URBDP 422 Urban and Regional Geo-Spatial Analysis Network Analysis Team Work Time VIII February 25, 2014

What is Network Analyst Types of Analysis Types of Networks Network Analyst Tools Network Components Designing and Creating a Network Dataset Example Tips and Tricks Overview

estimate the draw a park may have with local residents – that commute via car verses bike Example:

System of interconnected elements, such as edges (lines) and connecting junctions (points), that represent possible routes from one location to another. What is a network?

The ArcGIS Network Analyst extension allows you to build a network dataset and perform analysis on a network dataset Used primarily on Transportation Networks What is Network Analyst?

Facilities and incidents: the start and end points of routes –Fire stations and house fires Barriers: represent those parts of the network that are specified as impassable –Underpasses or tunnels that are too short or narrow for large fire engines Routes: the least cost path between two points in the network Terms

Answers 8 main problems, questions, or tasks: Drive-Time Analysis Point-to-Point Routing Route Directions Service Area Definition Shortest Path Optimum Route Closest Facility Origin-Destination (OD) Cost Matrix Types of Analysis

Brainstorm: Think of 2-3 questions related to planning that would be best addressed with a network analysis software? How might network calculations help you answer questions related to your class research project? Class questions

Network Example: Optimal Routing Delivery schedule and route Best route to single or multiple destinations Bus routes Multi-tasked day Running errands

Optimal Route: Shortest Route

Sewer Pipes Exploded on streets and Have formed a barrier for delivery!

The food still gets there!!!!

Transportation Network –Undirected networks. –Free to decide the direction, speed, and destination of traversal. –For example, a person in a car traveling on a street can choose which street to turn onto, when to stop, and which direction to drive. –Restrictions imposed on a network are guidelines –Modeled using network datasets. Types of Networks

Utility Network –A utility network is directed. –Flows along the network based upon certain rules built into the network. –The path is predetermined –The engineer controlling the network can change the rules of the network by opening some valves and closing others to change the direction of the network. –In ArcGIS, utility networks are modeled using geometric networks. Types of Networks

Networks used by ArcGIS Network Analyst are stored as network datasets A network dataset is created from the feature source or sources that participate in the network It incorporates an advanced connectivity model that can represent complex scenarios, such as multimodal transportation networks It also possesses a rich network attribute model that helps model impedances, restrictions, and hierarchy for the network The network dataset is built from simple features (lines and points) and turns Network Datasets

This extension is composed of a number of parts: – wizard to create a network dataset (in ArcCatalog) – Network Analyst toolbar (in ArcMap) – dockable Network Analyst window (in ArcMap) – geoprocessing tools contained within ArcToolbox Network Analyst Software

Prepare the Feature Dataset and Sources –All Participating feature classes MUST be in the same Feature Dataset Prepare the Sources for Appropriate Roles –Direction, Miles, or Time Prepare Turn Feature Classes Create Network Dataset Using the Wizard Build the Network Creating a Network Dataset

Creating network data using wizard

Three types of network sources that participate in the creation of a network dataset: –Edge feature sources –Junction feature sources –Turn feature sources. Network Elements

Each feature class that participates in a network as a source generates elements based on its assigned role. –Line feature classes are used as a source for edge elements –Point feature classes are used to generate junction elements. –Turn elements are created from a turn feature class. Network Elements

1.Select the Source Workspace 2.Identify the Sources and the Role they will Play 3.Model Connectivity 4.Define Attributes and Determine their Values Designing a Network Dataset

Specifying network setup in wizard Model turns Connectivity Elevation data Cost – criteria for evaluating optimal route (e.g. often distance)

Cost –Measure and Model Impedances Descriptors –Describe Characteristics Restrictions –One Way Streets, No Pedestrians Hierarchy –Order Assigned to Network Elements Network Attributes

Field –Value from a Field (e.g. meters) Field Expression –Calculate Minutes - ([Miles] / [SPEED]) * 60 Constant –A Set Value VBScript – model complex attributes Network Evaluators

A network dataset has been created Now you can load your dataset into a Map Project.

This extension is composed of a number of parts: – wizard to create a network dataset (in ArcCatalog) – Network Analyst toolbar (in ArcMap) – dockable Network Analyst window (in ArcMap) –geoprocessing tools contained within ArcToolbox Network Analyst Software

Network Analyst Window Select/Move Network Location Tool Solve Directions Window Network Identify Build entire network dataset Create Network Location Tool Network Analyst Toolbar

Calculation options -Closest facility (gasworks park example) -Create optimal route (food delivery example)

Example: gasworks user area specify start and end points “facilities” are the start (circles) “incidents” are the end points of routes (squares)

facilities, the start (circles) Incidents, the end points (squares) e.g. gasworks park and home addresses

Resulting routes between facilities and incidents

View directions

Summary Stats

Used for batch Geoprocessing Model Builder Scripting –Python –Jscript –VbScript Network Analyst Toolboxes

Build network datasets Feature class to feature class conversion Common Problems in Feature Class Multiple street names Tips and Tricks

First and Foremost Form your Network Dataset: –Available from Commercial Vendors –Dataset comes with routing attributes so spatial analysis can be performed. –Construct Privately –Takes time, skilled labor, and information regarding geographic region Can buy or personally construct geographic region data

Network Dataset The logistics of a Network Dataset and how to manipulate it: –Usually one feature class with all geometrical data regarding streets –Polyline geometry -> vector data model –Format: Must be shapefile or a geodatabase feature class. If Not, then format using the Feature Class to Feature Class tool in ArcToolbox

Common Problems in Feature Class Multiple street names for one polyline 1 road labeled Hwy 4, University Way, and Main St Duplicate street names and Misspelling 2 independent polylines with same name Lack of endpoint connectivity Connected roads do not connect Lack of desired Field data/attributes Information regarding polyline attributes is not listed, such as paved or unpaved, toll road or not. Must join the remote attribute table to the field desired in working attribute table

Multiple Street Names Here one street ID is represented by four Names. The Network Dataset interprets this As if there are four streets at this one location. Assign a primary name to the street ID and then list the other names As secondary, tertiary, etc. This is done by placing the non-primary names In Fields labeled, Name1, Name2, Name3, etc.

Due to lack of creativity, some locations may have duplicate names. Beware: Upon running a Network Analyst tool such as Driving Directions, Optimal Route, etc. the tool may choose the wrong street with the same name. Use match to choose the correct one. Misspelling is a common error for street attributes, must edit personally. If the shapefile or geodatabase does not have endpoint connectivity then continuous roads may appear as dead ends. This will obstruct accurate spatial analysis of street class. –Can use the integrate tool in ArcToolbox to fix endpoint problems. –Also can use ArcEditor and run a Snapping program with a given tolerance to eliminate such problems. Multiple Street Names

Network Analysis allows you to perform a range of analytical functions such as optimal path analysis, route direction, and service area definition Difference between transportation (undirected) and utility (directed) networks Networks have a variety of elements, attributes and evaluators Designing and creating a Network Dataset requires defining sources, create connectivity, and assign attributes Take-home messages