Geographical Information Systems Geographical Information Systems (GIS)(GIS)

for Public Safety Applicationsfor Public Safety Applications

NC EMToday 2000NC EMToday 2000

Pressley Lorbacher

William E. Ott

Scott Roberts

Mike Smith

Joseph Zalkin

What is GIS?What is GIS?

Geographic Information Systems In the strictest sense, a GIS is a computer system

capable of assembling, storing, manipulating, and displaying geographically referenced information , i.e. data identified according to their locations. Practitioners also regard the total GIS as including operating personnel and the data that go into the system.

How does GIS work?How does GIS work? A GIS, which can use information from many different

sources, in many different forms can help with such analyses. The primary requirement for the source data is that the locations for the variables are known.

Location may be annotated by x,y, and z coordinates of longitude, latitude, and elevation, or by such systems as ZIP codes or highway mile markers. Any variable that can be located spatially can be fed into a GIS.

Several computer data bases that can be directly entered into a GIS are being produced by Federal agencies and private firms. Different kinds of data in map form can be entered into a GIS.

How does GIS work?How does GIS work?

A GIS can also convert existing digital information, which may not yet be in map form, into forms it can recognize and use. For example, digital satellite images can be analyzed to produce a map like layer of digital information about vegetative covers.

Likewise, census or hydrologic tabular data can be converted to map-like form, serving as layers of thematic information in a GIS.

GIS BuzzwordsGIS Buzzwords

Shape FilesLayersGeocodingNetworking

Data CaptureData Capture How can a GIS use the information in a map?How can a GIS use the information in a map?

If the data to be used are not already in digital form, that is, in a form the computer can recognize, various techniques can capture the information.

Maps can be digitized, or hand-traced with at computer mouse, to collect the coordinates of features.

Electronic scanning devices will also convert map lines and points to digits.

Global Positioning System (GPS) surveying and input from stationary receivers or mobile AVL systems.

Data capture - putting the information into the system - is the time-consuming component of GIS work. Identities of the objects on the map must be specified, as well as their spatial relationships.

Data SystemsData Systems

GIS data can be accumulated in a variety of ways, including:

GPS (most accurate method of exact incident location)

AVL - GPS Manual address keying into a data system which is

then ‘geocoded’ to the GIS system

Projection and RegistrationProjection and Registration A property ownership map might be at a different scale from a soils

map. Map information in a GIS must be manipulated so that it registers, or fits, with information gathered from other maps. Before the digital data can be analyzed, they may have to undergo other manipulations - projection conversions, for example - that integrate them into a GIS.

Projection is a fundamental component of mapmaking. A projection is a mathematical means of transferring information from the Earth's three-dimensional curved surface to a two-dimensional medium - paper or a computer screen. Different projections are used for different types of maps because each projection is particularly appropriate to certain uses. For example, a projection that accurately represents the shapes of the continents will distort their relative sizes.

Projection ExampleProjection Example

Data ModelingData Modeling

It is difficult to relate flood plain maps to rainfall amounts recorded at different points such as airports, television stations, and high schools.

GIS, however, can be used to depict two- and three-dimensional characteristics of the Earth's surface, subsurface, and atmosphere from information points.

Info Retrieval, Modeling, and NetworkingInfo Retrieval, Modeling, and Networking

What do you know about the swampy area at the end of your street? With a GIS you can "point" at a location, object, or area on the screen and retrieve recorded information about it from off-screen files.

Using scanned aerial photographs as a visual guide, you can ask a GIS about the geology or hydrology of the area or even about how close a swamp is to end of a street. This kind of analytic function allows you to draw conclusions about the swamp's environmental sensitivity.

In the past 35 years, were there any gas stations or factories operating next to the swamp? Any within two miles and uphill from the swamp? A GIS can recognize and analyze the spatial relationships among mapped phenomena. Conditions of adjacency (what is next to what), containment (what is enclosed by what), and proximity (how close something is to something else ) can be determined with a GIS.

Info Retrieval, Modeling, and NetworkingInfo Retrieval, Modeling, and Networking

If all the factories near a wetland were accidentally to release chemicals into the river at the same time, how long would it take for a damaging amount of pollutant to enter the wetland reserve?

A GIS can simulate the route of materials along a linear network. It is possible to assign values such as direction and speed to the digital stream and "move" the contaminants through the stream system.

This same ‘networking’ process can be applied to public safety response data, thus allowing ‘best route’ type planning to be done for given areas, units, times of day, days of week, or any combination of these

Data Output = InformationData Output = Information

A critical component of a GIS is its ability to produce graphics on the screen or on paper that convey the results of analysis to the people who make decisions about resources.

Wall maps, mapbooks, and other graphics can be generated, allowing the viewer to visualize and thereby understand the results of analyses or simulations of potential events.

Application of GISApplication of GIS

Mapmaking (cartography)Site Selection (stations, command posts,

etc..)Emergency Response PlanningSimulation of environmental effects or

impact of events (chemical spill, spraying, flooding, etc..)

Coordinate SystemsCoordinate Systems There are many basic coordinate systems familiar to

students of geometry and trigonometry.

These systems can represent points in two-dimensional or three-dimensional space.

René Descartes (1596-1650) introduced systems of coordinates based on orthogonal (right angle) coordinates.

These two and three-dimensional systems used in analytic geometry are often referred to as Cartesian systems.

Similar systems based on angles from baselines are often referred to as polar systems.

Coordinate SystemsCoordinate Systems The most commonly used coordinate system today is the

latitude, longitude, and height system. The Prime Meridian and the Equator are the reference planes

used to define latitude and longitude. The geodetic latitude (there are many other defined latitudes)

of a point is the angle from the equatorial plane to the vertical direction of a line normal to the reference ellipsoid.

The geodetic longitude of a point is the angle between a reference plane and a plane passing through the point, both planes being perpendicular to the equatorial plane.

The geodetic height at a point is the distance from the reference ellipsoid to the point in a direction normal to the ellipsoid.

Coordinate SystemsCoordinate SystemsUniversal Transverse Mercator - UTMUniversal Transverse Mercator - UTM

Universal Transverse Mercator (UTM) coordinates define two dimensional, horizontal, positions.

UTM zone numbers designate 6 degree longitudinal strips extending from 80 degrees South latitude to 84 degrees North latitude.

UTM zone characters designate 8 degree zones extending north and south from the equator.

There are special UTM zones between 0 degrees and 36 degrees longitude above 72 degrees latitude and a special zone 32 between 56 degrees and 64 degrees north latitude.

Each zone has a central meridian. Zone 14, for example, has a central meridian of 99 degrees west longitude. The zone extends from 96 to 102 degrees west longitude.

Eastings are measured from the central meridian (with a 500km false easting to insure positive coordinates).

Northings are measured from the equator (with a 10,000km false northing for positions south of the equator).

Geodetic DatumsGeodetic Datums

Referencing geodetic coordinates to the wrong datum can result in position errors of hundreds of meters. Different nations and agencies use different datums as the basis for coordinate systems used to identify positions in geographic information systems, precise positioning systems, and navigation systems. The diversity of datums in use today and the technological advancements that have made possible global positioning measurements with sub-meter accuracies requires careful datum selection and careful conversion between coordinates in different datums.

Earth SurfacesEarth Surfaces

GIS SoftwareGIS Software

ESRI ArcInfo / ArcView plus many add in modules

ESRI is the market leader and gold standard within the government and engineering communities

Other vendors offer competing products, which combined make up less than 15% of the GIS market

GIS Software CostsGIS Software Costs

$8,000 and up for full GIS system$1,000 and up for GIS modeling only. This

is what the typical public safety agency would need if their local government has a GIS system that can feed map data to analyze with response data

GIS Hardware CostsGIS Hardware Costs Full blown GIS will need a server, Oracle, SQL

Server, DB2, etc.. as a repository. This easily can be $15,000 to $20,000.

GIS and GIS modeling will need workstations, faster is better, LARGE screen monitors. This would run in the $1,500 to $4,000 range.

Color printers / plotters for maps. Pricing from $200 up to tens of thousands of dollars.

Public Safety Specifics for Public Safety Specifics for GISGIS

Plotting and analyzing call patternsPlotting and analyzing best response

patterns (no more pins in maps) Determining positioning for unitsModeling of hazard areas..ties to a reverse

911 system to allow for automated evacuation notification in emergencies, etc..

Data Drives DecisionsData Drives Decisions

Garbage In - Garbage OutA Thing Seldom Looked for is Seldom

FoundNew LocationsHistorical DataPre-Planning

Public PerceptionPublic Perception

Response Time Saves Lives– Where– When– How Long

Multi-unit Response Configurations

PlanningPlanning

PERMITS for FACILITIESSpecial Services Locations

– Dialysis – Woman’s Clinics– Free Standing Care Facilities (Cath Labs)

Durham Durham North CarolinaNorth Carolina

County covers 299 Square MilesCity covers 95 Square MilesTotal County Population – 235,000Total City Population - 178,000

EMS Responses by UnitEMS Responses by Unit19991999

County Units

Medic 30 - 198 Medic 40 - 675 Medic 50 - 504 Medic 60 – 1,305 Medic 70 – 592

City Units

Medic 1 - 3,067 Medic 2 - 2,530 Medic 3 - 3,755 Medic 5 - 4,057 Medic 6 - 3,759 Medic 8 - 2,332

Calls by AreaCalls by Area

City North - 9,217City South - 12,133

County North - 1,247County South - 1,173

GIS MappingGIS Mapping

TB Cases 1999 (19)Stabbings - Year to Date 2000 (60)Gunshots - Year to Date 2000 (130)Homicides - Year to Date 2000 (25)

Geographical Information Geographical Information SystemsSystems

Using GIS to Plan and Make Changes in the way EMS Serves Their Local Community

Durham County EMS System

An Actual Project

Real Life GISReal Life GIS

Defining Change

How Does the Public Evaluate the EMS System?

How Do Public Officials Evaluate the EMS System?

As an EMS Administrator How Do You Evaluate Your System?

Response Times!

Response Times!

Response Times!

Data Has to Be Consistent.Data Has to Be Accurate.You Have to Know What You Want to

Measure.

Measuring Data for Use in Geographical Information Systems

Garbage In Garbage Out

Defining ChangeDefining Change

What Problems Did We Face in Our System?Why?What Should We Do to Fix These Problems?

27,000 Annual Call Volume6 Paramedic Units in the City6 Paramedic Units in the County Fire

Stations From 7 A.M. To 7 P.M.City Fire Operates 21 First Responder

Units From 12 Stations

Durham County EMS

Measured All Emergency Responses Where Patient Contact Was Encountered in a Three Month Period of Time. (5123)

Recorded Response Times in Excess of 8 Minutes From Dispatch to Arrival in the Same Given Period of Time. (109)

What Does This Data Tell You As an Administrator?

A Picture Is Worth a Thousand Words

or Approximately

$ 600,000 !

Now As Administrators What Does

This Picture Tell You?

What did the picture identify?What did the picture identify?

Definite Need for Southwest Paramedic Coverage.

Inner City Call Volume Was Greater Than the Number of Available Paramedic Units.

Calls in the County That Were in Excess of 8 Minute Response Times Were at Night When the Paramedic Coverage Was Discontinued.

What did we do ?What did we do ?

Placed a Paramedic Unit in the Southwest Portion of Durham Utilizing a City Fire Station.

Expanded Paramedic Coverage in the County Fire Stations to 24 Hours.

Implemented Three (3) City Fire Department EMT-Intermediate Transport Units in the Inner City Districts to Back-up the Inner City Paramedic Units When They Are Occupied.

County EMS Contracted With Parkwood EMS to Provide Paramedic Service in the South / Southwest Area of Durham With 2 Paramedic Units.

Questions – CommentsQuestions – Comments

Please see the GIS mapping Please see the GIS mapping displays around the roomdisplays around the room

Thank You!Thank You!