Key Arc 8 additions to the network dialogue Review L&T Chapter 5 pages , Zeiler Chapter 8 Aspects of ESRI network –geometric network the “actual” mapped thing consisting of features with geographic aspects etc –logical network graph (L&T 176) showing relationships of connectivity –components –edge and junction

Edges (basics) geometric manifestation –typically single geometric element (polyline) connecting two nodes –members of feature class logical manifestation –pointers to geometric features possibly from many different feature classes ID Geometry Attributes Element ID Feature class ID Feature ID ID Geometry Attributes Feature class 1 Feature class 2

Junctions (basics) geometric manifestation –point features same geographic locations as nodes that are ends of some (not all) linear features linear feature “end” nodes are NOT automatically junction features logical manifestation –intersections, ends of edges –table of pointers to point features ID Geometry Attributes Point feature class 1 Point feature class 2 Element ID Feature class ID Feature ID

Features to logical elements Water Main feature line class Service Line feature line class ID Geometry Attributes Service Tap (point) feature class Meter feature (point) class ID Fea class ID Fea ID Junction Features Edge Element Junction Adj Jun Adj Edges Connectivity

Junctions and edges There need not be any one-to- one relationship with a node in the geometric network and a junction in the logical one Appropriate nodes in a geometric network will need to be designated as junctions Nodes junctions

Simple vs complex edges A simple edge has a one to one correlation between the network feature and the logical network element Main 2 S 1 S2 Me 1 Me 2 T 2 T 1 Water Main feature line class Service Line feature line class ID Geometry Attributes Service Tap (point) feature class Meter feature (point) class

Splitting simple edges To manage as simple features will need to break signal main into three features Water Main feature line class ID Geometry Attributes ID Fea class ID Fea ID Ma 1 Ma 2 Ma 3 S 1 S2 Me 1 Me 2 T 2 T 1 Ma 1 Ma 2 Ma 3 ID Geometry Attributes S 1 S 2 Service Tap feature class Edge elements

Splitting complex edges To manage a complex edge the single feature can have junctions placed along edge w/out actually breaking feature Water Main feature line class ID Geometry Attributes ID Fea class Fea Sub ID ID ID 1 Main Main Main Ser Ser 2 1 Main 1 S 1 S2 Me 1 Me 2 T 2 T 1 Main 1 ID Geometry Attributes S 1 S 2 Service Tap feature class Edge elements

Complex junctions Complex junctions reflect situations such as an electrical switch where the “inside” of the geometric feature actually has capabilities to “redirect” flows through network Geometry stays constant but network logical structure changes States of switch can be reflected in different logical network structures Geometric

Network flows Flows are reflected in a flow column in the logical network Flows are defined as “with” or “against” the digitized direction of the element ID Fea class Fea Sub Flow ID ID ID 1 Main 1 1 Against 2 Main 1 2 With 3 Main 1 3 With 4 Main 2 1 Against 5 Main 2 2 With Edge elements w/ flows Overall direction of flow Arrows reflect direction element was digitzed M1 M2 M3 M4 M5

Source and sink An individual node geometry may actually serve the role of a source or a sink in the logical network –sources spring in river water tank water well electrical generating station house sewer outflow –sinks water meter on house electrical meter waste water treatment plant A column “Ancillary Role” is added to junction table in logical network –entries in column ‘source,” “sink” or blank

Weights In the current release of Arc 8 weights can be applied to both edge and junction features weights can be viewed as the cost (time etc.) to traverse an edge or junction. some limitations –apparently Arc 8 DOES NOT support turn tables –nor does it support allocation applications