In this lesson, you will learn about how risk and vulnerability assessments are used in public works planning.

Upon completion of this lesson, you will be able to:

• Define basic terms related to hazard analysis.
• Describe the role of public works in performing risk and vulnerability assessments.
• Describe the information that risk and vulnerability assessments can provide.
• Describe the process for conducting a hazard analysis.

In order to effectively plan for the hazards that may affect your community and your public works agency, it is important that you are familiar with the terminology related to hazard analysis.

These terms are covered in more detail in IS-556: Damage Assessment for Public Works.

Severity

Magnitude

Hazard

Risk

Vulnerability

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Severity

Severity is a measure of the seriousness of the effects of a hazard event. It can be measured by the number of people affected, amount of capital lost, number of buildings uninhabitable, and other factors. Certain systems may be inoperable and infrastructure could be destroyed.

Magnitude

Magnitude is a measure of the strength of a hazard event. The magnitude of a hazard is usually determined using technical measures specific to the hazard. For example, the United States uses the Saffir-Simpson scale, with a 1 to 5 categorization, to indicate the magnitude of hurricanes. This scale is based on the measure of a hurricane’s maximum sustained wind speed.

Hazard

A hazard is something that is potentially dangerous or harmful. It is often the root cause of an unwanted outcome. Hazards may be categorized as natural or as adversarial/human-caused.

• Natural hazards are caused by natural events that pose a threat to lives, property, and other assets. Examples include hurricanes, earthquakes, and tornadoes.
• Adversarial or human-caused hazards include technological hazards (caused by the tools, machines, and substances used in everyday life) and intentional acts (caused by people attacking or damaging what is valuable in a society). Examples include hazardous materials releases, major computer system failures (e.g., 911 system), terrorist attacks, and riots.

Risk

Risk is the possibility of loss or injury. More specifically, it is an estimated impact that a hazard would have on people, services, facilities, and structures in a community. It is the likelihood of a hazard event resulting in an adverse condition that causes injury or damage.

Risk is often expressed in relative terms such as a high, moderate, or low likelihood of sustaining damage above a particular threshold due to a specific type of hazard event. It also can be expressed in terms of potential monetary losses associated with the intensity of the hazard.

Vulnerability

Vulnerability is a description of how exposed or susceptible an asset is to damage. Vulnerability depends on an asset’s construction, contents, the economic value of its functions or services, and replacement/repair costs.

The vulnerability of one element of the community is often related to the vulnerability of another, and a hazard may cause indirect damages in addition to the damages that are caused by the direct impact. For example, many businesses depend on uninterrupted electrical power. If an electric substation is flooded, it will affect not only the substation itself, but a number of businesses as well. A refrigerated warehouse may lose its entire inventory and suffer severe economic losses as a result of the power failure. Often, indirect effects can be much more widespread and damaging than direct ones.

As used in this course, critical infrastructure and key resources (CIKR) are those systems and assets so vital to the community that their incapacity or destruction would have a debilitating impact on public services, security, economics, public health, or safety, or any combination of those matters. Critical infrastructure and key resources require special planning because they are necessary for the health and welfare of the whole population, and/or they represent high potential for loss or damaging effects on the community.

Some examples of critical infrastructure and key resources are listed below.

• Hospitals/medical centers/nursing homes
• Police and fire stations (public safety)
• Emergency Operations Centers (EOCs)
• Evacuation shelters
• Schools
• Nuclear power plants
• Dams and bridges
• Military installations
• Chemical plants
• Industrial facilities
• Water treatment and distribution
• Sewer treatment and collection
• Power generation and distribution
• Other

Though not the primary responsibility of the public works agency, participation by the agency in community-wide hazard analysis is essential to ensure consideration of the impact to public works roles and responsibilities.

Hazard analysis generally consists of two types of assessments:

• Risk assessment
• Vulnerability assessment

The public works agency must consider how specific public works facilities, infrastructure, or services may be affected by each hazard identified in the risk assessment to mitigate losses and to prepare for and respond to an incident.

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Risk Assessments

The risk assessment is the process of measuring the potential loss of life, personal injury, economic injury, and infrastructure and facility damage resulting from hazards such as natural disasters and technological/manmade hazards.

Vulnerability Assessments

The vulnerability assessment helps you evaluate how the hazards identified in the risk assessment could affect your community and the public works agency. It is an in-depth analysis of the services, building functions, systems, infrastructure, and site characteristics of the community to identify building weaknesses and lack of redundancy.

Vulnerability assessments also determine mitigations or corrective actions that can be designed or implemented to reduce the vulnerabilities and make the community more disaster-resistant and improve the capabilities of the public works agency.

When conducting the vulnerability assessment, the public works agency should consider questions related to each hazard, such as:

• How will flooding affect the need for evacuation?
• How will flooding affect critical infrastructure and key resources?
• How will strong winds affect overhead utilities (e.g., power lines)?
• How will debris disposal affect landfill capacity?
• How will warning capabilities affect public works response actions?
• How will the public works agency address the need for round-the-clock operations following an incident?

Remember that every community and every public works agency is different, so risk and vulnerability assessments will be community specific. These assessments can provide information about what hazards can occur, how often they are likely to occur, and how severe the situation is likely to get. They will also let your agency and community know how these hazards are likely to affect the community in terms of medical emergencies and damage to facilities and infrastructure.

When considering how the public works agency could be affected by each potential event, think about:

• Provision of services
• Resource needs
• Impact to infrastructure
• Cost considerations of response and recovery
• Identification of mitigation opportunities
• Debris removal and disposal issues
• Building and land use codes
• Environmental and sanitation impacts
• Traffic and transportation issues
• Evacuation and sheltering
• Public health

Kenneth Miller, Director of Public Works (retired), Village of Mundelein, IL:

It is important to have a list of what I would call “critical community components” that is agreed upon across the spectrum of your community or jurisdiction. These would be the highest priority items in buildings and facilities and services that need to be taken care of on a first basis. And that also, establishes a good starting point for getting your event and your response to any emergency or disaster off the ground.

Be prepared to make critical decisions on the best information available. Confirm the information when you can, but it is important to know that as time goes on, some of these decisions and some of the actions under way may have to be revised, because of new information and new confirmations. And don’t be afraid to do so. You can only work with what you have.

Understand that in any emergency, there really aren’t any absolutes. You really just have a quickly changing environment that you have to react to, make your decisions, and move forward. And this will continue, on and on. So be prepared for the long haul.

Gregg Varner, Director of Solid Waste (retired), County of Charleston, SC:

For us in public works, when we think about the idea of planning for a disaster, one of the things that jumps right out is that we in public works have got to look at things related to the risk for our community and the vulnerabilities that we have in the public works department. And the idea of risk, is just looking at those things that we might have, such as hurricanes, and then vulnerabilities for us is, what are the weaknesses that we in public works might have?

And I remember when hurricane Hugo was coming in, in 1989, I was the Public Works Director for the City of North Charleston and we’d never done anything like that—didn’t have the training, didn’t know what risk and vulnerability was all about. We discovered a few days before as we were trying to “button down the hatches,” I guess you might say, that our public works compound was actually in a flood zone and of course, had we done risk and vulnerability assessment, we’d have already known that and had planned for it.

So at the last minute we had to do some scampering around and get all of our equipment out of harm’s way so that we could protect the equipment and allow us to then respond after the hurricane came through so our lack of planning gave us an awfully good example of things that we hadn’t done right. Close

In order to identify hazards, create a list of the hazards that may occur in your community and surrounding communities. Use this list to focus on the most prevalent hazards in your area. These hazards could include:

• Avalanches
• Coastal erosion
• Coastal storms
• Earthquakes
• Extreme heat
• Floods
• Hailstorms
• Hurricanes
• Landslides
• Tornados
• Volcanoes
• Wildfires
• Windstorms
• Other hazards

To further focus your mitigation planning efforts, you must consider how the hazards may affect your community. Describe the characteristics of each event by considering what each hazard does and what happens in the community as a result. Use historical data, existing plans and reports, forecasts, and other information, to answer the following questions:

• How often is this hazard likely to occur?
• What happens as a result of this hazard (e.g., high wind, flooding, etc.)?
• Where is it likely to strike?
• How large an area is it likely to affect?
• How long can it be expected to last?
• What time of year is it more likely to occur?
• How fast is it likely to occur?
• Does a warning system exist, and how much warning time is there?
• What is the potential for cascading effects?

During the third step in the hazard analysis process, which is also known as developing a Community Exposure Profile, you will determine which assets in the community could be affected by the hazard and create a list of those assets. Assets include buildings and infrastructure such as critical facilities, natural resource areas, businesses, and residences.

This inventory of existing buildings (number, type, value) and estimation of potential loss following known hazards helps determine actions during the response period. Knowing areas of weakness helps focus resources, particularly on vulnerable populations and critical facilities, which could impact recovery.

The vulnerability assessment will help determine mitigation opportunities or corrective actions that can be designed or implemented to reduce the vulnerabilities and make the community more disaster resistant. Be sure to consult the Hazard Mitigation Plan for your community (which was likely created with input from public works) to help in completing your assessment.

During this step, create a map of assets in your community, focusing on those assets for which public works is responsible. Then, compare this asset map to the hazard map developed in the previous step to determine which assets could be impacted by each hazard.

Specify the areas most likely to be affected (e.g., the entire town, low lying areas, downtown, rural, highways). You can use a Geographic Information Systems (GIS)-based approach such as the Hazards U.S. Multi-Hazard (HAZUS-MH) software to map your community’s assets.

An overlay can be produced by hand using a light table or through the use of GIS. As shown in the image, a map showing the location of the community’s assets can be produced by overlaying the base map for the community with a map delineating hazard area boundaries. This will help you identify which structures are located in more than one hazard zone and which areas of the community or state are more or less susceptible to different hazards.

You can learn more about HAZUS-MH and GIS by visiting the links provided on the Resources page of the Toolkit.

Consider the implications for response and recovery, based on how the following areas are expected to be impacted by the hazards:

• Populations/Demographics
• Critical Infrastructure and Key Resources
• Buildings

Be sure to document all of your findings, keep track of the inventory data, and update the inventory regularly.

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Populations/Demographics

Including functional needs populations and locations is an important part of the community exposure profile. For each hazard, determine who could be impacted (e.g., all residents or certain neighborhoods/areas). If the hazard is likely to affect only certain areas, indicate those areas in the assessment so that resources can be allocated appropriately following a hazard.

Remember, some individuals may have additional needs before, during, and after an incident in functional areas. Knowing where these populations are located in your community is important so that additional measures can be taken as deemed necessary prior to and immediately following a hazard.

Information about populations and demographics (including geographic areas) could impact the provision of normal services of the public works agency, such as water, sewer, sanitation, etc. It could also impact disaster services provided by public works, such as debris removal. For example, if a mobile home community is hit by a tornado, there’s a significant impact to disaster services because of the need to haul away construction debris.

Critical Infrastructure and Key Resources (CIKR)

You must consider how each hazard could affect the critical infrastructure and key resources in your community. Remember, critical facilities are those that are necessary for the health and welfare of the population of your community. By including essential facilities, transportation systems, lifeline systems, high potential loss facilities, and hazardous material facilities as part of your community exposure profile, you can plan appropriate response and recovery actions to be implemented following a hazard and estimate resources needed.

Lifelines and infrastructure that should be considered include roads/streets, highways, services, potable water, and electrical systems. Keep in mind that damage to any of these systems could have severe detrimental effects to the community as a whole and to public works’ ability to provide routine services. For example a damaged bridge may prevent sanitation workers from accessing their routes to continue daily collection of household solid waste. Additionally, medical services, law enforcement, and firefighters may be unable to get to the people and places where they’re needed most.

Be sure to keep current information about critical facilities. Having a database of this information available will be useful when allocating resources following a hazard. You should have a list of the name and location of all critical facilities in your community. Other information kept on file should include the location of each facility (including GPS and/or National Grid System coordinates), contact information, and a note about any special response equipment that may be needed for that facility, especially related to the storage of any hazardous material.

This assessment of critical infrastructure and key resources will help you determine priorities for allocating resources or activation of additional resources so infrastructure can be restored quickly after a hazard event. It will also help you determine potential costs for responding to and recovering from the hazard event, as well as to identify mitigation opportunities.

Buildings

Determine what types of building (e.g., residential, commercial, and/or government) will be impacted by each hazard, and consider the implications. For example, if residential areas may be affected, the community may need more public shelters following a hazard event. Damaged commercial areas or government buildings may mean long-term economic or other impacts to the community.

Determine where volunteers and other personnel, such as those from state and federal agencies, will set up, and identify distribution centers and staging areas. Also be sure to establish an alternate Emergency Operations Center (EOC) in case it is damaged or inaccessible during or after an event, or in case your current facility may be too small to handle a large number of people during a serious event. 

The fourth step in the hazard analysis process combines the information from the previous steps to determine an estimate of expected losses from hazards. For the hazards you identified earlier that are most likely to affect your community, you should analyze losses in terms of people, economic impacts, environmental impacts, buildings, building contents, and other important assets.

To analyze the losses, you will determine the extent of the damages and then calculate the loss from each hazard event. Be sure that you have the most current property values when you perform this estimation. When performing this analysis, consider actual damage as well as cascading effects.

In this lesson, you became familiar with the hazard analysis process. You reviewed some basic terms and learned the four common steps for conducting a hazard analysis.

Remember, evaluating risks and vulnerabilities, especially to critical infrastructure and key resources, is the fifth step in the emergency planning process. The hazard analysis process is conducted within this step to provide valuable information through the risk and vulnerability assessments.

As a member of public works, you play an integral role in helping ensure that all necessary information is collected.