Department of Geography and Urban Studies, Temple University GUS 0265/0465 Applications in GIS/Geographic Data Analysis

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Department of Geography and Urban Studies, Temple
UniversityGUS 0265/0465Applications in
GIS/Geographic Data Analysis
Lecture 4 Network Operations
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Features of a Road Network
Link Impedance weights on an link Turn
Impedance time it takes to complete a turn at a
given node Turn Table table listing turn
options and impedance for each node One way or
closed streets Overpasses and Underpasses
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Road Network Operations
Address Geocoding Shortest Path Analysis Closest
Facility Allocation Location-Allocation
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Road Network Operations
Address Geocoding Takes an address in text form
and assigns it a geographic coordinate location
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Address Geocoding
Left_from Left_to Right_from Right_to
Street_name Type Left_Zone Right_Zone 201
299 200 298
SUNSET ST 92374 92373

209 Sunset St. 209 House number Sunset Street
name St. Type 92374 Zone
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Road Network Operations
Shortest Path Analysis Finding the shortest path
(in travel cost, not just distance) between two
locations on the network. Djikstras
Algorithm. http//www.unf.edu/wkloster/foundati
ons/DijkstraApplet/DijkstraApplet.htm
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Shortest Path Analysis
Traveling salesman problem Given a number of
stops, find the shortest route that begins at a
given location and ends at the same
location. http//riot.ieor.berkeley.edu/cander/c
s270/
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Road Network Operations
Closest Facility Finds the closest facility to a
given location on a network. Essentially, a
multiple shortest path analysis among the given
location and each in a set of candidate
facilities. The facility with the shortest path
is the closest.
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Road Network Operations
Allocation Allocating a region in space to a
point facility. For example, allocating urban
areas to fire districts based on proximity to the
nearest fire station. Each station is allocated
a given area.
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Allocation
Shaded area indicates areas within 2 minutes of a
fire station
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Road Network Operations
Location-Allocation Finding a location for a
point location on a network to maximize some
allocation criteria. For example, given the
criteria that all areas must be within 2 minutes
of a fire station, where should another fire
station be built?
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Road Network Operations
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Road Network Operations
Allocation
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Road Network Operations
Location-Allocation
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Road Network Operations
Location-Allocation
Minimum distance model minimizes the total
distance traveled from all demand points to their
nearest supply centers Maximum covering model
maximizes the demand covered within a specified
time or distance
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Dynamic Segmentation
allows for the representation of routes along a
network. was developed to store important network
locations that are georeferenced based on their
distance along the route from some starting
point. For instance, many transportation
agencies store geographic information that is
georeferenced to mileposts along a highway.
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Dynamic Segmentation
Tables Route Table each record is an individual
route (a path along the network) with links to
individual sections Section Table each record is
an individual section linking a route to its
component links Event Table each record is a
thing that exists along the route, e.g. a
stretch of pavement quality, a bridge location,
etc. Arc Attribute Table each record is an arc
(table automatically generated by Arc/Info for
vector topologic data structure)
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Dynamic Segmentation
Route table
Section table
Roads AAT
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Dynamic Segmentation
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Dynamic Segmentation