lect e 3lecture 3lect e 3lecture 3 network analysis geog406geog406--network analysisnetwork...

Lect e 3Lect e 3Lecture 3Lecture 3

Network AnalysisNetwork Analysis

Geog406Geog406--Network AnalysisNetwork Analysis

OutlineOutlineNetwork Network AnalysisAnalysisGIS and Transportation PlanningGIS and Transportation PlanningGIS and Transportation PlanningGIS and Transportation PlanningLinear Reference Linear Reference SystemSystemSt i R t A l i /LiSt i R t A l i /LiSteps in Route Analysis/Linear Steps in Route Analysis/Linear

ReferencingReferencing


Network AnalysisNetwork AnalysisNetwork AnalysisNetwork Analysis

Used to represent and Used to represent and analyze cost, time, delivery analyze cost, time, delivery and accumulation of and accumulation of resources along networks.resources along networks.resources along networks.resources along networks.

Need for Need for management/tools to use management/tools to use and maintain networksand maintain networksand maintain networks.and maintain networks.

Common Networks:Common Networks:Common Networks:Common Networks:–– Roads, powerlines, Roads, powerlines,

telephone cables, etc…telephone cables, etc…



3 Common 3 Common problemsproblems analyzed using analyzed using networks:networks:

Route SelectionRoute SelectionRoute SelectionRoute SelectionResource/Territory AllocationResource/Territory AllocationTraffic ModelingTraffic Modeling



Route SelectionRoute Selection–– Identify Identify bestbest route based on route based on

a set of criteria.a set of criteria.–– Ex. Find the shortest, Ex. Find the shortest,

quickest or least costly quickest or least costly route.route.

–– Traveling Salesman Problem: Traveling Salesman Problem: Least cost tour through a set of nodes so that each node is visited exactly onceis visited exactly once.

–– The closest facilityThe closest facilityThe nearest hospitalThe nearest hospitalThe nearest schoolThe nearest school


The nearest schoolThe nearest school


Resource AllocationResource Allocation–– Distribution of networks to Distribution of networks to

centers.centers.centers.centers.–– TerritoriesTerritories are assigned to are assigned to

one or more one or more allocation allocation centerscenters in a network.in a network.

–– All routes pursued, not just All routes pursued, not just least cost route.least cost route.

–– The service area: The areas The service area: The areas ithi t i di tithi t i di twithin certain distance or within certain distance or

time from facilitiestime from facilities–– Ex. School districts may use Ex. School districts may use

resource allocation to assignresource allocation to assign


resource allocation to assign resource allocation to assign neighborhoods to schools.neighborhoods to schools.


T ffi M d liT ffi M d liTraffic ModelingTraffic Modeling–– Streets represented by interconnected arcs and Streets represented by interconnected arcs and

nodesnodesnodes.nodes.–– Attributes associated with arcs define travel speed Attributes associated with arcs define travel speed

and direction.and direction.

Travel costsTravel costs

–– Traffic is placed in network and movement modeled.Traffic is placed in network and movement modeled.

–– TimeTime–– DistanceDistance

R i iR i i l dl dGeog406Geog406--Network AnalysisNetwork Analysis

–– Restrictions: oneRestrictions: one--way streets, closed streets, way streets, closed streets, prohibited turnsprohibited turns

Applications of GIS in Applications of GIS in ppppTransportationTransportation

DatabaseDatabase–– Roads, routes, stop signs, accidents,Roads, routes, stop signs, accidents,Roads, routes, stop signs, accidents, Roads, routes, stop signs, accidents,

pavement, constructionpavement, construction

RoutingRoutingRoutingRouting–– Which route is the bestWhich route is the best

Transportation PlanningTransportation PlanningTransportation PlanningTransportation Planning–– Traffic prediction/modelingTraffic prediction/modeling



CCCentersCenters–– A set of connected features in a networkA set of connected features in a network–– May be centers of demand, supply or both.May be centers of demand, supply or both.

Network LinksNetwork LinksNetwork LinksNetwork Links–– Connect and provide paths between centers.Connect and provide paths between centers.

Transit CostsTransit Costs–– “Price” of moving a resource through a segment of a network. i.e. “Price” of moving a resource through a segment of a network. i.e.

ti di t t it i thfi di l ithti di t t it i thfi di l ithtime, distance, monetary units using pathfinding algorithms.time, distance, monetary units using pathfinding algorithms.


Linear Referencing SystemLinear Referencing SystemLinear Referencing SystemLinear Referencing System

Defined: The method of storing geographic Defined: The method of storing geographic locations by using relative positions along a locations by using relative positions along a measured linear feature. measured linear feature. Example: route IExample: route I--10, Kilometer 23.10, Kilometer 23.


Linear Referencing SystemsLinear Referencing SystemsLinear Referencing SystemsLinear Referencing Systems

ApplicationsApplications–– Collecting data along linear features such Collecting data along linear features such

as roads, rivers, and railwaysas roads, rivers, and railways–– Managing pavement qualityManaging pavement quality

b k db k d–– Managing urban networks and inventories Managing urban networks and inventories such as street signs, traffic lights, such as street signs, traffic lights, pedestrian crossings bicycle paths curbspedestrian crossings bicycle paths curbspedestrian crossings, bicycle paths, curbs, pedestrian crossings, bicycle paths, curbs, and sidewalksand sidewalks

–– Managing railroad track qualityManaging railroad track quality


g g q yg g q y


Reference systemsReference systems–– Geographic reference systemGeographic reference systemGeographic reference systemGeographic reference system–– Grid referencing systemGrid referencing system–– NonNon--coordinate reference systemcoordinate reference systemNonNon coordinate reference systemcoordinate reference system

–– Locations are coded with a twoLocations are coded with a two–– Locations are coded with a two Locations are coded with a two dimensional X, Y coordinate systemdimensional X, Y coordinate system

–– Examples: (10 20) (103 5 2 3)Examples: (10 20) (103 5 2 3)Geog406Geog406--Network AnalysisNetwork Analysis

Examples: (10, 20), (103.5, 2.3)Examples: (10, 20), (103.5, 2.3)


Geocoding: The process of assigning a location, usually Geocoding: The process of assigning a location, usually in the form of coordinate values (points), to an address in the form of coordinate values (points), to an address by comparing the descriptive location elements in theby comparing the descriptive location elements in theby comparing the descriptive location elements in the by comparing the descriptive location elements in the address to those present in the reference material.address to those present in the reference material.


Linear Reference SystemLinear Reference SystemLinear Reference SystemLinear Reference System

A collection of routes can be stored in a A collection of routes can be stored in a feature classfeature classExample: a set of bus routes in a cityExample: a set of bus routes in a cityDynamic Segmentation:Dynamic Segmentation: The process of The process of computing the map locations of events computing the map locations of events stored and managed in an stored and managed in an event tableevent table using using

li f i t tli f i t ta linear referencing measurement system a linear referencing measurement system and displaying them on a map.and displaying them on a map.


BREAK

Linear Reference SystemLinear Reference SystemLinear Reference SystemLinear Reference System

Route:Route:–– A route is a linear feature A route is a linear feature

that has a unique identifier that has a unique identifier and measurement systemand measurement systemand measurement system and measurement system stored with itstored with it

–– Routes measurements are Routes measurements are stored with its geometrystored with its geometry

–– (X, Y, M) (X, Y, M) X Y d M b iX Y d M b i–– X, Y and M can be in X, Y and M can be in different measurement different measurement unitsunits


Route LocationRoute LocationRoute LocationRoute Location

A route location describes a portion of A route location describes a portion of a route (line) or a discrete (point) a route (line) or a discrete (point) ( ) (p )( ) (p )location along a route.location along a route.–– A linear route location: From .. To…A linear route location: From .. To…A linear route location: From .. To…A linear route location: From .. To…

Example: Mile 2 to mile 4 on the IExample: Mile 2 to mile 4 on the I--10 10

–– A point location: a single measurementA point location: a single measurementp gp gMile 4 along IMile 4 along I-- 405405


Route LocationRoute LocationRoute LocationRoute Location

ArcMap Find tool ArcMap Find tool can be used to find can be used to find either point or either point or linear route linear route locationslocationslocationslocations


Route Event TablesRoute Event TablesRoute Event TablesRoute Event Tables

Tables to store route locations and their Tables to store route locations and their attributesattributesEvents tables are organized based on Events tables are organized based on common themecommon theme–– Speed limitsSpeed limits–– Year of surfacingYear of surfacing

P t C ditiP t C diti–– Present ConditionPresent Condition–– SignsSigns–– AccidentsAccidents


AccidentsAccidents

Route Event TablesRoute Event TablesRoute Event TablesRoute Event Tables

At least two columns:At least two columns:–– An event KeyAn event KeyAn event KeyAn event Key–– Measure location(s)Measure location(s)

Can be one column: location along the route Can be one column: location along the route Ca be o e co u ocat o a o g t e outeCa be o e co u ocat o a o g t e outewhere the event occurswhere the event occurs

–– Point Event TablePoint Event Table

O it b t l FROM TOO it b t l FROM TOOr it can be two columns: FROM, TOOr it can be two columns: FROM, TO–– Line Event TableLine Event Table


Point Event TablePoint Event TablePoint Event TablePoint Event Table


Line Event TableLine Event TableLine Event TableLine Event Table


Steps in Route AnalysisSteps in Route AnalysisSteps in Route AnalysisSteps in Route Analysis

1.1. Create a route feature classCreate a route feature class22 Calibrate route dataCalibrate route data2.2. Calibrate route dataCalibrate route data3.3. Display and query route eventsDisplay and query route events

Edit t d tEdit t d t4.4. Edit route dataEdit route data


Create and Convert Route Create and Convert Route DataData1.1. Create route feature class from Create route feature class from

scratchscratchOROR

11 Convert an existing shapefileConvert an existing shapefile1.1. Convert an existing shapefile, Convert an existing shapefile, coverage or feature class to route coverage or feature class to route feature classfeature classfeature classfeature class


Create Route From Create Route From ScratchScratch

Route data can be Route data can be stored instored in–– ShapefilesShapefiles–– CoveragesCoverages–– FeaturesFeatures

New routes can be New routes can be dd d t th tdd d t th tadded to the empty added to the empty

route feature classroute feature class–– DigitizingDigitizing

Con e ting selectedCon e ting selected–– Converting selected Converting selected features in a layer to features in a layer to routes and add the routes and add the routes to the empty routes to the empty route dataroute data


route dataroute data

Converting Existing Line Converting Existing Line g gg gFeatures to Route DataFeatures to Route Data

–– Features in the line Features in the line layer should be layer should be assigned a route IDassigned a route IDassigned a route IDassigned a route ID


Calibrating Route DataCalibrating Route DataCalibrating Route DataCalibrating Route Data

Improve accuracy of the distance measurement– Calibration points

Mil diMil di–– Mileage readingMileage reading

10.5 16.5

00

1510

20 280

22 5

30


0 22.5

Calibrating Route DataCalibrating Route DataCalibrating Route DataCalibrating Route Data

Calibration WizardCalibration Wizard–– Calibration points Calibration points

are stored in a point are stored in a point layerlayer

–– Mileage readingMileage readingMileage readingMileage reading


Manual CalibrationManual CalibrationManual CalibrationManual Calibration


Route EventsRoute EventsRoute EventsRoute Events

Point Event TablePoint Event Table–– Accident, signsAccident, signs–– RouteID, MilieageRouteID, Milieage


Line Event TableLine Event TableLine Event TableLine Event Table

Line Event tableLine Event table–– Speed limit, Surface Speed limit, Surface

material, traffic material, traffic volumevolume

–– Route ID FromMRoute ID FromMRoute ID, FromM, Route ID, FromM, ToMToM


Add Route EventsAdd Route EventsAdd Route EventsAdd Route Events


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