By Author(s): Don Oliver [3]
Published Tuesday, November 1, 2011 | From the November 2011 [4] Issue of FireRescue [5]

It has been said many times that information is power. This is never truer than when providing fire and rescue protection to a community. Many of today’s fire service leaders, both in uniform and in laboratory coats, are working to develop tools that help firefighters cope with the unique challenges of the modern fire service. The safety of response personnel is their number one priority.

Geographic information systems (GIS) allow you to identify and quantify community hazards and values at risk. In this article, I’ll introduce the elements of a GIS-based community fire risk and hazard assessment, and discuss how you can start using GIS in your risk assessment and preplanning.

Assessment Elements
Many studies have been published on the subject of fire risk and hazard modeling; however, little has been done to describe how GIS can assist in modeling the relationship between hazards, risks and values.
A GIS-based community fire risk and hazard assessment consists of four elements:

1. Identifying/classifying community hazards.
2. Identifying risk factors, potential and probability.
3. Identifying/classifying community assets/values.
4. Fusing all of the elements into a visual display of the existing hazards: their potential impact on values and the risk or likelihood of an unwanted event.

The result of the assessment enables fire officers to quickly see and understand community values at risk. Plans can then be developed with specific actions targeting the highest-priority fire protection and life safety problems.

Hazards
A GIS-based community fire risk and hazard assessment starts with identifying, ranking and mapping identified hazards.

You must first decide how you will identify the locations of certain hazards. For example, you can identify individual buildings, technological hazards or natural hazards, or group hazards within larger geographic areas. I recommend grouping hazards geographically; examples include block groups, zoning areas, zip codes, fire demand zones and census tracts. Zoning areas often provide a good hazard boundary, as there are similar kinds of land use and building construction types within them. The hazard boundary will be the primary boundary for the other assessment elements (risk and value).

In assigning hazards within the selected area, the hazard rating is determined based on the predominance of the hazard in the area. Example: A geographic area that consists largely of wood-frame structures or modern lightweight construction would receive a high hazard rating even though some of the structures may be different. If an area consists of numerous hazardous materials, or other dangerous conditions (CBRN), it may drive up the overall assigned hazard rating for the area. If there’s a small number of significant technological hazards within a fire protection hazard boundary, rating these individual locations with a higher hazard rating may be appropriate.

For significant natural hazards (flammable wildland/urban interface areas, seismic zones, areas exposed to historical weather events, etc.), you may need to create a separate natural hazard boundary area. The result: a fire and rescue protection hazard boundary for structural fire and rescue exposures and a separate natural hazard boundary based upon natural hazards and the areas they may impact. A natural hazard boundary is depicted as a separate GIS layer, and it may overlay one or more fire/rescue protection hazard boundaries.  

But why create two overlapping yet separate hazard boundaries? Doing so allows you to:

• Develop fire protection mitigation and response plans targeted toward normal fire response/rescue operations.
• Focus on large-scale emergency response, where mutual aid and multiple days of operations and logistical support are required.
• Look at both structural fire/rescue data and the potential impacts from a large-scale emergency together, which in turn allows you to understand the major impacts and potential secondary impacts.

How We Identify Hazards
Wilson (N.C.) Fire/Rescue Services (WF/RS) uses GIS to map out every commercial structure in the city and to plan out inspections. Fire crews perform the pre-incident surveys and inspections to document vital information useful in an emergency response to the building. In addition, photos are captured to show all outside views and any special considerations inside of structures (see p. 44). The information shows the shape, size, location and condition of all the city buildings, as well as the water-supply system and any built-in fire protection systems that may be utilized during an incident.

All this data is then catalogued and stored in the GIS. Buildings are put into color-coded categories based on potential danger. For vacant buildings, we rate their condition and plot their location. Categories of vacant buildings range from structurally sound and secured to abandoned/dangerous. Firefighters can look at individual building plans and maps, or they can get a macro-level view showing multiple building locations and their corresponding color category designation.

We’ve also expanded building-specific data collection to address rapid collapse potential. Buildings with lightweight construction, engineered structural support members, heavy fire loading or trussed roof or floor systems are identified and uniquely symbolized in the Rapid Collapse Consideration GIS layer.     

As for emergency planning for hurricanes, floods and other natural disasters, WF/RS culls information from multiple sources, including 100-year and 500-year flood plan models. Once a major incident unfolds, WF/RS has all the information needed to plan a response, evacuate people and maintain situational awareness.

Of course, building a GIS risk/hazard system isn’t a one-time thing. We use ArcGIS desktop software for planning annual building inspections, including vacant commercial buildings. Firefighters must be able to access current information, such as the building floor plan, the types of materials used in the building construction, the type of sprinkler system in place and whether there are hazardous materials stored inside.

Once you’ve identified each fire/rescue protection or natural hazard boundary—or individually rated structure—document the rationale for the ranking, along with any unusual circumstances or considerations.  

Risks & How We Identify Them
Risk will be assigned based upon the predominance of risk for the zone and is calculated based on historical incidents, zoning and use patterns and, for natural hazards, the history of the hazard causing emergencies and predicted likelihood of another.

Typically, a minimum of three years of fire history should be used; for natural hazards, going back 50 or 100 years is more appropriate. Risk rating (low, medium, etc.) is relative and can be assigned based upon the department’s preference. Considerations for risk may include:

• Homeless activity in abandoned buildings
• Older construction, due to electrical system/heating system failures
• Arson patterns
• Activity—welding, grinding, etc.
• Areas where children play (playing with matches)
• Variables associated with land use, including population density (metro, urban, suburban, rural); demographics, such as socioeconomics, population age, cultural characteristics; and zoning (commercial, public, residential, industrial, etc.)

Risk rating for natural hazards is based upon the likelihood of the event occurring. In some cases, flooding may already be classified as a 50-, 100- or 500-year event. Other natural hazard events (earthquakes, tornados, blizzards, etc.) may be more difficult to predict, but every effort should be made to include them.

To identify and assign risk, maps of incidents involving fire, motor vehicle accidents and EMS are brought in from Wilson County’s Computer Aided Dispatch (CAD) and records-management systems and geo-coded daily. This allows us to examine recent trends, as well as historical incident trends, by geographic area over several years. The volume, type and frequency of incidents help determine the level of risk. Land use patterns and zoning are also important considerations.  

Note: Identifying risks has nothing to do with the consequence of the incident should it occur; this is covered in the hazard rating and will also be considered when values are assessed. Once risk has been assigned, document the rationale for the assigned risk rating and save the risk ranking as a new GIS layer.

Community Assets
Values that are important to the community range from those that provide essential services to those that sustain local community economic needs or historic community icons. Values include:

• Commercial buildings, which are important for the economic vitality and sustainability of the community.
• Government buildings or facilities, which are important for the continuity of government operations and services.
• Cultural values or iconic values, such as historic buildings, cultural centers, etc.
• Public occupancies, or large locations where an event could injure several people (stadium, apartments, etc.).
• Churches, schools, hospitals, senior citizen facilities, etc.
• Buildings that house utilities services

It may be most effective to simply rate a qualifying asset (value) as high with everything else being considered moderate as opposed to providing an area ranking. In other words, an asset is either a critical value or not. After values are identified and viewed based upon their degree of exposure to hazard and risk, this may be sufficient to identify priorities.

Completing the Assessment
The final step in the assessment is combining or fusing the hazard, risk and value layers to understand specific values at risk or community vulnerability. Turning on the hazard, risk and value layers will provide a visual display of critical community values at risk. Critical values within very high-hazard fire protection zones with a high risk rating would take priority for mitigation and preplanning.

Obviously, there will be numerous combinations of values exposed to various levels of hazard and risk. It is the jurisdiction’s preference as to how they will be prioritized and what actions (if any) should be taken. This will be discussed in the planning phase. All of the critical values, their degree of exposure to hazards and the risk of an event (fire, CBRN, natural emergency) will be displayed.

How We Use the Information
From a general perspective, each fire protection zone should be examined to determine if current fire protection is adequate or if additional actions are necessary, such as:

• Are current response capabilities adequate to meet fire protection response time standards?
• Does a potential CBRN event pose a threat to a large number of citizens?
• Are fire demand requirements adequate to meet high-value protection requirements?
• Are critical values sufficiently protected or are they at risk of experiencing a large-scale natural disaster?
• Are fire incident types within a fire protection zone with high values showing a pattern? Are mitigation actions necessary (fire prevention education, fire regulation compliance and enforcement, etc.)?
• Are additional pre-fire plans for high values needed?
• Are training drills or exercises necessary to raise preparedness for a large-scale emergency?

These fire protection zone actions or fire protection prescriptions can be documented, prioritized and linked through the GIS map for reference, progress monitoring or other administrative needs. Complex fire protection circumstances and additional resource needs for priority protection requirements can be visually presented in an easy-to-understand way. Appropriate maps can be printed to help illustrate why certain problems take priority and why additional funding and resources are required. This information is also used for a variety of daily operational needs.WF/RS staff uses these maps of incident trends to determine if resources—such as fire companies, truck companies or rescue squads—should be moved from one fire station service district to another location.

In addition, WF/RS has a GIS-based executive dashboard, designed by the Omega Group, that brings together multiple tabular and geospatial files into one single, comprehensive view that’s used for resource allocation and management. Recent events, such as inspections, EMS calls and fire responses, are viewable in the form of reports, maps and charts.

For tactical daily use, mobile data terminals located in fire trucks show digital maps and data as soon as personnel enter a truck to respond an emergency. Digital street maps show the exact location of the incident. Maps and related tabular information help firefighters see aerial photos, possible hazardous materials, hydrant locations, electric lines, water supply and more. All of this information allows personnel to quickly ascertain the situation and possible incident potential as they’re arriving on scene.

A Final Word
Few fire departments have the luxury of a full-time GIS analyst, and in many cases we are far behind our city colleagues in employing GIS data. But those factors can actually work to your advantage.

For example, WF/RS works closely with the city of Wilson’s GIS analyst, who is assigned to the fire department three days a week. The cooperation yields significant results. An enterprise Esri system was already in place at the city when we first began using ArcGIS, so we were able to immediately begin using information housed by other departments, including spatial data for streets, water lines and hydrants, electrical and gas lines, and building and zoning specifications. We combined this data with our data, including fire stations, apparatus locations, service area boundaries, types of incidents and more. Coordination is key; all departments must be able to share their data and access other department’s data.

GIS technology is making a significant difference in our industry. It’s being used now more than ever for critical decision-making. It is exciting and encouraging that our profession is creating a safer environment for our firefighters and citizens. Remember: Information is power.

Key Concepts
To conduct a successful community fire risk and hazard assessment, you must first understand a few definitions:
Hazards are known physical features that can ignite and sustain combustion, or existing features (natural or manmade) that have the potential to cause negative impacts to life, property and/or natural resources.
Risks are human behavior, systems malfunctions, an event that results in an ignition or other detrimental incident that results in negative impact to life, property and/or natural resources.
Values are community assets, including life, property and natural resources.

Hazard Assessment Criteria
Fire/rescue hazards include physical features that can ignite and sustain combustion. Hazard ratings are based upon resistance to control; construction type is a primary driver. For example, rating or ranking of hazards could be assigned as follows:
Low—Structures that consist of mainly fire-resistive or noncombustible materials
Moderate—Structures that consist of an ordinary mix of construction materials
High—Structures that consist of significant wood-frame or heavy timber materials
Very High—Structures with combustible materials that share walls, attics, etc.
Moderate to Extreme—Technological or hazmat exposure (CBRN)

GIS Data to Assess Risk
The data that will be required for risk assessment may include:

• Historic fire incidents by cause (geo-coded from fire RMS or CAD system)
• Historic law enforcement incidents by type (geo-coded from law enforcement RMS or CAD system)
• Historic emergency incidents
• Street layer
• Water system supply and water points (hydrants)
• Utilities (gas, electric, fiber, etc.)
• Parcel
• Zip code boundaries
• Building footprints
• Hazardous materials permits
• Block groups/demand zones
• Census tracts
• Building and safety data
• Socioeconomic informatio

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