By: Elise Fisher

Organization: EF Geographic. L.C.

Brief Explanation: Uses GIS to assess expected response times from each of their existing public safety agency

locations. From the results of this analysis, response personnel tasked with planning and maximizing resources can

easily identify how different neighborhoods will be affected by changes in service levels. Public safety agencies can then

make decisions about how to adjust staffing and equipment to maximize the effectiveness of available resources. This

case study involves a Fire Department.

Department Background: This example is

based on Toledo, OH. Same methods can

be applied to any size department.

Size:

� Small

� Medium

X Large

GIS Ability:

� None

� In House

X Consultant

Data Needed:

• a. Fire Station – preferably a GIS file, but an Excel, text, or dbase file will do with a little extra work.

o Station Number – Text

o Physical Address - Text

o ZIP - Text

o Apparatus, including type - Text

o Individual Apparatus staffing, including medic levels, if EMS calls will be modeled - Integer

• Street Network – Routable – Topologically correct

o Necessary fields:

� Segment length - Double

� Speed - Integer

o Optional Fields

� One Way based on direction of segment travel, populated with to-from (TF) and from-to (FT)

indicators - Integer

� To-from elevation, populated with standardized values - Integer

• Fire Response Areas

o Station Number, Text

Alarm Configurations

Software Required:

• ArcGIS (ArcView)

• Network Analyst

Skills to perform tasks (i.e. Network Analysis, GIS Data editing, etc.):

• Assess GIS data and fields

• Open and close ArcGIS ArcView and ArcCatalog

• Add data into ArcView

• Assess data in ArcCatalog

• Create a Address Locator

• Geocode addresses. Ie., fire stations to street file, if necessary

• Import text data into geospatial format, if necessary

• Create and build a Street Network

• Create Service areas based on travel times using Network Analyst

• Modify and calculate in ArcGIS tables, if necessary

• Ability to label features in ArcView

• Symbolize data in ArcView

• Cartographically represent service areas and fire stations in an organized map.

Response Time Analysis

Field Operations Guide

CARAT - Field Ops Guide

Procedure:

• Prep the Street file for Network creation

o Determine and verify units of length field, typically feet

o Determine and verify units of speed, typically MPH

o If using one-way segments, verify and/or create fields for one directional travels costs [TF_COST] AND

[FT_COST]

o Calculate travel cost, if your data contains one-way identifiers.

� Select: "ONE_WAY" = 'FT'

• If feet, Calculate: [FT_COST] = ((( [Length]/5280)/ [MPH])*60), for length in feet

• If miles, Calculate: [FT_COST] = (( [Length]/ [MPH])*60), for length in miles

• Non-FT values (all other records), Calculate: [TF_COST] = -1

� Select: "ONE_WAY" = ' TF'

• If feet, Calculate: [TF_COST] = ((( [Length]/5280)/ [MPH])*60), for length in feet

• If miles, Calculate: [TF _COST] = (( [Length]/ [MPH])*60), for length in miles

• Non-TF values (all other records), Calculate: [FT_COST] = -1

� Select all other records (two-way street segments), "ONE_WAY” = ' '

� If feet, Calculate: [FT_COST] = ((( [Length]/5280)/ [MPH])*60), for length in feet

� If miles, Calculate: [FT_COST] = (( [Length]/ [MPH])*60), for length in miles

� If feet, Calculate: [TF_COST] = ((( [Length]/5280)/ [MPH])*60), for length in feet

� If miles, Calculate: [TF _COST] = (( [Length]/ [MPH])*60), for length in miles

. *At this point all values for TF_COST and FT_COST should have a value >0 or -1. There should be

no 0s.

• Identify the elevation fields and not the meaning of the values.

• Close ArcView

• Open ArcCatalog

• Create a Street Network in ArcCatalog

o Right-click on the streets file name, select ‘New Network Dataset’

o Name the ‘New Network Dataset’ something that makes sense to you, click ‘Next’

o Make sure the connectivity is set to ‘End Point’, click ‘Next’

o Use elevation fields if available, click ‘Next’

o Select ‘Yes’ and check the box for Global Turns, click ‘Next’

o Change the ‘Unknown’ ‘Units’ of ‘Cost’ units to ‘Minutes’

o Highlight the ‘Cost’ line, and click the ‘Evaluators’ button. Make sure the newly created FT_COST and

TF_COST fields are being used for the ‘Values’. Click ‘Constant’ for ‘Element’ ‘Turn’ and select ’Global

Turn Delay’. Click the ‘Evaluators Properties’ button. Uncheck the ‘Only Show Turn Categories for Local

Roads’, click ‘OK’, click ‘Apply’, click ‘OK’,

o ‘Unknown’ ‘Units’ for ‘Oneway’ ‘Name’ is ok. click ‘Next’, click ‘Next’, click ‘Finish’, click ‘Yes’ to build the

network.

• If fire stations do not currently exist in a GIS format, create a GIS layer by geocoding against the street file, from

a text or Excel file.

o Create an ‘Address Locator’ from your street data.

� In ArcCatalog navigate to the directory where the street are stored (they should appear in the

main window, not in the Table of Contents.

� Right-click in the main window and select ‘New’, ‘Address Locator’. If your fire station table

contains ZIP Codes, select ‘US Streets’. If your fire station talbe does not contain ZIP Codes,

select ‘US Steets with Zone’.

� Rename your Address Locator, ‘Name: “

� Navigate and Select your street file.

� Select all corresponding street fields.

CARAT - Field Ops Guide

o Click ‘Tools’, ‘Geocoding’, ‘Address Locator Manager’, click ‘Add’, navigate to your newly created

Address Locator.

o Open ArcView

o Click ‘Tools’, ‘Geocoding’, ‘Geocode Addreses’, select your non-geographic Fire Station table, and select

your ‘Output shapefile or feature class:’ Click ‘OK’.

o The Fire Station layer will appear in the Table of Contents. Symbolize the Fire Stations. The layer table

with include all the attributes in your text or Excel file. staffing

• Create Service Areas

o If you didn’t need to geocode your fire station, add the geographic Fire Station GIS data and symbolize

as you see fit.

o Add in the new ‘Street Network Dataset’

� Select ‘New Service Area’ from the ‘Network Analyst’ menu.

• A new ‘Service Area’ will appear in your Table of Contents.

• A ‘Network Analyst Window’ will also show up to the right of the Table of Contents

window.

� Set properties for the Network Service Area generation.

• Right-click ‘Facilities’ in the ‘Network Analyst Window’ to ‘Load the Facilities’ in the

‘Network Analyst Window’. Select ‘ Load Locations’. Select your Fire Station file from

the pull down menu. Select the attributes you’d like to view in the window for the ‘Sort

Field’ and the ‘Property’ ‘Name’ ‘Field’. Typically this is the station number. Click ‘OK’.

The Fire Stations will appear in the window. Expand the ‘+’ button next to the ‘Facilities’

in the ‘Network Analyst’ window, if the list doesn’t expand and you’d like to see the

stations.

CARAT - Field Ops Guide

• At this point you may start setting the properties for your ‘Service Area’. Right-click

‘Service Area’ in the TOC and select ‘Properties’. Click on the ‘General Tab’ rename the

‘Service Area’ to something a little more useful.

o Click on the ‘Analysis’ tab and make sure your ‘Impedance’ is set to ‘Cost (Minutes)’. Enter the ‘Service

Area’ (travel time) you would like to create in the ‘Default Breaks:’ window. Let’s start with a ‘4’ as the

‘Default Breaks:’ value. ‘Direction:’ should be set to ‘Away from Facility’. U-turns can be set at your

discretion. Typically, they are set to ‘Nowhere’. Please make sure the ‘Oneway’ box is checked. The

‘Default Breaks:’ window controls the analysis measure (minutes) of the ‘Service Area’. It will be

changed based on the desired analysis measure. Ie., 4-minutes, 8-minutes, 10-minutes of travel time.

• Click on the ‘Polygon Generation’ tab. Un-check the ‘Generate Polygons’ box.

• Click on the ‘Line Generation’ tab. Check the ‘Generate Lines’ and the ‘Generate

Measures’ boxes. Select ‘Overlapping’.

CARAT - Field Ops Guide

• Click on the ‘Accumulation’ tab and check the ‘Cost’ box.

• Click on the ‘Network Locations’ tab and verify the ‘Facilities’ have been set to ‘Location

Type:’. The rest of the defaults should work.

• Click ‘OK’. The ‘Service Area’ properties menu will close.

� Solve the for the 4-minute travel time of all the fire stations.

• Click the ‘Network Analyst’ ‘Solve’ button or right-click the ‘Service Area’ in the Table of

Contents and select ‘Solve’.

o The 4-minute ‘Service Area’ lines will appear in the Table of Contents under your ‘Service Area’, ‘Lines’.

At this point you should copy them to your computer. They are currently only temporary. Right-click

‘Lines’ ‘Data’ ‘Export Data’, select a directory, name and save.

• Repeat the steps above to calculate the 8-minute ‘Service Area’.

• Create 4 & 8-Minute Response area maps.

4-Minute Response Area

CARAT - Field Ops Guide

8-Minute Response Area

*Warning some pre-constructed station locations may not be close enough to the street network to be routed. Moving

the station locations closer to the street network (be very careful) allows them to be included in the routing.

Additional Resources for performing Response Time Analysis

Tutorial on modeling street networks

GIS For Fire Station Locations and Response protocols, An ESRI Whitepaper