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Inference Rules - Pipe Parameters (Collection)

Missing data values can be inferred from existing data, allowing gaps in data to be filled in with reasonable values.

Inference data is edited on the Inference Data Editor.

The following can be inferred for pipes:

Parameter

Inferred From

Upstream / Downstream Invert Level

There are five methods by which invert level can be inferred:

Invert from Cover Level

Pipe US Invert Level and DS Invert Level values are inferred from connected node Cover Level values:

US Invert Level

=

US Node Cover Level

-

Pipe US Depth from Cover

DS Invert Level

=

DS Node Cover Level

-

Pipe DS Depth from Cover

If either the node Cover Level or pipe Depth from Cover are not defined, inference will not be carried out.

Invert from Lowest Soffit

Pipe US Invert Level and DS Invert Level values are inferred from the lowest soffit level of pipes connected to the node at which the pipe invert level is missing.

  • Incoming Pipes:

DS Invert Level

=

Lowest Soffit of outgoing pipes

-

Pipe DS Height

  • Outgoing Pipes

US Invert Level

=

Lowest Soffit of incoming pipes

-

Pipe US Height

See the Invert from Lowest Soffit section below for further details.

Invert from Gradients

Pipe US Invert Level and DS Invert Level values, for a pipe with one missing invert level, are inferred from the pipe's known invert level and the shallowest gradient of connecting pipes.

US Invert Level

=

DS Invert Level

+

ΔH

DS Invert Level

=

US Invert Level

-

ΔH

Where ΔH = Shallowest gradient of connected pipes multiplied by length of pipe to be inferred.

See the Invert from Gradients section below for further details.

Invert from Lateral Connection

The invert level at a lateral connection is inferred from invert levels of the pipe to which it is attached, and the ratio of the distances of the lateral connection from the upstream and downstream nodes of the main pipe.

See the Invert from Lateral Connection section below for an example.

Invert Interpolate from Inverts

The invert level of a pipe is inferred by linear interpolation between known upstream and downstream inverts.

See the Interpolate from Inverts section below for an example.

Length

Pipe Length is inferred from pipe geometry (coordinates of connected nodes and bend locations).

  • If the coordinates of a connected node are not defined, a location of (0,0) will be assumed.
  • If an US Invert Leveland DS Invert Level for the pipe are defined, the Gradient of the pipe will also be calculated and flagged with the Inference flag, (if set).

Gradient

Gradient is calculated as:

Pipes must have an US Invert Level, DS Invert Level and Length> 0 for inference to be carried out.

System Type

Pipe System Type is inferred from connected node System Type values.

Pipe System Type = US node System Type = DS node System Type

The System Type of upstream and downstream nodes must be identical for a value to be inferred.

Size and Shape

Height, Width and Shape can be inferred from upstream and downstream pipes. Shape will only be inferred if the Infer Shape parameter is checked in the Inference Editor.

If an upstream or downstream size or shape value of a pipe is missing, the missing value is inferred from:

  • Known Height, Width or Shape at upstream / downstream end of pipe if available.
  • If neither end of the pipe has a known value, InfoAsset Manager searches upstream from the pipe until a value is found or until a branch in the network is found. If a value is found, the missing pipe values will be inferred from this upstream value.
  • If an upstream value is not found, InfoAsset Managersearches downstream from the pipe until a value is found or until a branch in the network is found. If a value is found, the missing pipe values will be inferred from this downstream value.
  • If no values are found, inference will not be carried out.

Start and End Nodes

Use the Add manhole if node does not exist rule, to add nodes to the nodeless ends of pipes.

A node of type manhole will be created at the end of pipes with an US Node ID or DS Node ID (that is not a reserved node name) where the node does not exist in the network.

Invert from Lowest Soffit

Missing Pipe Invert Level values are inferred from the lowest soffit level of incoming pipes connected to the node at which the pipe invert level is missing.

Tip:

When inferring invert values for a selection, select the Node attached to the pipe for which the value is to be inferred.

For each (selected) node in the network:

  1. The soffit level of Incoming Pipes with a known Height and Invert level is calculated:
    • Soffit Level = DS Invert Level + DS Height
  2. The lowest Soffit Level of all incoming pipes is determined from Step 1.
  3. For pipes connected to the node with a missing invert level and known Height, the invert level is calculated as:
    • Incoming Pipes:

      • DS Invert Level = Lowest Soffit of incoming pipes - Pipe DS Height

    • Outgoing Pipes:

      • US Invert Level = Lowest Soffit of incoming pipes - Pipe US Height

Invert from Gradients

Pipe US Invert Level and DS Invert Level values, for a pipe with one missing invert level, are inferred from the pipe's known invert level and the shallowest gradient of connecting pipes.

For a pipe with either the US Invert Levelor the DS Invert Level missing, and a valid Height and Length(i.e. greater than zero):

  1. A search is made for pipes connected to the other side of the node at which the pipe invert level is missing.
  2. The gradients for connected pipes found in Step 1 are calculated from:

    For gradients to be calculated, pipes must have:

    • Known US Invert Leveland DS Invert Level
    • Length > 0
    • Length < Maximum Pipe Length (specified in Inference Editor)
  3. The shallowest gradient calculated in Step 2 is determined:

    For a gradient to be used in inference the following criteria must be satisfied:

    • Gradient > 0
    • Gradient < Maximum Pipe Gradient (specified in Inference Editor)
  4. The difference between US and DS invert levels of the pipe with the missing invert level is calculated as:

    5. ΔH = Shallowest gradient determined in Step 3 x Pipe Length

  5. Missing invert levels are calculated as:
    • US Invert Level = DS Invert Level + ΔH (Step 4)
    • DS Invert Level = US Invert Level - ΔH (Step 4)
  6. The soffit level of the pipe at the inferred invert is calculated:
    • Inferred invert + US/DS Height

    If the calculated soffit level is greater than the Ground Level at the pipe's connecting node, inference will not be carried out.

  7. If no gradient has been found then attempt to find a gradient at the conduit's non-missing invert level end by repeating steps 2 to 6.

Invert from Lateral Connection

The invert level at a lateral connection is inferred from invert levels of the pipe to which it is attached, and the ratio of the distances of the lateral connection from the upstream and downstream nodes of the main pipe.

Inference will not be carried out if:

  • Main Pipe Length<= 0
  • Lateral distance from upstream node > Main Pipe Length
  • Lateral distance from upstream node < 0

Click on the image below to reveal the Invert from Lateral Connection example.

Example

Invert from Lateral Connection Example

  • A lateral pipe is missing an invert level at point C
  • The main pipe to which it is attached AB, has known invert levels
  • x is the distance of lateral node C from the US node Aof the main pipe.
  • L is the Pipe Length of pipe AB

The ratio, R, of the lateral distance along the length of the pipe is calculated as:

R =x / L

The invert level at node C is calculated as:

(R x DS Invert Level of AB) + [(1-R) x US Invert of AB)]

Invert Interpolate from Inverts

The invert level at a pipe is inferred from the invert levels of connected upstream and downstream pipes:

  • If there are connected pipes with known invert levels at the location of the invert to be inferred, the unknown invert level is inferred directly from a connected pipe invert.
  • If the invert levels of connected pipes at the location of the invert to be inferred are unknown, the unknown invert level is inferred by linear interpolation between known upstream and downstream inverts.

Direct Inference from Connected Pipe Invert

If there is a single connected pipe with known invert level at the location of the invert to be inferred, the invert level at the connected end of the pipe will be used.

If there are multiple connected pipes with known invert levels at the location of the invert to be inferred; the invert level at the connected end of the shortest pipe is used.

Click on the image below to reveal the related example.

Example

Inference by Linear Interpolation

The invert level of a pipe is inferred by linear interpolation between known upstream and downstream inverts:

  • Step 1: For each pipe with missing invert levels, the system searches upstream and downstream for the closest known upstream and downstream invert levels (including invert levels of the pipe for which values are being inferred).
    • If there are multiple known invert levels at the same distance, the lowest value is taken.
    • If there is a current selection of pipes, invert levels of selected pipes will be used in preference to invert levels of non-selected pipes.
  • Step 2: Missing invert levels are calculated using linear interpolation between the known upstream and downstream invert levels found in Step 1.

Click on the image below to reveal the related example.

Example

  • A run of pipes A-D has unknown invert levels at B and C.
  • Pipe AB is selected for inference
  • The Interpolate from Inverts rule searches upstream and downstream to find the known inverts:
    • US Invert Level of pipe AB
    • DS Invert level of pipe CD
  • The DS Invert Level of pipe AB is calculated as:

D + [x *(D-A)]/L

where:

D = DS Invert Level of pipe CD

A = US Invert Level of pipe AB

x = Distance from downstream node of Pipe AB to node D

L = Total Length from node A to node D
Parent topic: Inference Data Editor

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