Developing a Highway Framework to Conduct an All-Hazards Risk and Resilience Analysis (2023)

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11   C H A P T E R 3 To successfully integrate risk and resilience into all facets of a transportation agency’s activities, it is important to have a comprehensive framework. There are many frameworks for risk and resilience assessments for multiple sectors. After studying multiple risk and resilience frameworks during the literature review phase, the research team developed a risk and resilience framework building on the most comprehensive and used frameworks, includ- ing the AASHTO’s framework from the Transportation Management Guide to incorporate risk management into TAMP, the FHWA Vulnerability Assessment and Adaptation Framework, the risk management framework from the International Organization of Standardization (ISO) 31000, and the RAMCAP Plus framework among others. The enhanced framework is presented in Figure 3-1 and consists of four modules: (1) organization, (2) scoping, (3) assessment, and (4) management. An overview of each module is provided. 3.1 Organization Before a transportation agency can begin a risk and resilience analysis of its system, it must first answer key questions: (1) what are the organization’s resilience vision, mission, and goals and (2) what is the organization’s risk tolerance? To design for resilience, engineers need to know what to design. Having clear definitions for risk and resilience will help agencies achieve their mission and goals. Defining a risk threshold or target is the first step. To define a risk threshold, it is helpful for an agency to consider its mission, values, goals, objectives, and definitions for risk and resilience. • Mission and Vision Statements. A business mission statement is a simple action-oriented statement that explains the purpose of the business. The mission statement of the U.S. DOT is “. . . to ensure our Nation has the safest, most efficient and modern transportation system in the world, which improves the quality of life for all American people and communities, from rural to urban, and increases the productivity and competitiveness of American workers and businesses.” Mission statements for state DOTs typically follow a similar vein, explaining their purpose of providing mobility to the traveling public with added emphasis on safety, efficiency, sustainability, and reliability. A transportation agency’s vision is its picture of how an improved transportation system in the future can enhance the economy and quality of life for the communities it serves. Vision statements are based on trend analyses of change in land use, demographics, population, economics, climate change, and so on. Goals and objectives are derived from the vision statement. It is key that risk and resilience be incorporated into agency mission and vision statements because these statements represent the initial step for successfully incorporating risk and resilience efforts into the different agency areas. • Goals and Objectives. The vision statement encompasses one or more goals, for example, safety and reliability. Objectives are the outcomes of pursuing a goal, and the success of an objective is assessed with performance measures. If safety is the goal, then fewer accidents are the objective, Risk and Resilience Framework

12 Developing a Highway Framework to Conduct an All-Hazards Risk and Resilience Analysis and the performance metric is the percentage reduction in accident rates. If reliability is the goal, one objective could be maintaining roadways in good working condition. The performance measure is the percentage of lane miles maintained to a targeted condition. Similarly, resilience should be incorporated into the agency’s goals and objectives, and risk and resilience metrics should be developed to measure whether these goals and objectives are achieved. • Standard Definitions. How DOTs define risk and resilience determines performance mea- sures and investment priorities. For example, suppose risk is defined as an adverse event’s impact on a physical asset. In that case, the metric might be the percentage loss of asset replacement value, and the priority in investment is to harden the asset. On the other hand, if resilience is defined in terms of the ability of an asset to rebound from an adverse event, the metric could be restoration time, and the investment priority is to build redundancy or enhance emergency response (see the literature review in Appendix B for more discussion of risk and resiliency definitions). 3.2 Scoping Risk and resilience assessment begins with identifying a system’s exposure to one or more threats. What is the spatial extent of the threat? Within that spatial extent, what assets are exposed? In addition, how critical are the exposed assets to the network? • Threat and Asset Characterization. Threat characterization includes developing a portfolio of hazard models or maps that accurately reflects the intensity and likelihood of threats within the agency’s area of responsibility. Figure 3-1. Risk and resilience framework.

Risk and Resilience Framework 13 • Threat-Asset Pair Selection. Agencies develop the threat-asset matrix to show what assets are exposed to what threats and prioritize risk management decisions. With physical threats, deciding what are the important threats can be assisted with Geographical Information System (GIS) tools to intersect hazard maps with geospatial representations of physical assets. With non-physical threats, expert opinion and wargaming may be employed. • Criticality Assessment. Criticality is the relative importance of an asset within the overall transportation system to the agency’s larger goals and objectives, which are providing equitable access to a reliable transportation system. Common variables used by state DOTs include annual average daily traffic (AADT), AASHTO road functional classification, location on the NHS or evacuation route, distance from emergency services, location of underrepresented population, equity, and so forth. 3.3 Assessment Risk assessment is based on the fundamental risk equation: the product of asset vulnerability times consequences from disruptions times threat probability. This requires a study of the con- dition of the exposed assets and their ability to resist failure, the expected losses if an asset fails, and the likelihood that an event occurs. On the other hand, resilience assessment focuses more on the post-event cycle, and how fast a system can return to normal operations after an event. Resilience is a function of a system’s robustness, resourcefulness, rapidity, and redundancy (the 4Rs) (see Appendix B for more discussion of risk and resiliency assessments). • Vulnerability Assessment. Vulnerability is the probability that an asset is negatively impacted by a threat. The probability of damage or failure can be estimated based on multiple criteria such as asset condition state, age, design standard, existing countermeasures, and the severity of threat being considered. In addition, the analysis may consider multiple damage states (such as low, moderate, severe), and the probability of reaching each damage state is assigned a single value (between 0 and 1) or qualitatively described (e.g., low, medium, or high). • Consequence Estimation. Consequences are the outcomes of an adverse event. Some of the possible consequences to be considered in the analysis include asset damage or replacement; user consequences caused by network disruption (delays); safety; and operational and envi- ronmental consequences. • Threat Probability Estimation. Determining the probability of a threat event can be qualita- tive, deterministic, or probabilistic. A qualitative analysis will involve high-level analysis and outcomes and subject matter expertise. It will have categories such as low, medium, or high. A deterministic analysis will employ either a simple frequentist approach, whereby the likeli- hood of an event occurring is the number of events that have occurred over the entire period of record, or a statistical approach, whereby the historical record is fitted to a probability distribution. However, a probabilistic approach will involve more complicated, stochastic methodologies, such as Monte Carlo simulation. • Identification of Resilience Factors. Threat likelihood, consequence, and vulnerability modeling account for the stresses that impact the system, identify the critical assets, and evaluate the vulnerability of exposed assets. Resilience factors provide context and assist decision-makers in how to best use the results of a risk and resilience assessment. AASHTO’s definition of resilience is “the ability to prepare and plan for, absorb, recover from, or more successfully adapt to adverse events.” This suggests different strategies that transportation planners can consider. Raw numbers generated from risk and resilience assessments may be of little value unless given a context of resilience metrics. • Risk and Resilience Assessments. Risk is typically defined as the product of threat likelihood times vulnerability times consequences. On the other hand, resilience assessments may also consider the post-event consequences of disruptions to the network, such as the degradation in the level of service or loss of connectivity.

14 Developing a Highway Framework to Conduct an All-Hazards Risk and Resilience Analysis 3.4 Management Finally, risk and resilience management encompasses the design and selection of mitigation and adaptation strategies. Alternative solutions take into consideration both the costs and benefits of each solution. • Risk and Resilience Strategy Selection and Evaluation. Risk management involves selecting strategies to reduce risk or enhance resilience based on a risk/resilience metric and economic analysis, such as the benefit-cost ratio, which will inform the decision-making process. • Risk and Resilience Incorporation into Decision-Making. Transportation planners should use a two-step process to optimize their investment decisions: (1) define the objectives of proposed investments, and (2) define the measures of effectiveness. For example, for a pro- posed corridor improvement project that includes adding an HOV lane, the objective could be to reduce congestion and increase mobility. The measure of effectiveness could consist of a congestion index, economic development, and vehicle usage of the new HOV lane. The risk and resilience framework for highways served as the basis for developing the over- arching roadmap and supporting RPSs. The risk and resilience framework was discussed, enhanced, and validated during stakeholder engagements.