, or NO if no flap gate exists.
Culvert Code	Code number of inlet geometry if conduit is a culvert subject to possible inlet flow control -- leave blank otherwise. Refer to the table of Culvert Code Numbers.

Shaping a Link

Links can be drawn as polylines containing any number of straight-line segments that define the alignment or curvature of the link. Once a link has been drawn on the Study Area Map, interior points that define these line segments can be added, deleted, and moved.

To edit the interior points of a link:

1.	Select the link to edit on the Map and put the map in Vertex Selection mode by either

·	clicking the button,
·	or selecting Edit >> Select Vertex from the Main Menu,

·	or right-clicking on the link and selecting Vertices from the popup menu.

2.	The mouse pointer will change shape to an arrow tip, and any existing vertex points on the link will be displayed as small open squares. The currently selected vertex will be displayed as a filled square.To select a particular vertex, click the mouse over it.

3.	To add a new vertex to the link, right-click the mouse and select Add Vertex from the popup menu (or simply press the <Insert> key on the keyboard).

4.	To delete the currently selected vertex, right click the mouse and select Delete Vertex from the popup menu (or simply press the <Delete> key on the keyboard).

5.	To move a vertex to another location, drag it with the left mouse button held down to its new position.

6.	While in Vertex Selection mode you can begin editing the vertices for another link by simply clicking on the link. To leave Vertex Selection mode, right click on the map and select Quit Editing from the popup menu, or simply select one of the other buttons on the Map Toolbar.

A link can also have its direction reversed (i.e., its end nodes switched) by right clicking on it and selecting Reverse from the pop-up menu that appears. Normally, links should be oriented so that the upstream end is at a higher elevation than the downstream end.

Weirs

Weirs, like orifices, are used to model outlet and diversion structures in a drainage system. Weirs are typically located in a manhole, along the side of a channel, or within a storage unit. They are internally represented in SWMM as a link connecting two nodes, where the weir itself is placed at the upstream node. A flap gate can be included to prevent backflow.

Five varieties of weirs are available, each incorporating a different formula for computing flow as a function of area, discharge coefficient and head difference across the weir:

·	Transverse (rectangular shape)
·	Side flow (rectangular shape)

·	V-notch (triangular shape)
·	Trapezoidal (trapezoidal shape)

·	Roadway (broad crested rectangular weir used to model roadway crossings).

Weirs can be used as storage unit outlets under all types of flow routing. If not attached to a storage unit, they can only be used in drainage networks that are analyzed with Dynamic Wave flow routing.

The height of the weir crest above the inlet node invert can be controlled dynamically through user-defined Control Rules. This feature can be used to model inflatable dams.

Weirs can either be allowed to surcharge or not. A surcharged weir will use an equivalent orifice equation to compute the flow through it. Weirs placed in open channels would normally not be allowed to surcharge while those placed in closed diversion structures or those used to represent storm drain inlet openings would be allowed to.

The principal input parameters for a weir include:

·	names of its inlet and outlet nodes
·	shape and geometry

·	crest height above the inlet node invert
·	discharge coefficient.

See Also

Weir Properties

Control Rules

Weir Properties
Name	User-assigned weir name.
Inlet Node	Name of node on inlet side of weir.
Outlet Node	Name of node on outlet side of weir.
Description	Click the ellipsis button (or press Enter) to edit an optional description of the weir.
Tag	Optional label used to categorize or classify the weir.
Type	Weir type: TRANSVERSE, SIDEFLOW, V-NOTCH, TRAPEZOIDAL or ROADWAY.
Height	Vertical height of weir opening (feet or meters)
Length	Horizontal length of weir opening (feet or meters)
Side Slope	Slope (width-to-height) of side walls for a V-NOTCH or TRAPEZOIDAL weir.
Inlet Offset	Depth or elevation of bottom of weir opening from invert of inlet node (feet or meters).
Discharge Coeff.	Discharge coefficient for flow through the central portion of the weir (for flow in CFS when using US units or CMS when using SI units). Typical values are: 3.33 US (1.84 SI) for sharp crested transverse weirs, 2.5 - 3.3 US (1.38 - 1.83 SI) for broad crested rectangular weirs, 2.4 - 2.8 US (1.35 - 1.55 SI) for V-notch (triangular) weirs. Discharge over Roadway weirs with a non-zero road width is computed using the FHWA HDS-5 method.
Flap Gate	YES if the weir has a flap gate that prevents backflow, NO if it does not.
End Coeff.	Discharge coefficient for flow through the triangular ends of a TRAPEZOIDAL weir. See the recommended values for V-notch weirs listed above.
End Contractions	Number of end contractions for a TRANSVERSE or SIDEFLOW weir whose length is shorter than the channel it is placed in. Either 0, 1, or 2 depending if no ends, one end, or both ends are beveled in from the side walls.
Can Surcharge	YES if the weir can surcharge (have an upstream water level higher than the height of the opening) or NO if it cannot.
Coeff. Curve	Name of an optional WEIR type curve that allows the central Discharge Coefficient to vary as a function of head (in feet or meters). Does not apply to Roadway weirs.
ROADWAY WEIR
Road Width	Width of roadway and shoulders (feet or meters)
Road Surface	Type of road surface: PAVED or GRAVEL.

Pumps

Pumps are links used to lift water to higher elevations. A pump curve describes the relation between a pump's flow rate and conditions at its inlet and outlet nodes. Five different types of pumps are supported:

Type1 An off-line pump with a wet well where flow increases incrementally with available wet well volume.
Type2 An in-line pump where flow increases incrementally with inlet node depth.
Type3 An in-line pump where flow varies continuously with head difference between the inlet and outlet nodes.
Type4 A variable speed in-line pump where flow varies continuously with inlet node depth.
Ideal An "ideal" transfer pump whose flow rate equals the inflow rate at its inlet node. No curve is required. The pump must be the only outflow link from its inlet node. Used mainly for preliminary design.

The on/off status of pumps can be controlled dynamically by specifying startup and shutoff water depths at the inlet node or through user-defined Control Rules. Rules can also be used to simulate variable speed drives that modulate pump flow.

The principal input parameters for a pump include:

·	names of the inlet and outlet nodes
·	name of its pump curve (or * for an Ideal pump)

·	initial on/off status
·	startup and shutoff depths.

See Also

Pump Properties

Control Rules

Pump Properties
Name	User-assigned pump name.
Inlet Node	Name of node on the inlet side of the pump.
Outlet Node	Name of node on the outlet side of the pump.
Description	Click the ellipsis button (or press Enter) to edit an optional description of the the pump.
Tag	Optional label used to categorize or classify the pump.
Pump Curve	Name of the Pump Curve which contains the pump's operating data (double-click to edit the curve). Enter * for an Ideal pump.
Initial Status	Status of the pump (ON or OFF) at the start of the simulation.
Startup Depth	Depth at inlet node when pump turns on (ft or m). Enter 0 if not applicable.
Shutoff Depth	Depth at inlet node when pump shuts off (ft or m). Enter 0 if not applicable.

Orifices

Orifices are used to model outlet and diversion structures in drainage systems which are typically openings in the wall of a manhole, storage facility, or control gate. They are internally represented in SWMM as a link connecting two nodes. An orifice can have either a circular or rectangular shape, be located either at the bottom or along the side of the upstream node, and have a flap gate to prevent backflow.

Orifices can be used as storage unit outlets under all types of flow routing. If not attached to a storage unit node, they can only be used in drainage networks that are analyzed with Dynamic Wave flow routing.

The flow through an orifice is computed based on the area of its opening, its discharge coefficient, and the head difference across the orifice.

The height of an orifice's opening can be controlled dynamically through user-defined Control Rules. This feature can be used to model gate openings and closings.

The principal input parameters for an orifice include:

·	names of its inlet and outlet nodes
·	configuration (bottom or side)

·	shape (circular or rectangular)
·	height above the inlet node invert

·	discharge coefficient
·	time to open or close.

See Also

Orifice Properties

Control Rules

Orifice Properties
Name	User-assigned orifice name.
Inlet Node	Name of node on the inlet side of the orifice.
Outlet Node	Name of node on the outlet side of the orifice.
Description	Click the ellipsis button (or press Enter) to edit an optional description of the orifice.
Tag	Optional label used to categorize or classify the orifice.
Type	Type of orifice (SIDE or BOTTOM).
Shape	Orifice shape (CIRCULAR or RECT_CLOSED).
Height	Height of orifice opening when fully open (feet or meters).Corresponds to the diameter of a circular orifice or the height of a rectangular orifice.
Width	Width of rectangular orifice when fully opened (feet or meters)
Inlet Offset	Depth or elevation of bottom of orifice above invert of inlet node (feet or meters).
Discharge Coeff.	Discharge coefficient (unitless). A typical value is 0.65.
Flap Gate	YES if a flap gate exists which prevents backflow through the orifice, or NO if no flap gate exists.
Time to Open/Close	The time to open a closed (or close an open) gated orifice in decimal hours. Use 0 or leave blank if timed openings/closings do not apply. Use Control Rules to adjust gate position.

Outlets

Outlets are flow control devices that are typically used to control outflows from storage units. They are used to model special head-discharge relationships that cannot be characterized by pumps, orifices, or weirs. Outlets are internally represented in SWMM as a link connecting two nodes. An outlet can also have a flap gate that restricts flow to only one direction.

Outlets attached to storage units are active under all types of flow routing. If not attached to a storage unit, they can only be used in drainage networks analyzed with Dynamic Wave flow routing.

A user-defined rating curve determines an outlet's discharge flow as a function of either the freeboard depth above the outlet's opening or the head difference across it. Control Rules can be used to dynamically adjust this flow when certain conditions exist.

The principal input parameters for an outlet include:

·	names of its inlet and outlet nodes
·	height above the inlet node invert

·	function or table containing its head (or depth) - discharge relationship.

See Also

Outlet Properties

Control Rules

Outlet Properties
Name	User-assigned outlet name.
Inlet Node	Name of node on inflow side of outlet.
Outlet Node	Name of node on discharge side of outlet.
Description	Click the ellipsis button (or press Enter) to edit an optional description of the outlet.
Tag	Optional label used to categorize or classify the outlet.
Inlet Offset	Depth or elevation of outlet above inlet node invert (ft or m).
Flap Gate	YES if a flap gate exists which prevents backflow through the outlet, or NO if no flap gate exists.
Rating Curve	Method of defining flow (Q) as a function of freeboard depth or head (y) across the outlet. FUNCTIONAL/DEPTH - uses a power function Q = AyB where y is the freeboard depth above the outlet's opening. FUNCTIONAL/HEAD - uses a power function Q = AyB where y is the head difference across the outlet. TABULAR/DEPTH - uses a tabulated curve of flow versus freeboard depth values. TABULAR/HEAD - uses a tabulated curve of flow versus head difference values.
FUNCTIONAL
- Coefficient	Coefficient (A) for the functional relationship between depth or head and flow rate.
- Exponent	Exponent (B) used for the functional relationship between depth or head and flow rate.
TABULAR
- Curve Name	Name of Rating Curve containing the relationship between depth or head and flow rate (double-click to edit the curve).

Cross-Section Editor

The Cross-Section Editor dialog is used to specify the shape and dimensions of a conduit's cross-section.

When a shape is selected from the image list an appropriate set of edit fields appears for describing the dimensions of that shape. Length dimensions are in units of feet for US units and meters for SI units. Slope values represent ratios of horizontal to vertical distance. The Barrels field specifies how many identical parallel conduits exist between its end nodes.

The Force Main shape option is a circular conduit that uses either the Hazen-Williams or Darcy-Weisbach formulas to compute friction losses for pressurized flow during Dynamic Wave flow routing. In this case the appropriate C-factor (for Hazen-Williams) or roughness height (for Darcy-Weisbach) is supplied as a cross-section property. The choice of friction loss equation is made on the Dynamic Wave Simulation Options dialog. Note that a conduit does not have to be assigned a Force Main shape for it to pressurize. Any of the other closed cross-section shapes can potentially pressurize and thus function as force mains using the Manning equation to compute friction losses.

If a Custom shaped section is chosen, a drop-down edit box will appear where you can enter or select the name of a Shape Curve that will be used to define the geometry of the section. This curve specifies how the width of the cross-section varies with height, where both width and height are scaled relative to the section's maximum depth. This allows the same shape curve to be used for conduits of differing sizes. Clicking the Edit button next to the shape curve box will bring up the Curve Editor where the shape curve's coordinates can be edited.

If an Irregular shaped section is chosen, a drop-down edit box will appear where you can enter or select the name of a Transect object that describes the cross-section's geometry. Clicking the Edit button next to the edit box will bring up the Transect Editor which allows you to edit the transect's data.

Transects

Transects refer to the geometric data that describe how bottom elevation varies with horizontal distance over the cross section of a natural channel or irregular-shaped conduit. The figure below displays an example of a transect for a natural channel.

Each transect must be given a unique name. Conduits refer to that name to represent their shape. A special Transect Editor is available for editing the station-elevation data of a transect. SWMM internally converts these data into tables of area, top width, and hydraulic radius versus channel depth. In addition, as shown in the diagram above, each transect can have a left and right overbank section whose Manning's roughness can be different from that of the main channel. This feature can provide more realistic estimates of channel conveyance under high flow conditions.

Transect Editor

The Transect Editor is invoked whenever a new Transect object is created or an existing Transect is selected for editing. It contains the following data entry fields:

Name

The name assigned to the transect.

Description

An optional comment or description of the transect.

Station/Elevation Data Grid

Values of distance from the left side of the channel along with the corresponding elevation of the channel bottom as one moves across the channel from left to right, looking in the downstream direction. The elevations can be relative to any reference point, such as the bottom of the channel, and not necessarily mean sea level. Up to 1500 data values can be entered.

Roughness

Values of Manning's roughness for the left overbank, right overbank, and main channel portion of the transect. The overbank roughness values can be zero if no overbank exists.

Bank Stations

The distance values appearing in the Station/Elevation grid that mark the end of the left overbank and the start of the right overbank. Use 0 to denote the absence of an overbank.

Modifiers

The Stations modifier is a factor by which the distance between each station will be multiplied when the transect data is processed by SWMM. Use a value of 0 if no such factor is needed.

The Elevations modifier is a constant value that will be added to each elevation value.

The Meander modifier is the ratio of the length of a meandering main channel to the length of the overbank area that surrounds it. This modifier is applied to all conduits that use this particular transect for their cross section. It assumes that the length supplied for these conduits is that of the longer main channel. SWMM will use the shorter overbank length in its calculations while increasing the main channel roughness to account for its longer length. The modifier is ignored if it is left blank or set to 0.

Right-clicking over the Data Grid will make a popup Edit menu appear. It contains commands to cut, copy, insert, and paste selected cells in the grid as well as options to insert or delete a row.

Clicking the View button will bring up a window that illustrates the shape of the transect cross section.

Culvert Code Numbers

Circular Concrete

1 Square edge with headwall

2 Groove end with headwall

3 Groove end projecting

Circular Corrugated Metal Pipe

4 Headwall

5 Mitered to slope

6 Projecting

Circular Pipe, Beveled Ring Entrance

7 45 deg. bevels

8 33.7 deg. bevels

Rectangular Box; Flared Wingwalls

9 30-75 deg. wingwall flares

10 90 or 15 deg. wingwall flares

11 0 deg. wingwall flares (straight sides)

Rectangular Box;Flared Wingwalls and Top Edge Bevel:

12 45 deg flare; 0.43D top edge bevel

13 18-33.7 deg. flare; 0.083D top edge bevel

Rectangular Box, 90-deg Headwall, Chamfered / Beveled Inlet Edges

14 chamfered 3/4-in.

15 beveled 1/2-in/ft at 45 deg (1:1)

16 beveled 1-in/ft at 33.7 deg (1:1.5)

Rectangular Box, Skewed Headwall, Chamfered / Beveled Inlet Edges

17 3/4" chamfered edge, 45 deg skewed headwall

18 3/4" chamfered edge, 30 deg skewed headwall

19 3/4" chamfered edge, 15 deg skewed headwall

20 45 deg beveled edge, 10-45 deg skewed headwall

Rectangular Box, Non-offset Flared Wingwalls, 3/4" Chamfer at Top of Inlet

21 45 deg (1:1) wingwall flare

22 8.4 deg (3:1) wingwall flare

23 18.4 deg (3:1) wingwall flare, 30 deg inlet skew

Rectangular Box, Offset Flared Wingwalls, Beveled Edge at Inlet Top

24 45 deg (1:1) flare, 0.042D top edge bevel

25 33.7 deg (1.5:1) flare, 0.083D top edge bevel

26 18.4 deg (3:1) flare, 0.083D top edge bevel

Corrugated Metal Box

27 90 deg headwall

28 Thick wall projecting

29 Thin wall projecting

Horizontal Ellipse Concrete

30 Square edge with headwall

31 Grooved end with headwall

32 Grooved end projecting

Vertical Ellipse Concrete

33 Square edge with headwall

34 Grooved end with headwall

35 Grooved end projecting

Pipe Arch, 18" Corner Radius, Corrugated Metal

36 90 deg headwall

37 Mitered to slope

38 Projecting

Pipe Arch, 18" Corner Radius, Corrugated Metal

39 Projecting

40 No bevels

41 33.7 deg bevels

Pipe Arch, 31" Corner Radius,Corrugated Metal

42 Projecting

43 No bevels

44 33.7 deg. bevels

Arch, Corrugated Metal

45 90 deg headwall

46 Mitered to slope

47 Thin wall projecting

Circular Culvert

48 Smooth tapered inlet throat

49 Rough tapered inlet throat

Elliptical Inlet Face

50 Tapered inlet, beveled edges

51 Tapered inlet, square edges

52 Tapered inlet, thin edge projecting

Rectangular

53 Tapered inlet throat

Rectangular Concrete

54 Side tapered, less favorable edges

55 Side tapered, more favorable edges

56 Slope tapered, less favorable edges

57 Slope tapered, more favorable edges

Culvert Inlet Loss Coefficients
Type of Structure and Design of Entrance	Coefficient
· Pipe, Concrete Projecting from fill, socket end (groove-end) Projecting from fill, sq. cut end Headwall or headwall and wingwalls: Socket end of pipe (groove-end) Square-edge Rounded (radius = D/12) Mitered to conform to fill slope *End-Section conforming to fill slope Beveled edges, 33.7 deg or 45 deg bevels Side- or slope-tapered inlet	0.2 0.5 0.2 0.5 0.2 0.7 0.5 0.2 0.2
· Pipe or Pipe-Arch, Corrugated Metal Projecting from fill (no headwall) Headwall or headwall and wingwalls square-edge Mitered to conform to fill slope, paved or unpaved slope *End-Section conforming to fill slope Beveled edges, 33.7 or 45 bevels Side- or slope-tapered inlet	0.9 0.5 0.7 0.5 0.2 0.2
· Box, Reinforced Concrete Headwall parallel to embankment (no wingwalls): Square-edged on 3 edges Rounded on 3 edges to radius of D/12 or B/12 or beveled edges on 3 sides Wingwalls at 30 deg to 75 deg to barrel: Square-edged at crown Crown edge rounded to radius of D/12 or beveled top edge Wingwall at 10 deg to 25 deg to barrel: Square-edged at crown Wingwalls parallel (extension of sides): Square-edged at crown Side- or slope-tapered inlet	0.5 0.2 0.4 0.2 0.5 0.7 0.2

*Note: "End Sections conforming to fill slope," made of either metal or concrete, are the sections commonly available from manufacturers. From limited hydraulic tests they are equivalent in operation to a headwall in both inlet and outlet control. Some end sections, incorporating a closed taper in their design have a superior hydraulic performance. These latter sections can be designed using the information given for the beveled inlet.

Source: Federal Highway Administration (2005). Hydraulic Design of Highway Culverts, Publication No. FHWA-NHI-01-020.

Standard Arch Pipe Sizes

Concrete Arch Pipes

Code	Rise (in)	Span (in)	Rise (mm)	Span (mm)
1	11	18	279	457
2	13.5	22	343	559
3	15.5	26	394	660
4	18	28.5	457	724
5	22.5	36.25	572	921
6	26.625	43.75	676	1111
7	31.3125	51.125	795	1299
8	36	58.5	914	1486
9	40	65	1016	1651
10	45	73	1143	1854
11	54	88	1372	2235
12	62	102	1575	2591
13	72	115	1829	2921
14	77.5	122	1969	3099
15	87.125	138	2213	3505
16	96.875	154	2461	3912
17	106.5	168.75	2705	4286

Corrugated Steel, 2-2/3 x 1/2" Corrugation

Code	Rise (in)	Span (in)	Rise (mm)	Span (mm)
18	13	17	330	432
19	15	21	381	533
20	18	24	457	610
21	20	28	508	711
22	24	35	610	889
23	29	42	737	1067
24	33	49	838	1245
25	38	57	965	1448
26	43	64	1092	1626
27	47	71	1194	1803
28	52	77	1321	1956
29	57	83	1448	2108

Corrugated Steel, 3 x 1" Corrugation

Code	Rise (in)	Span (in)	Rise (mm)	Span (mm)
30	31	40	787	1016
31	36	46	914	1168
32	41	53	1041	1346
33	46	60	1168	1524
34	51	66	1295	1676
35	55	73	1397	1854
36	59	81	1499	2057
37	63	87	1600	2210
38	67	95	1702	2413
39	71	103	1803	2616
40	75	112	1905	2845
41	79	117	2007	2972
42	83	128	2108	3251
43	87	137	2210	3480
44	91	142	2311	3607

Structural Plate, 18" Corner Radius

Code	Rise (in)	Span (in)	Rise (mm)	Span (mm)
45	55	73	1397	1854
46	57	76	1448	1930
47	59	81	1499	2057
48	61	84	1549	2134
49	63	87	1600	2210
50	65	92	1651	2337
51	67	95	1702	2413
52	69	98	1753	2489
53	71	103	1803	2616
54	73	106	1854	2692
55	75	112	1905	2845
56	77	114	1956	2896
57	79	117	2007	2972
58	81	123	2057	3124
59	83	128	2108	3251
60	85	131	2159	3327
61	87	137	2210	3480
62	89	139	2261	3531
63	91	142	2311	3607
64	93	148	2362	3759
65	95	150	2413	3810
66	97	152	2464	3861
67	100	154	2540	3912
68	101	161	2565	4089
69	103	167	2616	4242
70	105	169	2667	4293
71	107	171	2718	4343
72	109	178	2769	4521
73	111	184	2819	4674
74	113	186	2870	4724
75	115	188	2921	4775
76	118	190	2997	4826
77	119	197	3023	5004
78	121	199	3073	5055

Structural Plate, 31" Corner Radius

Code	Rise (in)	Span (in)	Rise (mm)	Span (mm)
79	112	159	2845	4039
80	114	162	2896	4115
81	116	168	2946	4267
82	118	170	2997	4318
83	120	173	3048	4394
84	122	179	3099	4547
85	124	184	3150	4674
86	126	187	3200	4750
87	128	190	3251	4826
88	130	195	3302	4953
89	132	198	3353	5029
90	134	204	3404	5182
91	136	206	3454	5232
92	138	209	3505	5309
93	140	215	3556	5461
94	142	217	3607	5512
95	144	223	3658	5664
96	146	225	3708	5715
97	148	231	3759	5867
98	150	234	3810	5944
99	152	236	3861	5994
100	154	239	3912	6071
101	156	245	3962	6223
102	158	247	4013	6274

Source: Modern Sewer Design (Fourth Edition), American Iron and Steel Institute, Washington, DC, 1999.

Standard Elliptical Pipe Sizes
Code	Minor Axis (in)	Major Axis (in)	Minor Axis (mm)	Major Axis (mm)
1	14	23	356	584
2	19	30	483	762
3	22	34	559	864
4	24	38	610	965
5	27	42	686	1067
6	29	45	737	1143
7	32	49	813	1245
8	34	53	864	1346
9	38	60	965	1524
10	43	68	1092	1727
11	48	76	1219	1930
12	53	83	1346	2108
13	58	91	1473	2311
14	63	98	1600	2489
15	68	106	1727	2692
16	72	113	1829	2870
17	77	121	1956	3073
18	82	128	2083	3251
19	87	136	2210	3454
20	92	143	2337	3632
21	97	151	2464	3835
22	106	166	2692	4216
23	116	180	2946	4572

Note: The Minor Axis is the maximum width for a vertical ellipse and the full depth for a horizontal ellipse while the Major Axis is the maximum width for a horizontal ellipse and the full depth for a vertical ellipse.

Source: Concrete Pipe Design Manual, American Concrete Pipe Association, 2011 (www.concrete-pipe.org).

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