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Climate Change & Extreme Weather Vulnerability Assessment Framework

2 Defining Objectives and Scope

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This section provides suggestions and resources for articulating objectives, selecting and characterizing relevant assets, and identifying climate variables for study. Together, these steps frame the scope of the vulnerability assessment and drive the details required for the analysis. They form bounds to the study, minimizing data collection and analysis activities that would ultimately be extraneous to study objectives.

While we recommend articulating the objectives of the assessment as a first step, agencies may find it useful to simultaneously work to characterize relevant assets and identify climate variables to study.

2.1 Articulating Objectives

It is important to identify goals and objectives early in the vulnerability assessment process as they help determine the level of detail required in the analysis and the data and products that might be needed. When developing the objectives, consider the intended outcomes and target audiences. Objectives can be based on a range of activities or goals. Some questions to consider:

• What actions might be motivated by the assessment?
• Who is your target audience?
• What products are needed?
• How will they be used?
• What level of detail is required?

Example objectives include:

• Understanding the vulnerability of an agency's overall transportation system to climate change on a very general level.
• Informing the development and implementation of effective adaptation strategies.
• Integrating the vulnerability assessment into existing agency decision making processes.
• Planning for the siting or construction of new assets or services.
• Prioritizing among potential improvements or retrofits to existing assets.
• Implementing operational or design changes to mitigate climate vulnerabilities.
• Determining potential consequences from a particular type of climate impact, such as sea-level rise.
• Identifying segments or facilities at risk to climate change impacts.
• Understanding the scale and cost of climate impacts.
• Developing or augmenting data collection efforts about assets.
• Establishing or improving geo-spatial tools that can be used for transportation planning.
• Engaging stakeholders within the community or across other agencies.
• Educating transportation staff about potential risks posed by climate variability and climate change.
• Raising awareness among the public about activities to manage climate risks or efforts to bolster sustainability.

2.1.1. Examples from Practice: Articulating Objectives

Objectives deeply influence the scope and methodology of assessments. For example:

• The San Francisco pilot team's vulnerability assessment work was a part of the "Adapting to Rising Tides" (ART) project (www.adaptingtorisingtides.org), which is designed to increase the Bay Area's preparedness and resilience to sea level rise and storm events while protecting critical ecosystem and community services. The purpose of the project was to help the region's transportation and conservation planners improve vulnerability and risk assessment practices and to help formulate effective adaptation strategies. A goal of the project was to develop an approach for fostering local agency support and input on climate vulnerability and risk assessments. As such, the study team limited the study area for this initial effort a portion of one county, and limited the project scope to analyzing the impacts of sea-level rise and storm events. Many of the analysis steps involved efforts to engage stakeholders, consistent with the overall emphasis of the ART project on a collaborative planning process. The team developed detailed risk and vulnerability summaries for the most vulnerable ground transportation assets in order to inform the development of future adaptation strategies.
• The New Jersey pilot team's work represented a first step in a climate assessment for the various team members. Their project was designed to address a broad range of climate-related concerns. Their work is intended to be a platform for further assessment for other areas of New Jersey and their results will be used to engage a variety of transportation planners working at local, State, and regional levels. It included the compilation of a relatively comprehensive inventory of assets within two designated study regions, as well as the collection and analysis of a range of climate variables for the impacts analysis. The pilot team also helped to strengthen the partnerships among the agencies represented.
• The Gulf Coast Phase 2 study, which is being conducted by U.S. Department of Transportation (USDOT) in cooperation with the South Alabama Regional Planning Commission (SARPC), focuses on assessing vulnerability of Mobile, AL and developing analysis methods that can be replicated by other areas. The project also has a goal of enhancing regional decision makers' ability to understand potential impacts on specific critical components of infrastructure and to evaluate adaptation options. To this end, the study team has for the most part limited the project scope to methods and datasets that would typically be available in other study areas (with the exception of the climate information). The study team established a stakeholder group of local decision makers with which they regularly coordinate and narrowed the scope of assets for detailed study to those most important to the region.
• The Virginia Pilot study was led by researchers from the University of Virginia. The study team was interested in developing a decision support model that could be used by multiple areas, using Hampton Roads as a case study. They worked with the Hampton Roads Planning District Commission to test the model for real-world application. They have made their model available on a Web site at: http://www.virginia.edu/crmes/fhwa_climate/.

2.2 Selecting and Characterizing Relevant Assets

Transportation agencies need to decide which assets they wish to evaluate to meet the objectives of their assessment. Identifying the relevant assets for a vulnerability study and determining which characteristics of these assets to examine can help agencies narrow the scope of the vulnerability study. For example, if an agency would like to focus on a certain set of assets (e.g., owned or planned assets) it would begin the process by deciding which assets to include, assessing data availability for those assets, and understanding the timeframe and other important characteristics of managing those assets. When compiling this inventory, agencies should also gather any information that may help later to evaluate how resilient the asset is to climate stressors, and how costly damage to the asset or reductions in service could be. Example information types are provided below.

2.2.1 Asset Type

A wide range of asset types and system services could be considered in the assessment, depending on an agency's objectives. Transportation infrastructure such as roads, rails, and bridges will be a major focus for most agencies, but assets can also include support facilities, vehicles, and even ecosystem related assets for agencies interested in understanding how climate change will affect their environmental commitments or the ecosystem services on which the agency may rely. Some of the assets and systems that might be considered include:

• Bridges/tunnels
• Culverts/Storm sewers
• Road segments
• Key evacuation routes
• Rail lines, rail yards and intermodal transfer points, and passenger stations
• Transit system facilities and vehicles
• Bicycle and pedestrian facilities
• Port and airport infrastructure and access routes
• Maintenance and operations facilities
• Signals and traffic control centers
• Back-up power, communication, fueling, and other emergency operations systems
• Intelligent Transportation Systems (ITS)
• Signs and other roadside assets
• Pipelines and energy corridors
• Storm water management facilities
• Wetlands
• Floodplains
• Roadside vegetation
• Areas of potential rock fall

2.2.2 Temporal Scope

The study goals and audience may drive the temporal scope of the assets being assessed for vulnerability. If the target audience includes maintenance staff, then the study might focus on seasonal effects to existing assets. Alternatively, if the goal of the assessment is to help a metropolitan planning organization consider climate change effects in their long-term planning efforts, then it may be useful to include the future, planned assets that are in the long-range transportation plan in the universe of assets reviewed for vulnerability. In general, if the audience for the study is concerned about assets with long design lives (and planned upgrades) or assets envisioned for the future, it is important to include these assets in the analysis. For instance, the goal of the study may be to provide input to capital and rehabilitation cycles, so that new assets and upgraded assets incorporate needed adaptations.

2.2.3 Asset Data availability

Data availability can be a limiting factor on the inclusion of assets in the study scope. A variety of data is needed for climate vulnerability assessments, only some of which may be easily gleaned from standard agency databases. In some cases, necessary data may be in multiple databases or in different formats

and may require significant effort to merge the information into a usable format. Typical data that might be needed for a vulnerability assessment includes:

• Age of asset
• Geographic location
• Elevation
• Current/historical performance and condition
• Level of use (traffic counts, forecasted demand)
• Replacement cost
• Repair/maintenance schedule and costs
• Structural design
• Materials used
• Design lifetime and stage of life
• LiDAR (Light Detection And Ranging) remote sensing data
• Federal Emergency Management (FEMA) maps
• Floodplain and tsunami inundation zone maps
• Vegetation and soils surveys

2.2.4 Further Delineating Assets

In most cases, time and resource constraints prevent analyzing every asset in a transportation system. An important part of scoping the study, therefore, is finding a way to delineate which assets to examine. A number of different approaches have been used:

• Jurisdictional. Agencies may choose to limit the assessment to assets that are within their control (e.g., State-owned facilities for a State DOT analysis). Though less comprehensive, this can more directly inform future actions by the agency.
• Geographic. Specific areas may be more vulnerable to some climate effects. For instance, low lying areas are more vulnerable to flooding from sea-level rise or river flooding. Agencies might focus on these areas to quickly limit the analysis to the assets most likely to be affected by climate changes.
• Representative. An agency interested in understanding the range of impacts that might affect its system could select a small number of assets that represent the different types of infrastructure and assets found in its system.
• Historically poor performing or old infrastructure. Assets that are subject to frequent flooding and debris problems or old infrastructure with little design life left may be most vulnerable to the additional stressors imposed by climate changes.
• Most critical. Another approach is to identify the most critical elements of the transportation system for analysis, using quantitative or qualitative criteria. This provides a structured way to focus on the assets that are most important for the functioning of the transportation system. For instance, this approach might be taken if the objective of the vulnerability assessment is to understand the potential impact of climate change on the evacuation routes within a region. However, sometimes defining the most "critical" assets in a system can become politicized, as stakeholders may feel that their interests are not given sufficient priority. [See Section 2.3 for more information on conducting a criticality assessment.]

2.2.5 Examples from Practice: Selecting and Characterizing Relevant Assets

The pilot teams chose different ways of defining the scope of the assets to include. Many of these choices were related to the objectives of the overall analysis. In addition, these choices often reflected the jurisdictional boundaries of the agencies involved in the assessment or limits of the resources available. For example:

• The WSDOT Pilot team focused on transportation infrastructure that it owned, which included roads, rails, ferry terminals, and airports. They included assets already in place and funded projects (permitted and in final design), as opposed to proposed projects in transportation plans.
• The Virginia Pilot team performed analyses along four different dimensions of transportation planning, focusing on: existing assets, projects within the existing Long Range Transportation Plan, transportation analysis zones, and transportation policies.
• The San Francisco pilot team began with a list of almost 150 assets. These were narrowed down by combining assets (for example, including local streets with bike lanes and bus routes instead of looking at all three networks separately), eliminating assets that would not experience sea level rise under any of the anticipated scenarios, and ultimately focusing on representative and unique assets in the study area. These assets were evaluated to determine their specific risk and vulnerability, as well as, the risk and vulnerability of the system the asset was from. The team cited three reasons for deciding to use a set of representative and unique assets rather than a set of identified critical assets:
  • Most assets in the small study area were arguably important.
  • Determining importance would require data and detail beyond the budget and schedule of the project, and there was not enough background information on some of the facilities to perform an assessment of criticality.
  • They did not want to pass over assets that may not be "critical" but have intrinsic value to the region (such as recreational, commute or goods movement value).
• The New Jersey Pilot team conducted a detailed analysis using the statewide travel demand model to identify the zones with the greatest travel activity, and used that as a basis for determining critical corridors and assets throughout the study area.
• The Oahu MPO Pilot team used stakeholder input in a multi-day workshop to identify the areas and types of infrastructure that were considered high priority, and develop a list of five assets to focus on in subsequent analysis. The Pilot team identified several advantages of the stakeholder workshop method of identifying assets:
  • It accomplished multiple objectives in a short timeframe.
  • It helped accomplish the task with limited financial resources. Additionally, the pilot team was able to count the attendance of many workshop participants as in-kind match for Federal funding requirements.
  • It served as a method for technology transfer within the State of Hawaii and to other Pacific island nations.
• The Gulf Coast Phase 2 Study boundaries were limited to the Mobile, AL metropolitan area, a significantly smaller study area than phase one of the study. The smaller study area allowed for a more detailed analysis. The study focused on critical assets for each of six modes: highways, transit, rail, airports, ports, and land-based pipelines.

2.2.6 Resources for Selecting and Characterizing Relevant Assets

Assessing Criticality in Transportation Planning, FHWA 2011. This memo discusses approaches for narrowing the universe of transportation assets to study in a climate change vulnerability and risk assessment by assessing their "criticality" and otherwise narrowing study scope. It identifies common challenges, and draws on examples from the FHWA Adaptation Conceptual Model Pilots and the ongoing USDOT Gulf Coast Phase 2 study.

2.3 Assessing Asset Criticality

Performing a criticality assessment is one way to narrow assets for further study. It provides a structured way to identify the most important assets that an agency might wish to examine for vulnerability to climate change. Although useful, criticality assessments can be resource and data intensive. There are several approaches available for asset prioritization, falling into two broad categories (these general approaches can also be used to prioritize assets for reasons other than criticality):

Desk Review. One approach to formulating criticality criteria is to identify a broad range of criteria that capture use and access across a range of modes and systems. Assets are ranked based on data such as average daily traffic, functional classification, goods movement, emergency management, and expert judgment. Advantages of the approach include its transparency and replicability. However, lack of data on important elements of criticality, many of which are qualitative and locally specific, or not available from the private sector, could undermine results of the desk review in the eyes of the local stakeholders and decision makers. Moreover, the results are dependent on the weight applied to the various criteria; again, this weighting may not adequately capture local concerns.

Stakeholder Input. Determining asset criticality based on input from select stakeholders and local experts is a second approach to assessing criticality. With a stakeholder input approach, the project leaders will identify a group of stakeholders in the region with expert knowledge of specific interests (e.g., commercial activity, public safety, or road maintenance). The project leaders will then elicit feedback from these stakeholders on which assets are critical. Advantages of the stakeholder approach include getting buy-in from relevant stakeholders early in the process, encouraging collaboration and communication among stakeholders and actors likely to implement any adaptation strategies, accessing information that is not readily available in publicly-available datasets, and quickly assessing criticality without a lengthy research process. However, the results of the stakeholder -driven process are highly subjective, and the outcomes are dependent on the quality of the stakeholder engagement. For example, if project leaders decide to hold a workshop or series of workshops to solicit stakeholder feedback, the quality of the workshop facilitation, composition of workshop attendees, and level of participation from key experts will be important factors in the ultimate success of the stakeholder input approach.

Often, the two approaches are combined. Typically, a desk review will identify an initial list of critical assets based on commonly available data such as average daily traffic or economic information for the region (e.g., data on imports/exports from a particular port). The project team will then use the results of the desk review to inform and structure feedback from stakeholders and local experts.

2.3.1 Examples from Practice: Assessing Criticality

• The New Jersey pilot used the desk review approach. They developed a GIS based tool to conduct a "destination-based" criticality assessment, considering jobs, population density, average annual daily traffic, and ridership data. They note that their GIS criticality assessment tool "provides agencies with a robust platform to support smart decision-making, but it is not intended to substitute for the judgment and discretion of agency officials."
• The Oahu MPO pilot used the stakeholder input approach. They held a two-day multi-disciplinary workshop to identify five critical assets for further study.
• The WSDOT pilot also used the stakeholder input approach. In workshops around the State, WSDOT employees with local knowledge rated facilities for criticality on a ten-point scale. Note that while they developed criticality ratings, the WSDOT study assessed the climate vulnerability of all assets, not just those identified as critical. [See Figure 2]

Figure 2: WSDOT Criticality Rating Scale

• The Gulf Coast 2 project used a combined desk review and stakeholder input. A matrix of socioeconomic, operational, and health and safety characteristics of each potential asset was developed to "score" each asset for criticality. The scoring was done through a combination of quantitative measures and qualitative best judgment. A redundancy analysis was performed using the regional travel demand model to test the effect that losing particular links in the network had on congestion. The list of assets developed from this scoring system was supplemented with input from the study stakeholder group. The involvement of the stakeholder group was essential, since one of the lessons learned was that the "desk review" did not capture all the assets regarded as critical by local stakeholders. For instance, stakeholder input led to the inclusion of the Bayou La Batre port, home to a fishing and shrimping fleet with seafood processing facilities deemed important to the Mobile economy.

2.3.2 Criticality Assessment Resources

Assessing Criticality in Transportation Adaptation Planning, FHWA, 2011. This memo discusses approaches for narrowing the universe of transportation assets to study in a climate change vulnerability and risk assessment by assessing their "criticality" and otherwise narrowing study scope. It identifies common challenges, and draws on examples from the FHWA Adaptation Conceptual Model Pilots and the ongoing USDOT Gulf Coast Phase 2 study.

Assessing Infrastructure for Criticality in Mobile, AL: Final Technical Memo, FHWA, 2011. This memo summarizes the methodology and findings of Task 1 of the Gulf Coast Phase 2 study, which identified the transportation infrastructure components most critical to the Mobile region.

2.4 Identify Key Climate Variables to Study

An important first step to a vulnerability assessment is identifying which climate variables should be included in the study. Not all changes to the future climate will be significant to the local or regional transportation network, and limiting the study to the key variables of interest may allow for more in-depth projections of these variables. Section 3.3 includes more detailed information on developing climate information.

2.4.1 Key climate variables to consider

A range of future changes to the climate are of importance to transportation systems. Which ones are important to a specific transportation agency will vary by region and by study objectives. For transportation, the most important changes are often not changes to annual or seasonal averages, but to relatively short duration extreme events that can cause significant damage to transportation infrastructure or disrupt transportation operations. Examples of the kinds of climate changes included in transportation vulnerability assessments are broadly outlined below:

• Temperature. Temperature is projected to increase in almost every part of the country in the coming decades. For transportation, some impacts of interest might include increases in the number of very hot days, heat waves, changes to freeze-thaw cycles, and changes to the length of the construction season.
• Extreme Precipitation Events. Parts of the United States are projected to get wetter in the future while others will get dryer. However, many of the most significant transportation impacts will likely come from extreme precipitation events, which are projected to intensify. This poses flooding risks to roads, rails, maintenance facilities, and other assets, with below grade infrastructure such as tunnels, and poorly drained facilities being particularly vulnerable. Some areas will experience cycles of extended drought followed by extreme precipitation events which may destabilize vegetation along hillsides and increase the likelihood of rockfall.
• Sea-Level and Coastal Storm Surge. Sea-level is already rising along the U.S. coastlines, and the rate of sea-level rise is projected to accelerate over the coming century. This presents the risk of permanent or periodic inundation of coastal infrastructure as well as increased coastal erosion, rising groundwater levels and changes in salinity and it poses additional risks during storms by increasing storm surge heights as compared to today. In addition, coastal storms may intensify in the future, further increasing storm surge levels.
• Permafrost Thaw. In Alaska, much transportation infrastructure is built on permafrost foundations. Warming temperatures in the Arctic are already causing damage by thawing permafrost.
• Snowmelt Hydrology. Changes in winter snow accumulation, the timing and rate of spring snowmelt, and changes from a snow dominant to a rain dominant regime can cause an imbalance in the sediment transport characteristics of rivers, leading to flooding and channel instability problems for transportation infrastructure that is built alongside or crosses rivers.

2.4.2 Selecting climate variables to study

The climate variables selected will most likely be influenced by agencies' experiences regarding the system's performance in the past in response to the local weather, especially during extreme weather conditions such as high winds, heat waves, flooding caused by heavy precipitation or coastal storms, or drought. Examining transportation system performance during historic weather events can aid in understanding the sensitivity of the transportation system to weather extremes and aid in selection of the climate variables and thresholds to examine in the projections, providing information that can be used to gauge impacts associated with future climate conditions.

An assessment of past weather-related disruption and damage may consider:

• Weather related sources of disruption to transportation services.
• Transportation assets currently affected by weather extremes.
• Damage to roads or bridges, or supporting infrastructure (e.g., culverts).
• Thresholds at which the system begins to experience impacts (e.g., a specific high temperature or a peak flow rate that has led to damage or failure).
• Locations within the system that experience impacts.

The historical information can provide a foundation from which to identify future vulnerabilities and the climate variables/thresholds that should be addressed in the projections. For example, if heat waves pose problems for transportation systems or assets, then the model projections for temperature during the spring, summer, and fall months should be investigated closely (increases in winter temperatures are unlikely to result in "heat waves" for most locations). A specific variable to consider might be the frequency of days over 95 degrees Fahrenheit in the future, which might affect restrictions on construction or operations work crews, or perhaps information on likely exceedances of the temperature threshold applied in a particular materials specification or guidance.

While these thresholds should inform the variables for which projections are run, it is also important to be mindful of the potential of climate effects previously experienced rarely, if at all. For instance, in coastal areas it may make sense to consider projections of sea-level rise even if sea levels or tides have not been a concern in the past. [See section 3.4 for additional discussion of climate sensitivity.]

2.4.3 Options for Obtaining Climate Information

One consideration in determining what climate variables to look at may be the availability of future climate data for your study area, given the resources at your disposal. Information on projected changes in climate can be obtained in several different ways, including:

• Refer to existing climate information developed by others, like the Unites States Global Change Research Program (USGCRP),that is relevant at broad geographical scales, as noted above. Preliminary questions on potential impacts may be answered by referring to broader regional reports on changes in climate.

• Use climate data that has already been downscaled to your area for other studies. Some States and metropolitan areas have developed downscaled climate data for State or city climate action plans. These data can then be used for a more detailed transportation analysis.

• Work with climate modelers to develop projections tailored to your needs. This can be a resource intensive approach, but can be used to generate detailed information for your analysis. (This approach is discussed further in the Analysis section below.)

• Use information that is being used for other studies in your State or region in order to be consistent and reduce stakeholder confusion. For example, California has established sea-level rise guidelines, as have Florida and the US Army Corps of Engineers (USACE).

Transportation agencies may want to partner with other groups that have experience developing or using climate projections. Useful sources of information and assistance include:

• State Climatologist - In some States, the State climatologist may be able to provide information on current climate research projects and existing projections that you could use that are relevant to your study region.
• University climate research centers located in your region may already be doing research on regional climate projections, and may be able to provide available data or be interested in partnering on your research effort.
• State and local environmental or other agencies may be able to help provide or develop necessary data. For example, local agencies may have access to LiDAR data or other data relevant to coastal mapping.
• Experts in the area who can offer advice or assistance in developing projections.
• Federal agencies such as NOAA, USGS, USACE that have data, modeling, historic weather data, and future climate predictions.
• The emergency response community who have been dealing with and planning for regular all hazards events; people whose knowledge and expertise of short term events can be extrapolated into long term climate change possibilities.

2.4.4 Examples from Practice: Identifying Climate Variables for Study

The differing objectives of the pilot studies resulted in a range of approaches:

• The San Francisco pilot limited its climate variables to sea level rise, storm surge and wind-driven wave effects. Storm event impacts are already being experienced with the San Francisco Bay, and future stronger and more frequent storms is likely to be the most burdensome, near-term climate change impact to the region. The study selected sea level rise scenarios for mid- and end-of-century that were within the range of values included in the State of California Sea‐Level Rise Interim Guidance Document (October 2010). The two sea level rise scenarios were evaluated for three tide/Bay water level conditions (mean higher high water, the 100-year extreme water level, and the 100-year extreme water level with wind-driven waves) by leveraging regional modeling results from the USGS and FEMA.
• The Gulf Coast 2 study examined temperature, precipitation, sea-level rise, and storm surge variables. New, downscaled projections of temperature and precipitation for the study area were developed for the study. Several temperature and precipitation values were chosen to be projected, including a range of annual, seasonal, and extreme values [see Table 1]. Sea level rise scenarios were developed based on literature reviews of global sea-level rise scenarios and an assessment of historic subsidence/uplift rates specific to the area, and hurricane scenarios were developed using historic storms as a base source of data.
• The Oahu MPO pilot looked at potential sea-level rise, storm surge, wind, high intensity rainfall, drought, and temperature effects on critical assets on the island of Oahu. The study made use of climate projections from published literature and storm surge modeling from University of Hawaii research conducted for FEMA.
• The New Jersey pilot looked at sea-level rise, storm surge, extreme temperatures and temperature ranges, extreme and average precipitation, drought, and inland flooding. The pilot benefitted from assistance from their State Climatologist, and hired a consultant to develop downscaled climate projections for the study area. The pilot also analyzed future floodplain expansion using a regression model developed in a FEMA-sponsored study. Inputs to the model included current and future climate variables.
• The WSDOT pilot considered all known climate threats in the Pacific Northwest: sea level rise, precipitation change, temperature change, and fire risk. The study used climate projections funded and endorsed by an act of the Washington State Legislature for use in adaptation studies, developed by the University of Washington Climate Impacts Group.
• The Virginia pilot considered sea-level rise, storm surge, extreme temperature events, and enhanced precipitation.

Table 1:

Climate Variables Used in the Gulf Coast Phase 2 Study

2.4.5 Resources for Identifying Key Climate Variables

Regional Climate Change Effects: Useful Information for Transportation Agencies, FHWA 2010. This document provides basic information on projected future climate change effects over the near term, mid-century and end-of-century by U.S. region.

The Use of Climate Information in Vulnerability Assessments, FHWA 2011. This memorandum focuses on the use of climate information when performing a vulnerability assessment. The memorandum includes discussion of using historical climate information and includes information on potential data sources.