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Network attributes

Network attributes are associated with attributes on features in your network. They are derived from feature attributes and cached inside the network topology to aid in performance as feature attributes are evaluated during a trace or while performing subnetwork management tasks. The values stored on the attributes on your features in a map are reflected or updated in the associated network attribute each time you validate the network topology.

Existing network attributes in a utility network can be viewed in the Network properties dialog box for the utility network. The Attributes and Assignments section includes detailed properties of existing network attributes and their assignments (feature class and field the network attribute is assigned to). This includes the system-provided and user defined network attributes for a utility network.

There are two system-provided network attributes in a utility network:

  • Shape length—Associated with the Shape_Length field on the Line feature class. This is an apportionable network attribute that can be used to calculate the total length of a trace; for example, a group of pipes or a portion of a pipe.
  • Is subnetwork controller—Associated with the Is Subnetwork Controller field on the Device feature class. This is a system-maintained field that is altered when Device features are set as a subnetwork controller.

Create and assign network attributes

User defined network attributes are created using the Add Network Attribute tool, and assigned to a feature class attribute field using the Set Network Attribute tool.

When creating a new network attribute using the Add Network Attribute tool, the data type chosen for the Attribute Type parameter will determine what options are available to define the network attribute. This will also determine what attribute fields the network attribute can be assigned to after it is created using the Set Network Attribute tool as the data types must match.

Creating a network attribute using the In Line option requires an input attribute domain that is used to calculate the number of bits to store in the network topology. A maximum of 23 bits are reserved in the network topology for user defined network attributes that are created using the In Line option. When this bit size is exceeded an error will be returned when creating a new network attribute.

The Attribute Type used when creating a new network attribute determines what properties are available:

  • Short
    • In Line—Domain Name is required for attribute domain
    • Nullable—Supports null values
  • Long
    • In Line—Domain Name is required for attribute domain
    • Substitution—Available when In Line is false
    • Nullable—Supports null values
  • Double
    • Apportionable—Line class only
    • Nullable—Supports null values
  • Date
    • Nullable—Supports null values

In Line—Specifies whether the network attribute is persisted inline. The most frequently used network attributes should be stored with the In Line property set to True. This property can only be set when the Attribute Type is an integer data type of Short or Long. Network attributes defined as In Line that are nullable include an extra bit added to the overall bit size. If a network attribute is created as In line, the expectation is that the same geodatabase domain is assigned to the field that was used when creating the network attribute. Also, the values for the field must be positive. If the same network attribute is assigned to multiple classes and attributes, the expectation is that the network attribute has the same representation across classes. These network attributes are then available as a filter when configuring a trace.

Apportionable—Specifies whether the network attribute will be apportioned across multiple edges belonging to the same feature. The distribution of the value depends on the percentage along each edge element with respect to the from point of the original feature. This property can only be set to True when the Attribute Type is Double. Network attributes with the Apportionable property can only be assigned to fields on the structure and domain network line feature classes.

Substitution—Specifies whether the network attribute can be configured for attribute substitution. The Substitution property can only be set to True for network attributes with an Attribute Type of Long when the In Line property is False.

Some important notes about configuring network attributes:

  • To assign a network attribute to an attribute field using the Set Network Attribute tool, it must have a compatible data type as listed above. If an attribute field with the correct data type is not present to set the network attribute, one can be added using the Add Field tool.
  • Network attributes that are defined as not nullable can only be assigned to fields that are not nullable.
  • There is no limit to the number of network attributes a single utility network can have, but a network attribute can be associated with only one attribute per feature class. This means that once a network attribute is set on a network class for a specified field, no other network attribute assignments can be set on that field.

Advanced network attribute configuration

It is appropriate to use network attributes when modeling a characteristic of assets with more than one state (for example, phase or pressure). Network attributes are used during attribute propagation and attribute substitution. Propagation uses network attributes to propagate calculated values during a trace or subnetwork management event. Substitutions allow you to swap propagated values out for other values; for example, AC becomes BC. To work with attribute substitution, the network attribute must be created with the Substitution property set to True and a Network Attribute to Substitute defined.

To learn more about these configurations, see Attribute propagation and Attribute substitution.

Work with network attributes

When attribute edits are made to fields defined as network attributes, dirty areas are created. Validating the network topology ensures the latest is stored for the network attributes for analytic events.

When updating a subnetwork, network attributes can be used to define the features that will be updated. This is controlled by the subnetwork definition set for a tier. Filters are used to apply the update to only features with a certain attribute value—for example, only AB phase, where phase is the network attribute and AB is the filter value.

Network attributes are also used as weights to control traversability and to model the cost of tracing paths in the network. For example, in a water network a certain amount of pressure is lost when traveling the length of a transmission main due to surface friction in the pipes. The network attribute value in this example is derived from the length attribute of the transmission mains.

Apportionable network attributes

For apportionable network attributes, analytic results are more precise because apportionable values such as line length, impedance, or other flow characteristics will be computed for the more accurate locations of tap features on a line. This means that trace configurations using apportionable network attributes with a function (Add, Average, Count, Max, Min, and Subtract) will return apportionable results based on edge elements of the network features.

The image below provides two examples:

  • The top image shows a connected line feature with a single edge. The graphic has one line feature and two junction features. Two line end junction features are spatially coincident with the end-vertices of the line. This is the simple case of a connected line feature in a utility network.
  • The bottom image shows a connected line with two edges. The graphic has one line feature and three junction features. A tap junction feature is added and snapped to a vertex. This logically divides the line feature into subparts that are called edges. An edge is a set of one or more line segments between two junction features that are connected to a line feature. When doing analysis on apportionable network attributes, edges are collected to more precisely define the scope of analysis.
Edges and lines in a utility network
To reflect real utility systems, the utility network lets you place many junction features on the vertices of a long line feature. This is useful when you want to model many service points over a single line feature that extends some distance. Secondary lines are then connected to the junction features.

To learn more about tracing with network attributes, see Configure a trace.

Also, see Subnetwork trace configuration to learn how network attributes are used within the subnetwork definition of a tier.