By Thomas Harrington Jr., PhD, Vice President
From the first piece of transportation infrastructure ever built, engineers gave consideration to safety, capacity, cost of ownership, length of useful life, and resilience to known threats. What’s changed in our lifetime are the environmental conditions – the magnitude, frequency, geographic extent, and types of threats – influencing those decisions. Compounding the challenge of environmental change is the age of our infrastructure, the volume of traffic, especially in urban areas, and the fact that so much of our nation’s infrastructure is vulnerable to these new risks (as described by Rich Grady, AppGeo’s President, this past spring).
The 2nd TRB Resilience Conference (National Academy of Science, Washington DC, November 13-15th) brought together more than 300 participants from 36 states, and representatives and leaders from transportation research and leadership organizations – TRB, AASHTO, and FHWA. The conference showcased a variety of research findings, pilot projects, methodologies, questions, stories and observations. The resilience issues discussed ranged as widely as the science behind the confidence intervals on climate models, downscaling, and predictions of future events, to methods to prioritize asset management for resilience, to the existential questions of “managed retreat” – whether and how we should continue to inhabit risk-prone landscapes, and the challenges of communication about these issues.
Today, DOTs and MPOs stand at the crossroads between future assumptions about risk and current obligations to the travelling public and industry. They must manage current assets and systems, plan for the future, and communicate effectively and widely about risk, recovery and managed retreat. And they must do this with limited budgetary and other resources.
DOTs and MPOs, as stewards of our transportation infrastructure, are on the front lines of some of the trickiest and highest stakes decisions facing society today.
Below are musings on three essential questions about the rising demands on our transportation leaders and the dedicated transportation staff who confront these challenges every day.
Confidence Intervals Versus Confident Decisions
Climate scientists, data scientists, and threat assessment experts evaluate risks and event severity, frequency, and geography in terms of likelihood or probability. A powerful assumption is that past event characteristics predict future event occurrences. Statistically speaking, this concept of “stationarity” means that the mean, variance, and autocorrelation structure of data are not changing over time. The assumption that “stationarity is dead” with respect to the types of catastrophic fires, floods, storms, and other natural disasters we experience today is a game changer, making predictions more uncertain and widening confidence intervals.
Nevertheless, highway engineers, transportation planners, and DOT decision makers are tasked with translating the uncertainties, statistical probabilities and confidence intervals of climate, hazard and vulnerability modeling into concrete decisions and commitments to asset maintenance and repair/replacement in the wake of catastrophic events.
How do we take the risk profiles coming from the science community and translate them into risk assessment tools and mitigation investments, e.g., what is the high water level of the 100-year flood of the future? How do we downscale the results of global models to smaller geographies where asset management decisions need to be made?
The TRB Resilience conference provided a venue for that conversation to take place, but more communication between climate scientists and transportation engineers is needed. One attendee framed the question, which I paraphrase here: “Scientists are good at defining the probability space, but engineers have to make specific, time-bounded, geographic decisions – do I move this stretch of road, how far, and to what specification do I rebuild it?” In essence, the stationarity (underlying conditions) may change, the confidence interval may widen or narrow, but concrete has to be poured, structures built, and systems restored in the present. And it all has to be done with a limited set of current resources – dollars, technology, and personnel.
The use of mapping tools to aggregate and display asset, hazard, and risk data for transportation infrastructure was a constant theme of the conference. The power to portray risks across a transportation system – interconnected roads, bridges, culverts, tunnels, ROW, and facilities – reveals new insights. It shows interdependencies between assets, such as the discovery that the culverts have a much higher user cost (loss of use of roadways) than the owner cost (asset replacement). And in some cases, simply mapping the assets comprehensively and accurately creates opportunities for mitigation and pre-event planning (the case for mapping ROW holdings as a single statewide data layer is made persuasively by Rich Grady, AppGeo President in this blog piece).
The Geography and Economics of Risk Taking Behavior
The geography of risk is changing. DOTs are on the front line of thinking about these changing risk geographies because their assets – roads, bridges, culverts, tracks, right of ways – reach every corner of every state. These assets are costly to repair and replace, and they are increasingly in harm’s way. The default position is to maintain the current system with mitigating actions, such as hardening (or softening) structures, moving structures, and rebuilding them when damaged.
In essence, we as a society are asking the DOTs to act as the go between for local decision makers and the state and federal government. Legislators, local zoning boards, planners, developers, individuals, and businesses typically have the power to determine where and how we inhabit the landscape; they are, in essence, defining the geography of risk taking. In a post-catastrophe setting, state and federal governments are asked to provide the resources to cover the cost of restoring transportation system viability and ensuring public safety. In a pre-catastrophe setting, they must allocate scarce resources to reduce vulnerabilities, taking the extent and services of the current transportation system, and the expansion of human settlement, as a given.
The changing nature and geography of risk is, in part, a communication issue and, in part, a question of economics. From an economics point of view, for example, incentives to take risks are not balanced by the disincentives. For example, there is an asymmetry that occurs when one group gets to make bets (take risks), such as private sector land use or local government zoning, that other groups have to cover, such as the taxpayer through state or federal government funding for recovery and rebuilding.
In essence, we as a society are asking the DOTs to act as the go between for local decision makers and the state and federal governments.
How do DOTs communicate risk to those taking risks? Do we need a new vocabulary? How do we all get on the same page so that we are not rewarding risky behaviors at the local level of government and by the private sector? Are we, as humans, able to fully appreciate risk at the scale and pace at which the environment is changing?
There is a key role for geographers and map-makers to re-represent the landscapes we inhabit to help us all “see” the changing risk profiles, and respond ahead of time. Which brings us to the last topic: Managed Retreat.
Managed Retreat: The New Normal?
Decisions made at a local level by planners, zoning boards, developers, investors, and insurers define the way individuals and businesses occupy the landscape. Where people live and work establishes the need for utilities and transportation assets to follow and serve them. It is no surprise that humans raise their risk profile when they inhabit barrier islands, coastal areas, riversides, low-lying flood prone land, steep slopes, etc. But under the “new normal,” what was once considered safe ground may no longer be viable without mitigation, especially with regard to transportation systems that traverse hazards to connect places.
DOTs and MPOs are responsible for maintaining the transportation systems that have been built in the past to serve a population distributed across the land in a pattern that creates new vulnerability and risk in today’s changed environment. They are tasked with being responsive to the inhabited landscape, no matter how risky or compromised those locations might be or become.
In the near future, some transportation infrastructure may not be replaced. Insurance coverage may shrink. Compromised or high risk locations may not be served. And formerly safe spaces may be cut off from the transportation systems that can no longer serve them under the new normal. DOTs have a lot of responsibility for orchestrating this “managed retreat”. They manage and control the transportation planning process. They make trade offs between available resources and asset investments. But they must also do this in concert with local government decision makers, the travelling public and businesses.
What are the rules that will guide the managed retreat?
DOTs and MPOs, as stewards of our transportation infrastructure, are on the front lines of some of the trickiest and highest stakes decisions facing society today. Support is helpful. The scientific community can help translate risk profiles toward concrete decisions and guidelines. Local government, investors, insurers, businesses, and planners have the ability to reduce risk-taking behavior in human settlement patterns. Economists can devise strategies to help align incentives to reduce risk across levels of government and the public and private sectors. Communication experts can help promote understanding and acceptance of the new non-stationary environmental reality, to promote the necessary individual and societal adjustments. Conferences, like TRB Resilience, play a key role in bringing these communities together, and these challenges into clearer view, by providing examples and hope for a way forward.