Fix topology errors in a utility network

The foundation of tracing and analysis using network data is a graph structure that defines how all the elements in the graph are connected. Creating a logical graph from spatial features requires maintaining a topology between these features to ensure that they are edited in a way that can be represented by the graph. The utility network is built on top of a network topology, and as such it imposes some restrictions on your data to ensure it can maintain a valid topology.

In this tutorial you will act as a GIS technician who is tasked with cleaning up all the topology errors in your utility network. You will be working on a data set that migrated to the utility network from a system that didn't maintain a valid topology. Each module of this tutorial is dedicated to a different constraint of the utility network and will show you how to identify and resolve the issue. The good news is that when data is edited in the utility network it will prevent most of these errors from being created and if a user does introduce one of these errors that can be quickly caught and resolved by validating the network topology.

You are encouraged to complete the tutorial Fix connectivity errors in a utility network before this one, but it is not required. If you are not already familiar with ArcGIS Utility Network, you are encouraged to first complete the tutorial Try ArcGIS Utility Network.

This tutorial was last tested on June 2, 2023, using ArcGIS Pro 3.1. If you're using a different version of ArcGIS Pro, you may encounter different functionality and results.

Requirements

• ArcGIS Pro Standard or Advanced (see options for software access)
• User, Publisher, or Administrator role in an ArcGIS organization: ArcGIS Online (see options for software access) or ArcGIS Enterprise (learn more)

Edit edge errors in a utility network

Fix an edge-edge error

The utility network uses feature restrictions and rules to maintain data accuracy and correctness. While network rules are defined by an administrator, and can be changed, feature restrictions are built into the utility network and can’t be modified or removed.

According to one feature restriction, when you connect two or more edges with different asset types, you must model a junction or device at that location. If you don’t, you will cause error 10: Invalid connectivity - The edges are different subtypes and cannot connect, also known as an edge-edge error. This feature restriction promotes data integrity by ensuring that the device or junction connecting two linear assets is recorded. These locations can become points of failure in a system, so having an accurate record of these connections allows you to better manage risk and maintenance.

Next, you’ll view an example of an edge-edge error (error 10). You’ll create a junction feature to connect two lines and resolve the error.

1. Download the Topology Errors project package.

   A file named Topology Errors.ppkx is downloaded to your computer.

   Note:

   A .ppkx file is an ArcGIS Pro project package and may contain maps, data, and other files that you can open in ArcGIS Pro. Learn more about managing .ppkx files in this guide.

2. Locate the downloaded file on your computer. Double-click Topology Errors.ppkx to open it in ArcGIS Pro.
3. If prompted, sign in with your ArcGIS account.

   Note:

   If you don't have access to ArcGIS Pro or an ArcGIS account, see options for software access.

   A map appears, of a water distribution utility network in Naperville, Illinois, USA.

   

4. On the ribbon, click the Map tab. In the Navigate group, click Bookmarks.
5. In the bookmark gallery, click Bookmark 1 to zoom to this bookmark.

   

   The map zooms to a residential service connection with two instances of error 10: Invalid connectivity - The edges are different subtypes and cannot connect.

   

   The red hatched rectangles are dirty areas, which serve as an indicator that a change to the network has taken place that is not reflected in the network topology.

6. In the Contents pane, expand the Water Network Utility Network layer and its Dirty Areas sublayer to see how dirty areas are symbolized on the map.

   

   The dirty areas at this bookmarked location are Error areas.

7. In the Contents pane, check the box next to Labels to turn this layer on.

   

   Labels appear on the map. These are not the typical labels found in a utility network map, but are intended to make feature identification easier throughout this tutorial.

   

   The errors surround two lines: a Service, Residential Service line and a Water Main, Distribution Main line. The error labels explain that the edges (lines) are different subtypes and therefore cannot connect.

   Utilities will often have services that connect directly to their mains because the services were installed before there were processes in place to record the material and location of the service and tap. To resolve the error, you need to place a junction or device at the location where the service line touches the water main line. You don’t have any information about how they are connected, so you will follow the drawing standards and rules for your utility network: you’ll place a tap pipe fitting at the intersection of the main and service lines.

8. On the ribbon, click the Edit tab. In the Snapping group, ensure that the Snapping button is highlighted in blue to indicate that snapping is turned on.
9. Click the lower half of the Snapping button. Ensure that the first four snapping options are turned on.

   

10. In the Features group, click Create.

    

    The Create Features pane appears.

11. In the Create Features pane, in the search bar, type tap. In the search results, under Water Junction : Fitting, click the Tap template.

    

    On the map, the cursor is replaced with a Tap fitting symbol.

12. Point to the intersection of the two lines. When the snapping ToolTip says Service : Endpoint, click to create a feature at that location.

    

    Note:

    When editing your own utility network, you should investigate the features installed in the field and record attributes (such as diameter and installation date) as you create features.

    Next, you’ll validate your edits.

13. On the map, zoom out until you can see both dirty areas fully.

    

    By default, the Validate command only validates dirty areas within the current map extent.

14. On the ribbon, click the Utility Network tab. In the Network Topology group, click Validate.

    

    All of the dirty areas and error labels disappear. This part of the map is now validated and error free.

    

    Next, you’ll clear the selection and save your edits.

15. On the ribbon, click the Edit tab. In the Selection group, click Clear.

    

16. In the Manage Edits group, click Save.
17. In the Save Edits window, click Yes.

    In this section, you resolved an edge-edge error (error 10) by creating a valid junction to connect the two edge features. Another way to resolve this error that might be appropriate in other situations is to change the Asset type of one of the lines.

    If your data does not consistently model the fittings in the field, especially on services, you may run into many edge-edge errors. You should adjust your editing workflows to begin accounting for these features.

Resolve stacked point feature errors

Fix a stacked points error

It is common for features in a map to be co-located. The utility network allows co-locating a device or junction on a structure, but if you attempt to place a device or junction on top of another device or junction, it will cause error 25: Stacked point features. When there are multiple devices or junctions at a location, the connectivity between them cannot be determined.

In this section, you’ll view an example of a stacked point error (error 25). To resolve it, you’ll move one of the point features to an offset location.

1. On the ribbon, click the Map tab. In the Navigate group, click Bookmarks.
2. In the bookmark gallery, click Bookmark 2 to zoom to this bookmark.

   The map zooms to an area with multiple errors.

   

3. On the map, zoom in to the intersection of the dirty areas.

   As you zoom in, you can see that there are three dirty areas, surrounding the following features: a Service, Residential Service line, a Water Main, Transmission Line, and two coincident point features: Service Valve, Service and Fitting, Tap.

   

   There are many errors in this area. It is best to resolve non-connectivity errors first, since they may be causing the connectivity errors. In this case, the non-connectivity error is error 25: Stacked point features, which occurs because the service valve is stacked on top of the tap. This error is the cause of the other errors:

   • Error 9: Invalid connectivity – More than one junction edge rule applies, also known as an ambiguous connectivity error, occurs because the utility network is unable to determine whether to connect the pipes to the valve or the tap.
   • Error 10: Invalid connectivity – The edges are different subtypes and cannot connect, also known as an edge-edge error, occurs because the service and main are attempting to connect to each other, but they were unable to determine whether to use the valve or the tap as their connecting junction.

     If you correct error 25, it will also resolve errors 9 and 10. Before you begin editing, you’ll turn the dirty areas off so you can more clearly see the features being edited.

4. In the Contents pane, turn off the Water Utility Network layer.

   The error polygons and labels disappear from the map.

   

   From your familiarity with water systems, you know that services are always connected to water mains with taps, and service valves are usually placed on the service, offset from the tab by a few feet. To correct the errors in this area, you’ll move the service valve away from the tap.

5. On the ribbon, click the Edit tab. In the Tools group, click Move.

   

   The Modify Features pane appears.

6. On the map, click the Service Valve, Service feature to select it.
7. In the Modify Features pane, confirm that the selected feature is Water Device : Service Valve (1).

   

   Because there are two points in this location, it’s important to confirm that you have selected the correct one.

8. On the editing toolbar, click the Disconnect button so it is highlighted in blue.

   

   This will allow you to move the service valve while leaving all the other features in place.

9. On the map, drag the selected feature a short distance away from the intersection along the service line. Ensure that the snapping ToolTip says Service : Edge.

   

10. On the editing toolbar, click the Finish button.

    

11. In the Contents pane, turn the Water Utility Network layer back on.

    

    Two of the dirty areas have changed from the red Error symbol to the blue and red Dirty and Error symbol. A new Dirty and Error area was also created around the moved service valve. The Dirty and Error symbol indicates that a feature that had an error has been edited and now needs to be validated again.

12. On the map, zoom out until all four dirty areas are fully visible.
13. On the ribbon, click the Utility Network tab. In the Network Topology group, click Validate to validate your edits.

    All of the dirty areas disappear from the map.

    

14. On the ribbon, click the Edit tab. In the Selection group, click Clear.
15. In the Manage Edits group, click Save. In the Save Edits window, click Yes.

    In this section, you resolved a stacked point error (error 25) by offsetting one of the points. This change also resolved the connectivity errors caused by the stacked point. Another way to resolve this error that might be appropriate in other situations is to delete one of the points.

Avoid a stacked point error

In addition to resolving errors, it’s important to know how to avoid them. Next, you’ll view a common scenario that can lead to error 25: Stacked point features. In this example, two meters are located at the end of a service line, but they both can’t be modeled there without causing an error. You’ll model them offset from the line with a connectivity association.

1. Zoom to the Bookmark 3 bookmark.

   The map zooms to a location with a residential service line leading to a house.

   

   You need to represent two meters at this location, but if you place both meters at the end of the line, it will result in a stacked point error (error 25). In this tutorial, you will avoid the error by drawing both of the meters offset from the line.

2. Reopen the Create Features pane.

   Tip:

   If you can’t find the Create Features pane, on the ribbon, click the Edit tab. In the Features group, click Create.

3. In the Create Features pane, search for residential. Under Water Device : Service Meter, click the Residential template.

   

4. On the map, click a short distance north of the end of the Service, Residential Service line.
5. Click again, this time a short distance south of the end of the line.

   Two Service Meter, Residential features are created.

   

   Next, you’ll create a service connection to connect the two meters to the service line.

6. In the Create Features pane, under Water Device : Service Connection, click the Residential template.

   

7. On the map, point to the end of the Service, Residential Service line. When the snapping ToolTip says Service : Endpoint, click to create a feature.

   

8. Leave the new Service Connection, Residential feature selected.

   Next, you’ll create connectivity associations between the service connection and the service meters.

9. On the ribbon, click the Utility Network tab. In the Associations group, click Modify.

   

10. In the Modify Associations pane, click Load selected.

    The associations for the selected Service Connection, Residential feature appear. Currently there are none.

    

11. Expand the Junction – Junction (0) section. Click the cursor button next to the Add selected button.

    

12. On the map, click each of the Service Meter, Residential features.

    The two features are added to the Modify Associations pane.

    

13. At the bottom of the pane, click Apply.

    Connectivity associations have been created between the service connection and the service meters.

14. On the ribbon, on the Utility Network tab, in the Associations group, click View.

    

    Dashed lines appear on the map, connecting the three new features, confirming their connectivity association.

    

    Tip:

    You can also view which features are connected to the Service Meter, Residential feature in its pop-up.

15. On the ribbon, click View to turn off the association lines.
16. Close the Modify Associations and Create Features panes.
17. On the map, zoom in to the new features.

    

    A blue dirty area surrounds each feature. These appeared when the features were created, so you may have noticed them earlier. The dirty areas indicate there are unsaved edits that need to be validated.

18. Ensure that all three dirty areas are within view and validate your edits.
19. Clear the selection and save your edits.

    

    You have successfully created valid connectivity associations between the service meters and the service connection and fixed the stacked point errors. Avoiding stacked point errors not only keeps your network error free, but it also makes it easier to see and understand how all features are connected to one another.

20. Save the project.

In this module, you learned how the utility network reports errors for stacked features along with how you can resolve and avoid these errors going forward. Avoiding stacked point errors not only keeps your network error free, but it also makes it easier to see and understand how features in your network are connected to one another.

Resolve midspan connectivity errors

Fix a midspan connectivity error

The connectivity configuration of a line controls whether other features can connect to any vertex on the line or are constrained to only connect to its endpoints. In some systems, these may be referred to as complex (any vertex) or simple (endpoints only) lines. An example of a complex line is a water main, which allows features such as saddles to be installed midspan without splitting the line. An example of a simple line is a service. Services must always be split to install equipment on them.

In this section, you’ll view an example of error 13: Midspan connectivity not allowed, also known as a midspan connectivity error. To resolve it, you’ll split the line in two.

1. Zoom to the Bookmark 4 bookmark.

   The map zooms to a hydrant service line with a hydrant service valve installed on it and two instances of error 13: Midspan connectivity not allowed.

   

   Hydrant service valves are allowed to connect to hydrant service lines, but hydrant service lines are configured to not allow features to connect midspan. This is because any fitting or valve installed on a service line must physically break the service line in the field. To correct the error, you will split the service line.

2. On the ribbon, click the Edit tab. In the Tools group, click Split.

   

   The Modify Features pane appears.

3. On the map, click the Service, Hydrant Service line to select it.
4. On the map, point to the Service Valve, Hydrant feature. When the snapping ToolTip says Service Valve : Point, click to split the line in half.

   

   The dirty area surrounding the service line changes to the Dirty and Error symbol.

   

5. Ensure that all dirty areas are within view and validate your edits.
6. Clear the selection and save your edits.

   The errors are resolved.

   

   In this section, you resolved a midspan connectivity error (error 13) by splitting a service line. Other ways to resolve this error that might be appropriate in other situations are to move the point, or delete the point or line. The utility network was configured to not allow this kind of connection for a reason. However, if you have a lot of these errors, you should consider the benefits and impacts of changing your model to allow for midspan connectivity. You can ask your administrator to change the edge connectivity policy for the feature.

   Note:

   To learn how to resolve this error by changing a configuration, see Allow midspan connectivity on a line in the tutorial Configure rules for a utility network.

Fix a midspan terminal device error

A device with terminals cannot be drawn midspan to a line, regardless of its midspan connectivity configuration. Terminal connection information is stored on the line. The From device terminal and To device terminal fields on the line define which terminal the line is connected to on either end; there is no method for defining a terminal connection midspan. Therefore, devices with terminals must be placed on either end of a line.

In this section, you’ll view an example of error 38: Devices with multiple terminals cannot be midspan, also known as a midspan terminal device error. To resolve it, you’ll split the line in two and modify the terminal connections of the device.

1. Zoom to the Bookmark 5 bookmark.

   The map zooms to an isolation system valve (labeled as System Valve, Isolation Zone) that has been drawn midspan on a Water Main, Distribution Main line. Isolation valves have terminals that allow them to identify isolation zones, and this valve is drawn midspan on a water main, causing the following error: 38: Devices with multiple terminals cannot be midspan.

   

2. On the ribbon, click the Edit tab. In the Tools group, ensure the Split tool is active (highlighted in blue).
3. In the Modify Features pane, ensure that either Select one or more lines or polygons or Change the selection is active (highlighted in blue).

   

4. On the map, click the Water Main, Distribution Main line to select it.
5. On the map, point to the System Valve, Isolation Zone feature. When the snapping ToolTip says System Valve : Point, click to split the line at this location.

   

   The dirty area changes to the Dirty and Error symbol. The water main line is now two lines. Next, you need to connect each line to the terminals on the isolation system valve. If you don’t, you’ll cause an ambiguous connectivity error (error 9) when you validate the edits.

6. Close the Modify Features pane and clear the selection.
7. On the ribbon, click the Utility Network tab. In the Network Topology group, click Terminal Connections.

   

8. In the Modify Terminal Connections pane, ensure that either Select a line feature or Change line selection is active (highlighted in blue).

   

9. On the map, click the water main line to the left (west) of the valve to select it.

   

10. In the Modify Terminal Connections pane, for From: System Valve, ensure that Terminal is set to Port One.

    

11. Click Apply.
12. On the map, click the water line to the right (east) of the valve to select it.
13. In the Modify Terminal Connections pane, for To: System Valve, change Terminal to Port Two.

    

14. Click Apply.

    It is important when assigning terminals to ensure that you are not connecting more than one line to a single terminal, especially when that device can be opened or closed. If both pipes connect to a valve through the same terminal, the valve will be bypassed during tracing: water will flow from one pipe to another without passing through the valve. Closing the valve will not stop the flow of water as it should.

15. On the map, zoom out until you can see the entire dirty areas.

    

16. Validate your edits.

    The dirty area disappears.

    

17. Clear the selection and save your edits.

    Note:

    To learn how to resolve this error by changing a configuration, see Fix midspan terminal device errors in the tutorial Configure rules for a utility network.

18. Close the Modify Terminal Connections pane.
19. Above the ribbon, on the Quick Access Toolbar, click the Save button to save the project.

    

    In this module you learned that the utility network allows you to control which types of lines or devices are required to split lines, and how you can configure this behavior to meet your needs. You also learned several techniques for correcting these errors in situations where your configuration is correct, but your data is wrong.

In this tutorial, you learned about errors that can arise when data is incorrectly drawn, and techniques to avoid or correct these errors. In particular, you learned about edge-edge (error 10), stacked points (error 25), midspan connectivity (error 13), and midspan terminal device (error 38) errors. You now know more about how utility network rules help to keep your data accurate and consistent.

Next, try the tutorial Configure rules for a utility network to learn how to resolve and prevent topology errors by changing rules and other utility network configurations. To learn more about utility network topology errors, try the following resources:

• For examples and solutions for all topology errors, read the articles in the Managing Topology with ArcGIS Utility Network series.
• If you have a dataset with a lot of errors, download the Utility Data Management Support Tools and run the SummarizeUNErrors tool to generate reports to help prioritize data cleanup.
• To experiment with a sample utility network, try one of the utility network foundation solutions.

You can find more tutorials in the tutorial gallery.

Acknowledgements

• Map data: used with permission from the City of Naperville
• Cover photo: GioRez - stock.adobe.com
• Light Gray Canvas map sources: Esri, HERE, Garmin, FAO, NOAA, USGS, OpenStreetMap contributors, and the GIS User Community