Resiliency: The result of agencies taking appropriate action(s) to ensure that a society can continue to function effectively after a significant event or in response to a long-term change of conditions.
There is a heightened interest in ensuring the long-term resiliency of communities. Public agencies in the United States, particularly those in the most vulnerable areas, are paying closer attention to the impacts and risks posed by climate change, severe weather, and other natural disasters. They are focusing increased attention on questions of resiliency in the face of threats ranging from coastal sea level rise and storm surge to inland flooding and tornadic winds; from heat waves and drought conditions to dust storms and forest fires; from the slower but no less impactful effects of long-term climate change to the more immediate impacts of extreme weather and naturally occurring disasters.
Some areas (the New York region, Vermont, Colorado, coastal Louisiana and others) are still recovering from specific events that have reshaped entire communities and created a much heightened awareness of the vital importance of infrastructure to ensure long-term community resiliency. In California and Texas, off-the-charts weather conditions have caused many to rethink the assumptions that were the foundation for future-oriented planning, and to consider designing resilience into the infrastructure they depend upon. These realities are the same around the globe where significant weather events and longer-term climatic changes are reshaping approaches to a more resilient built environment.
While professionals seek to apply existing and new data-driven tools to identify the most appropriate responses to a changing environment, the entire resiliency field is experiencing rapid development, spurred by the dearth of accepted and approved technical approaches that incorporate future risk into planning and design.
It is also a reality of resiliency, looking forward to the future, that there are fairly large uncertainties associated with the likelihood of different system conditions occurring given the range of potential climate-related impacts. Any approach that addresses resiliency needs to therefore be based on a few principles that can help guide agency processes that recognize these uncertainties.
Assessing the implications of asset failure
The methods used to assess the implications of asset failure, in terms of potential loss to a community or agency, need to address the impact of such losses in ways that rarely, if ever, drove decision-making in the past. These methods need to explicitly include the quantifiable impacts to economic vitality, natural and environmental resources, and quality of life. The long-term effects of recent extreme weather events extended beyond those most immediate and observable, suggesting that such broader impacts need to be an explicit part of resiliency planning for all projects moving forward.
Risk-based approaches to resiliency will vary by the contexts and character of communities, and by the relative importance of assets serving these communities. This must be considered when tailoring a risk assessment approach for particular projects. Tools exist that do this for transportation-related infrastructure, and other tools are emerging that better define and predict the broader economic, social, and environmental benefits of resiliency-related transportation infrastructure investment. Combining engineering knowledge with economic values of benefit or loss facilitates the quantification of risk. It is a useful direction in which resiliency planning is heading.
Incorporating uncertainties into approaches
The range of projections of future climate conditions represents a significant challenge to resiliency planning. Disparities in forecasted sea level rise are well-known. Similar uncertainties are inherent in projections of other climactic conditions, extreme weather, and natural events. However, projections, when appropriately utilized, can provide a means to bound the range of future potential impacts (example – establish high, medium, and low potential sea level values). In areas where this range indicates significant potential effect, more sophisticated approaches (such as Monte Carlo simulations) provide a way to understand and address the implications of these uncertainties on crucial decisions that need to be made.
The use of these projections must recognize and reflect the inherent underlying uncertainties that stem from two key factors.
- The first is variability in future projections that stem from differing assumptions on future potential conditions (for example - greenhouse gas emissions scenarios), and
- The second reflects the inherent variability and uncertainty of the model outcomes themselves.
This broad range of uncertainty represents a key consideration in using future projected data and applying modeled future scenarios toward the goal of effective decision-making. Practitioners must incorporate this uncertainty into planning and design in ways that are rarely considered or applied in current practice.
Hurricane Sandy (also known as “Superstorm Sandy”) was a catastrophic event for the New York metropolitan region in October 2012 resulting in an estimated U.S. $700 billion in damage. It devastated neighborhoods, coastlines, and critical infrastructure throughout the NY region and highlighted the reality that many cities are unprepared for extreme weather events as they have not fully defined the broader implications of
Planning for Resiliency
In sum, resiliency planning for better informed engineering and agency resource allocation is evolving rapidly and changing the way we develop and implement infrastructure plans and projects. While broad principles apply, there is currently no single accepted solution. Each context calls for a tailored approach. New methods and data sources are emerging for quantifying and incorporating a broader range of economic, environmental, and quality of life factors. But at the same time, significant questions remain about the variability of data and the forecasts which they influence.
In the end, even with state-of-the-art approaches to resiliency planning and design, there is no substitute for good judgment drawn from a rapidly expanding body of knowledge – a body of knowledge reflected in this volume by the array of individual articles by WSP | Parsons Brinckerhoff colleagues.
The articles that follow, based on leading edge thinking and professional experience, include approaches that reflect the key principles and practices that build resiliency. They are written by professionals who represent a range of backgrounds and professional interests and who provide varying perspectives on resilience - perspectives that consider risk, vulnerability, failure, and emerging changes in analysis and design methods.