ArcGIS Pro

Utility Network Error Management: Water Topology Errors

Introduction

The first time you run the validate topology tool on your utility network and encounter a topology error you will likely ask yourself three questions:

  1. What caused this error?
  2. How can I fix this error?
  3. What can I do to prevent this from happening again?

The purpose of this article is to provide water industry specific examples for the most common errors so you are better equipped to answer these three questions. The different resolutions aren’t always immediately obvious, and we hope this guide will help you quickly identify the solution that’s the best choice for your data and your specific situation. If you haven’t already seen the first article in this series Utility Network Error Management: Topology Errors, I recommend you read that article first since it provides good context for these errors and provides a convenient chart you can use to reference for the different error types.

You can use the following links to quickly navigate to the the different errors:

Error Type Error Description
Junction-Edge Errors 8: Invalid connectivity – No junction edge rule
Ambiguous Connectivity 9: Invalid connectivity – More than one junction edge rule applicable
Edge-Edge Errors 10: Invalid connectivity – The edges are different subtypes and cannot connect
Stacked Points 25: Stacked point features
Invalid Terminal Connections 36: The line feature has an invalid terminal
Midspan Terminal Devices 38: Devices with multiple terminals cannot be midspan

Junction-Edge Errors

Fix Incorrect data

If you incorrectly classify service valves as system valves you will get an error.

Water Junction Edge Error #1
Water Junction Edge Error #1

This is because the rules of the water model do not allow system valves to connect to service lines.

Water Junction Edge Error #1a
Valve with no corresponding rules

To fix the error you set the asset group and asset type of the service valve to the correct type of service valve for the service line (hydrant, service, etc.).

Water Junction Edge Fix #1
Water Junction Edge Fix #1

Add a rule

You must add rules to your network any time you add a new asset type, like a new type of fitting, to your model.

Water Junction Edge Error #2
New fitting without any rules

If you place one of these features that doesn’t have any rules that allow for connectivity you will receive errors on it and will be unable to update the corresponding subnetwork.

Water Junction Edge Error #2a
Water Junction Edge Error #2

To fix the error an administrator would need to add the rule(s) required for the new type of feature to allow it to connect to different lines, junctions, devices.

Water Junction Edge Fix #2
Add a rule for the new asset

They will also need to add the new asset type to the subnetwork definitions for the system and pressure tiers.

Water Junction Edge Fix #1a
Add the new asset to the subnetwork definition

Once the rules and subnetwork definition have been updated you can then validate the area to ensure the error is resolved.

Water Junction Edge Fix #2a
Water Junction Edge Fix #2

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Ambiguous Connectivity

Use Terminal Connections tool

For example, if you forgot to assign the terminal connections on the lines after creating a pump you will run into this error.

Water Ambiguous Connectivity Error #1
Water Ambiguous Connectivity Error #1

To correct the error, you can use the assign terminals tool on each line that connects to the pump to assign the line to the inlet / outlet of the pump. For other types of features, the naming convention of the terminals may be different but the process for assigning terminal connections is the same.

Water Ambiguous Connectivity Fix #1
Use the modify terminal connections tool

Once you’ve made and validated the edits, the errors will disappear.

Water Ambiguous Connectivity Fix #1a
Water Ambiguous Connectivity Fix #1

Remove the invalid rule

By default, the water model allows transmission main and distribution main to be on both the high-pressure outlet and low-pressure inlet of a pump. This means you must use the terminal connection tool when connecting a main to a pump station to assign it to the right terminal.

Water Ambiguous Connectivity Error #2
Water Ambiguous Connectivity Error #2

If your data only allows for transmission to be on the high-pressure outlet and distribution on the low-pressure inlet, then you can adjust your rules to only allow transmission on the high-pressure side and distribution on the low-pressure side.

Water Ambiguous Connectivity Fix #2a
Remove invalid transmission main terminal rule
Water Ambiguous Connectivity Fix #2b
Remove invalid distribution main terminal rule

This will ensure that transmission mains are always connected to the high-pressure outlet. This also automatically connects mains to the correct side of the pump, meaning you don’t have to use the terminal connection tool to resolve the error.

Water Ambiguous Connectivity Fix #2c
Water Ambiguous Connectivity Fix #2

Move one of the features

If you have a service valve drawn on top of a service tee, tap, or other fitting you will want to offset the service blow off valve by moving it away from the saddle, along the service line. This will often result in many different errors appearing at the same time:

  1. Ambiguous connectivity error because the junctions and lines each have multiple rules
  2. Stacked point feature errors for the junction and device.
  3. Edge-Edge errors for the underlying lines because none of the junctions or devices at the area have connected the edges
Water Ambiguous Connectivity Error #3
Water Ambiguous Connectivity Error #3

To fix the error, you offset the junction and device.

Water Ambiguous Connectivity Fix #3
Water Ambiguous Connectivity Fix #3

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Edge-Edge Errors

Edit the line features to match

When importing service information from external systems, you may end up with inconsistent asset types in your data. When you connect inconsistent services you will get an edge-edge error.

Water Edge Edge Error #1
Water Edge Edge Error #1

If you look at the two connected services and find that they are the same asset type you can correct the error by updating the asset type on improperly classified pipe or by merging the two lines into a single line.

Water Edge Edge Fix #1
Water Edge Edge Fix #1

Create a point feature between the two lines

The most common example of a missing junction is when a service is connected directly to a main without any kind of fitting.

Water Edge Edge Error #2
Water Edge Edge Error #2

To fix the issue, you would place a fitting at the location where the two pipes are connected. You should make a note or indicator to keep track of these junctions for follow-up. Their location and materials are approximate and will need to be confirmed by referring to source drawings, work orders, or field verification.

Water Edge Edge Fix #2
Water Edge Edge Fix #2

Move a line

The Utility Network prevents you from snapping different pipes together in a way that causes this error. This error most often occurs when a user accidentally splits overlapping lines or changes the classification of existing lines.

Water Edge Edge Error #3
Water Edge Edge Error #3

To fix the issue you would perform the following:

  1. Select the pipe that needs to be unsnapped
  2. Activate the edit vertices tool
  3. Move the vertex of the first line away from the second

This will cause the error to go away, but if this results in the feature becoming isolated from your network you will need to research how it is connected.

Water Edge Edge Fix #3
Water Edge Edge Fix #3

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Stacked Points

Delete one of the stacked features

When you import customer meter locations into the GIS for the first time, it is common for meters to be stacked on top of each other. Each stacked meter will result in a stacked point error.

Water Stacked Point Error #1
Water Stacked Point Error #1

If you can find that one of the stacked meters is a duplicate, then you should remove the duplicate meter.

Water Stacked Point Fix #1
Water Stacked Point Fix #1

Move one of the features

Let’s consider another situation during data cleanup data after importing customer meter locations. In this situation, we are cleaning up data at an address that has multiple meters.

Water Stacked Point Error #2
Water Stacked Point Error #2

In this situation you would unstack the meters and connect each one to its own service line. If your data does not have enough service lines, or if it is unclear which meter is associated with each service line, then you may need to perform a field check to find the true location of each meter.

Water Stacked Point Fix #2
Water Stacked Point Fix #2

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Invalid Terminal Connections

Reset terminal connection

If you delete, move, or reclassify a device with terminals, the line it was connected to will still have attributes that reference the terminal from the previous device. This often occurs when working with equipment near stations, supplies or isolation valves.

Water Invalid Terminal Error #1
Water Invalid Terminal Error #1

To fix this error, you edit the line feature with the error and set the corresponding terminal field, fromterminal or toterminal, to the value “None”.

Water Invalid Terminal Fix #1
Water Invalid Terminal Fix #1

Connect new terminal

If you replace a device with terminals with a device that has a different terminal configuration you will also receive these errors. In this example we originally placed an air gap flow valve on the line, assigned terminal connections, then later realized it was a check valve. After correcting the valve type, we now receive an invalid terminal error because check valves use a different terminal configuration.

Water Invalid Terminal Error #2
Water Invalid Terminal Error #2

Before you can use the modify terminal connections tool to assign the correct terminal you must manually set the terminal field, fromterminal or toterminal, to the value of “None”.  Once you’ve reset the terminal connection you can then use the modify terminal connections tool to assign the new terminal.

Water Invalid Terminal Fix #2
Water Invalid Terminal Fix #2

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Midspan Terminal Device

Split the Line

If you place a device with terminals on a line without splitting it first, you will receive this error. You are likely to receive this error when placing new check valves or system isolation valves.

 

Water Midspan Terminal Device Error #1
Water Midspan Terminal Device Error #1

To fix the issue you use the edit tool to split the line at the location where the device connects to the line. After you’ve split the line you will still need to use the modify terminal connections tool to connect the lines to the correct terminals on the device.

Water Midspan Terminal Device Fix #1
Water Midspan Terminal Device Fix #1

Move the device

Devices with terminals can only connect to the end of a line.  In this example you can see that we’ve placed the water treatment at the intersection of two transmission mains.

Water Midspan Terminal Device Error #2
Water Midspan Terminal Device Error #2

Before you split these mains we confirm whether the device is in the correct location and determine it should be moved first.  Once we’ve moved the supply is in the correct location we split the line and assign terminals. We then use the modify terminal connections tool to connect the lines to the correct terminals on the device.

Water Midspan Terminal Device Fix #2
Water Midspan Terminal Device Fix #2

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About the authors

Robert Krisher is a Product Engineer with Esri who has over 15 years of experience implementing Enterprise GIS for Utilities.

Remi is the Product Manager for the ArcGIS Utility Network and spends his free time exploring the US Southwest desert and California beaches.

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