The Urban Conduit Link
    • 23 Oct 2022
    • 4 Minutes to read

    The Urban Conduit Link


    Article summary

    Conduit links represent the pipes themselves connecting the nodes in your urban system.

    UrbanNodesimagesurbanconduit.PNG

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    Rules of Conduit links

    If using Steady or Kinematic Wave routing, only a single outflow Conduit link is allowed from an Urban Junction Node. Multiple Conduit links can be conected to a Junction node if using Dynamic Wave routing.

    Exactly two outflow Conduit links must be connected from an Urban Divider Node.

    Only one (inflow) Conduit link can be connected to an Urban Outfall Node.

    If using Kinematic Wave routing, Conduit links are the only link type allowed, aside from the outflow link from an Urban Storage Node.


    Conduit label/name

    The Conduit node name by default will be provided by parameters setup in the Urban Model Defaults menu.


    Optional descriptors

    Description

    This field allows for an optional text description. The field will be blank by default.

    Tag

    This field allows for an optional text tag, to allow you to categorise units. The field will be blank by default.


    Shape/Depth

    Fields are provided for the Shape and Max. Depth of the Conduit. By default, these are based on values set on the Model Defaults window.

    The 3 dots to the right of the Shape field enable access to the Cross-Section Editor window, from which a conduit shape, maximum depth, and number of barrels (identical, parallel pipes) can be specified. The maximum depth specified here will automatically populate the Max. Depth field in the conduit properties window.


    Length

    The conduit Length is required. This will be set by default to the value set in the Model Defaults window.

    The Length will be automatically calculated from the length of the line drawn on the map if the default length is set to zero in the Model Defaults window. This length is only calculated at the point of the link being drawn (already drawn links must be deleted and re-drawn for the length to be calculated from the map).


    Roughness

    The conduit Roughness is required. This will be set by default to the value set in the Model Defaults window.


    Additional Parameters

    Inlet Offset

    Conduit links can have an offset specified at the inflow and outflow ends. This is the distance from the invert level of the inflow node. The value may be as a depth or elevations, as specified by the Offset convention set in the Model Defaults window.

    Outlet Offset

    Conduit links can have an offset specified at the inflow and outflow ends. This is the distance from the invert level of the outflow node. The value may be as a depth or elevations, as specified by the Offset convention set in the Model Defaults window.

    Maximum Flow

    The Conduit maximum flow. This can be left blank if not applicable.

    Entry Loss Coeff.

    This field specifies the head loss coefficient associated with energy losses at the entrance of the conduit. We refer the user to the EPA Manual for further details.

    Exit Loss Coeff.

    This field specifies the head loss coefficient associated with energy losses at the exit of the conduit. We refer the user to the EPA Manual for further details.

    Avg. Loss Coeff.

    This field specifies the head loss coefficient associated with energy losses along the length of the conduit.


    Flap Gate

    A Flap Gate can be specified so prevent backflow. This option will be set to NO by default.


    Culvert Code

    If a Culvert Inlet Geometry code number is assigned to a conduit, it will act as a culvert. This should be used only for conduits that act as culverts and should be analysed for inlet control conditions using the FHWA HDS-5 method. These code numbers are listed in below.

    TypeDescriptionCode
    Circular ConcreteSquare edge with headwall
    Groove end with headwall
    Groove end projecting
    1
    2
    3
    Circular Corrugated Metal PipeHeadwall
    Mitered to slope
    Projecting
    4
    5
    6
    Circular Pipe, Beveled Ring Entrance45 deg. bevels
    33.7 deg. bevels
    7
    8
    Rectangular Box; Flared Wingwalls30-75 deg. wingwall flares
    90 or 15 deg. wingwall flares
    0 deg. wingwall flares (straight sides)
    9
    10
    11
    Rectangular Box;Flared Wingwalls and Top Edge Bevel:45 deg flare; 0.43D top edge bevel
    18-33.7 deg. flare; 0.083D top edge bevel
    12
    13
    Rectangular Box, 90-deg Headwall, Chamfered / Beveled Inlet Edgeschamfered 3/4-in.
    beveled 1/2-in/ft at 45 deg (1:1)
    beveled 1-in/ft at 33.7 deg (1:1.5)
    14
    15
    16
    Rectangular Box, Skewed Headwall, Chamfered / Beveled Inlet Edges3/4" chamfered edge, 45 deg skewed headwall
    3/4" chamfered edge, 30 deg skewed headwall
    3/4" chamfered edge, 15 deg skewed headwall
    45 deg beveled edge, 10-45 deg skewed headwall
    17
    18
    19
    20
    Rectangular Box, Non-offset Flared Wingwalls, 3/4" Chamfer at Top of Inlet45 deg (1:1) wingwall flare
    8.4 deg (3:1) wingwall flare
    18.4 deg (3:1) wingwall flare, 30 deg inlet skew
    21
    22
    23
    Rectangular Box, Offset Flared Wingwalls, Beveled Edge at Inlet Top45 deg (1:1) flare, 0.042D top edge bevel
    33.7 deg (1.5:1) flare, 0.083D top edge bevel
    18.4 deg (3:1) flare, 0.083D top edge bevel
    24
    25
    26
    Corrugated Metal Box90 deg headwall
    Thick wall projecting
    Thin wall projecting
    27
    28
    29
    Horizontal Ellipse ConcreteSquare edge with headwall
    Grooved end with headwall
    Grooved end projecting
    30
    31
    32
    Vertical Ellipse ConcreteSquare edge with headwall
    Grooved end with headwall
    Grooved end projecting
    33
    34
    35
    Pipe Arch, 18" Corner Radius, Corrugated Metal90 deg headwall
    Mitered to slope
    Projecting
    36
    37
    38
    Pipe Arch, 18" Corner Radius, Corrugated MetalProjecting
    No bevels
    33.7 deg bevels
    39
    40
    41
    Pipe Arch, 31" Corner Radius,Corrugated MetalProjecting
    No bevels
    33.7 deg. bevels
    42
    43
    44
    Arch, Corrugated Metal90 deg headwall
    Mitered to slope
    Thin wall Projecting
    45
    46
    47
    Circular CulvertSmooth tapered inlet throat
    Rough tapered inlet throat
    48
    49
    Elliptical Inlet FaceTapered inlet, beveled edges
    Tapered inlet, square edges
    Tapered inlet, thin edge projecting
    50
    51
    52
    RectangularTapered inlet throat53
    Rectangular ConcreteSide tapered, less favorable edges
    Side tapered, more favorable edges
    Slope tapered, less favorable edges
    Slope tapered, more favorable edges
    54
    55
    56
    57

    We refer the user to the EPA Manual for further details, where the following is stated. 

    Culvert conduits 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 Third Edition (Publication No. FHWA-HIF-12-026, April 2012). Under inlet control a culvert obeys a particular flow versus inlet depth rating curve whose shape depends on the culvert’s shape, size, slope, and inlet geometry.


    Equations

    The 1D urban solver uses the Manning equation to express the relationship between cross-sectional area, hydraulic radius, slope and flow rate in all conduits. We refer the user to the EPA Manual for further details.


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