Network analysis in gis

NETWORK ANALYSIS
Swapnil R. Rajput
Roll No:19 , M.tech 1st year

WHAT IS NETWORK ?
 Network is a set of connected lines
 Network can represent rivers , roads, waterlines ,
telecommunication lines etc.
 Networks can be Directed and Undirected / planer and
non-planner.
 In GIS Networks are widely used for two kinds of
modeling.
Transportation network
Utility network

TRANSPORTATION NETWORK:
 Undirected networks.
 edge on a network may have a direction assigned to it,
the person or resource being transported is free to
decide the direction, speed, and destination of
traversal. example-person in a car travelling on street.

UTILITY NETWORK:
 Directed network
 Path is predetermined
 It can be change but not by agent.
The electricity flows around the circuit and lights the bulb

 In ArcGIS ,Transportation network modeled
using network dataset.
 For Utility Dataset in ArcGIS modeled using
geometric dataset.

NETWORK ANALYSIS:
 Network analysis analyze the way ‘goods’ can be
transported along these lines (telecommunication lines ,
road etc)
Example: undirected roads.
 Network analysis can be done in raster or in vector.

TYPES OF OPERATION:
 Shortest path analysis
 Best Route
 Closest facility
 Allocation
 location-Allocation
 OD-cost matrix
 Network-partitioning

SHORTEST PATH ANALYSIS:
 Shortest path analysis finds the path with the
minimum cumulative impedance between nodes on a
network. The path may connect just two nodes an
origin and a destination or have specific stops
between the nodes.
(1) (2) (3) (4) (5) (6)
(1) ∞ 20 53 58 ∞ ∞
(2) 20 ∞ 39 ∞ ∞ ∞
(3) 53 39 ∞ 25 ∞ 19
(4) 58 ∞ 25 ∞ 13 ∞
(5) ∞ ∞ ∞ 13 ∞ 13
(6) ∞ ∞ 19 ∞ 13 ∞
Fig: Link impedance matrix values between cities on a road network.

BEST ROUTE:
 Whether finding a simple route between two locations
or one that visits several locations, people usually try
to take the best route. But "best route" can mean
different things in different situations.
 Best route can be the quickest, shortest, or most
scenic route, depending on the impedance chosen.
 Impedance  time, distance.

We uses time as an impedance. The quickest path is shown in blue
and has a total length of 4.5 miles, which takes 8 minutes to
traverse.

We choose distance is chosen as the impedance. Consequently, the
length of the shortest path is 4.4 miles, which takes 9 minutes to
traverse.

Along with the best route, ArcGIS Network Analyst provides
directions with turn-by-turn maps that can be printed.

CLOSEST FACILITY:
Closest facility finds the closest facility, such as a hospital,
fire station, or ATM, to any location on a network.

ALLOCATION:
 Allocation measures the efficiency of public facilities,
such as fire stations, or school resources, in terms of
their service areas.
Figure:
Service areas of two fire stations within a 2-minute response time.

LOCATION-ALLOCATION:
 Location-allocation helps you choose which facilities
from a set of facilities to operate based on their
potential interaction with demand points.

OD-COST MATRIX:
 OD cost matrix is a table that contains the network
impedance from each origin to each destination.

NETWORK PARTITIONING-TRACE
 Trace analysis is performed when we want to
understand which part of network is ‘conditionally
connected’ to a chosen node on the network ,known as
trace origin.

REFERENCES:
 http://webhelp.esri.com
 Geographic Information System, Kang-tsung
Chang, fourth edition Tata McGraw-Hill.
 Spatial data analysis by Ms. Vandita Srivastava
IIRS Dehradun,India
 ArcGIS 10 help

Network analysis in gis

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Network analysis in gis