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Junction-Edge connectivity

OliviaGill3

I've been doing some reading on different types of Geometric connectivity in the UN and am trying to find some clarification re: Junction-Edge connectivity. I believe this can only be applied to a line and a junction as a geometric connection, and only with a junction that has a terminal where the junction must be at the end of the line, rather than placed midspan. Is this correct?

The documentation is not completely explicit (which may be my misreading) but it explains that:

'Establishing a connection midspan along a line or edge object to a point or junction object with terminals requires a nonterminal point feature or junction object to be placed midspan, respectively.'

Doesnt this mean, by having a non-terminal point midspan that is connecting geometrically to a line, the rule statement is essentially contradictory? Any help or clarification is very much appreciated.

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RobertKrisher

@OliviaGill3 Terminal devices cannot be drawn midspan on lines, they must split them. Once the line is split the junction-edge connectivity rules apply, but if you don't split the line you get a topology error.

In most cases after splitting the line you will want to connect each line to a different terminal on the device, although in the case of drawing something like a fuse for a tap-line midspan (where it connects to three lines) you would connect the two lines on the upstream edge to one terminal, and the tap line to the other terminal. This configuration allows the fuse to be opened and only interrupt flow to the tap line, leaving flow on the mainline uninterrupted.

All comments

OliviaGill3

Thanks again. I understand how the midspan / terminals for junction edge works now. But in terms of points without terminals for junction-edge:

We have carried out a test on the UN model with some test data. We added a test junction without terminals midspan on a line. The junction has asset group and asset type attribute values of Unknown (and therefore do not exist in the rules configuration). We validated and saw that it doesn't raise an error for junction-edge, only an error where the junction has a non valid subtype. I guess given the premise that:

'Junction edge rules apply to any location where a point (device, junction, or junction object) is connected with a line (line or edge object). ' we would expect a junction-edge error here as well? Any info much appreciated.

RobertKrisher

OliviaGill3

Hi Joaquin - thanks for the very detailed response and example. I'll have a read! There is so much to learn!

OliviaGill3

Just as an additional comment on the limitations of midspan connectivity with termnials - would this not be managed by implementing an Edge Connectivity rule allowing for AnyVertex. Or in these examples do we need both a Junciton-Edge and also an EdgeConnectivity rule ? Thanks again for your time.

OliviaGill3

Hi Robert - that's clear, thank you. The link to the quote I used is on this page:

Network rules—ArcGIS Pro | Documentation

JoaquinMadrid1

As a follow up to Robert's explanation, let me elaborate using an Electric Utility use case nicely resolved by the UN: tapping a phase from a three-phase trunk down to a single-phase lateral.

In this (informal) example, consider the following:

A section of the three-phase trunk is made up of consecutive line segments connected to each other by their consecutive end vertices
You may want to tap
- Either any where within a single segment of the trunk (midspan tapping)
- Or where two segments connect (line end tapping)
- Or where a "last" segment finishes off the three-phase trunk (also line end tapping)
- The lateral stems off the trunk at this tapping point

Then you need to configure your UN as follows:

Two asset types for Line: say 3-phase and 1-phase (the names are not relevant)
- The 3-phase asse type must have Edge Connectivity Policy of 'Any Vertex' so that you can snap
  - Either at any End Vertex
  - Ot anywhere Midspan, allowing a new vertex to be created if at the snapping point there was not already one
  - NOTE: this workflow relies on ArcGIS Pro's Snapping Engine
One asset type for Junction: say Midspan Tapper
- You assign the OOTB Category 'Subnetwork Tap' to this asset type
One asset type for Device: say Line End Tapper
- You assign a terminal configuration to this asset type with two terminals, say
  - Connect to 3
  - Connect to 1
- NOTE: The need of terminals forces the Line End Tapper to be a Device
Two J-E Connectivity Rules
- Midspan Tapper to 3-phase
- Midspan Tapper to 1-phase
Two J-E Connectivity Rules
- Line End Tapper to 3-phase via Connect to 3
- Line End Tapper to 1-phase via Connect to 1
Configure your UN for Phase Propagation, driven by a phase network attribute, say E:Phase Driver
- Assigned to a phase field in the Device, Junction and Line feature classes

NOTE: I am illustrating this example without Non-Spatial Objects. But they could also be used accordingly.

With all this machinery at your disposal,

If you want to tap midspan, bring a Midspan Tapper to the map
- It will snap to the 3-phase
- You set the phase driving value, say 'B'
- You bring a 1-phase to the map, which will snap at the tapper
If you want to tap at a n end vertex, bring a Line End Tapper to the map
- It will also snap at the end vertex of the 3-phase
- You also set its phase driver to 'B'
- And you can also pull the lateral starting from it snapping to the tapper

In either case, if the Propagator were bringing 'ABC' phase from upstream, then

Propagation of 'ABC' downstream the trunk will not be interrupted by the tapper
The tapper will provide 'B' phase to the lateral

RobertKrisher

Can you post the link to the page in you pulled that quote from so I can pass it along to our doc team?

Junction edge rules apply to any location where a point (device, junction, or junction object) is connected with a line (line or edge object). If the point has terminals, then the rule will also include which terminal on the point the rule applies to. Junction-edge rules most commonly apply to geometric connectivity but can apply to non-spatial connectivity when they involve a non-spatial object (junction object or edge object).

The paragraph you're referring to discusses the limitations of midspan connectivity with terminals which requires either splitting the line or using a non-terminal device to represent the insertion point.

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