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Transportation, Climate Change & Extreme Weather Vulnerability Assessment Webinar Series - May 16, 2013

Session 1:

May 16, 2013 3:00-4:30 PM EDT


Available at:

(Note: a transcript is also being posted with this summary)


The presenters included: Rebecca Lupes and Rob Kafalenos of FHWA Office of Natural Environment, Mike Flood of Parsons Brinckerhoff, and Joel Smith of Stratus Consulting, Inc.

Session Overview:

Session 1 of the Webinar Series introduced the concept of the vulnerability assessment - a key first step for climate change planning that provides understanding of how climate change will affect a transportation network. The presenters began with an introduction to the Climate Change and Extreme Weather Vulnerability Assessment Framework, developed in 2012. The Federal Highway Administration (FHWA) modeled this document largely on findings from five pilot projects conducted by partner MPOs and State DOTs in 2010-11, as well as the on-going Gulf Coast II project. This Webinar Series follows the structure of the framework and begins with an explanation of the key steps involved in designing and implementing a vulnerability assessment: The first session focused on defining objectives, determining asset criticality, and developing climate input.

Introduction to Vulnerability Assessment Framework, Becky Lupes

FHWA's Climate Change and Extreme Weather Vulnerability Assessment Framework serves as a suggested organizing mechanism for transportation agencies planning to conduct a climate change or extreme weather event vulnerability assessment. The framework is comprised of three main components: defining scope, assessing vulnerability, and integrating results into decision making. The first component, defining project scope, includes defining objectives, identifying relevant assets, and assessing climate variables. Objectives, assets, and climate variables vary widely from case to case. The second component, assessing vulnerability, requires assessing climate inputs, asset data, vulnerabilities, and risk. The third component, integrating vulnerability into decisionmaking, involves identifying and prioritizing adaptation options and incorporating assessment results into programs and processes.

Assessing Criticality of the Transportation System, Michael Flood

Defining "criticality" is an essential aspect of developing the objectives and scope of a vulnerability assessment. The term "criticality" can refer either to assets that are at risk or assets that are of critical importance. Clearly defining critical systems is important because it allows planners to focus limited study resources for vulnerability assessments and set informed policies on risk tolerance.

The next task in a vulnerability assessment is selecting transportation assets to study. Three methodologies to determine critical transportation systems are the desktop method, the stakeholder method, and the hybrid approach. The desktop method analyzes data to develop a ranking of criticality across the network. The disadvantage of this method is that it fails to reflect local input and it may lack data from private transportation entities, such as ports. The stakeholder method initiates a discussion with individuals familiar with the transportation network. The disadvantage of this method is that it may be subject to personal preference and that the facilitation of the stakeholder discussion may impact results. Under the hybrid approach, planners apply a data-driven methodology, then involve stakeholders to make final determinations.

The Gulf Coast II study used a hybrid approach to identify a subset of the transportation network on which to perform a vulnerability assessment and to identify adaptation measures. The assessment considered three key categories of infrastructure: socio-economic (e.g. community connections), operational (e.g. classification and usage), and health and safety (e.g. evacuation routes and access to hospital facilities). With these considerations in mind, planners delineated important assets, developed a scoring summary based on available data, and applied engineering judgment to fill data gaps. Sharing these ratings and scores with local stakeholders can then ensure that the assessment captures the concerns of the region.

Use of Climate Change Information in Assessing Vulnerability of Your Transportation System, Joel Smith

One aspect of assessing vulnerability is obtaining and developing information on projected changes in climate and extreme weather events. The challenge of using information on climate change is that it is difficult to accurately forecast the exact changes in climate over time. Two options for assessing vulnerability include the top-down approach and the bottom-up approach. The top-down method is a scenario approach that uses outputs from climate models to create a plausible combination of conditions. The scenarios reflect a range of projected changes in greenhouse gas emissions and concentrations, different changes in the Earth's climate, and different changes in regional climate. The advantage of this method is it allows decisionmakers to visualize expected scenarios and identify outcomes that may escape the bottom-up approach. The bottom-up method is a threshold approach that uses outputs from models to address customized climate concerns relevant to the transportation assets being studied such as extreme heat, flooding, or storm surges. First we look at current exceedences of thresholds, and then examine how conditions could change under different scenarios for the future. The advantage of this approach is that it focuses on the individual transportation asset or network in question rather than the output from a given model. Another advantage of this approach is that it provides planners a sense of when critical thresholds are likely to be crossed. With either approach, the goal is to understand how a particular transportation system could be vulnerable to long-term changes in climate and climate variability in order to begin working on contingency planning and adaptation measures to reduce risks.

Both approaches to assessing changes in climate rely on models used to predict the impact of climate change. These models fall into two categories. General Circulation Models (GCMs) divide the earth's atmosphere into large grids and estimate a uniform climate for a given grid. Regional Climate Models (RCMs) are based on GCMs, but have smaller grid boxes (approximately 30 miles by 30 miles) and are better at capturing local features like lakes, mountains, and coastlines. The problem with both models is that they all produce differing predictions of temperature and precipitation change; there are over 40 models and each may demonstrate different patterns. RCMs may exacerbate the differences between models, as they produce more granular predictions based on divergent inputs from GCMs.

Gulf Coast 2 Sea Level Rise and Storm Surge Projections, Rob Kafalenos

In developing the Vulnerability Assessment Framework, FHWA drew from the Gulf Coast Study Phase 2 in Mobile, AL as an example of a metropolitan-scale vulnerability assessment. Phase I of the study provided an overview of climate change impacts on transportation infrastructure in central Gulf Coast. The Phase 2 study is ongoing, and is focused on Mobile, Alabama. The first two tasks in Phase 2 focused on developing information that will be used in the vulnerability assessment. In Task 1, the critical transportation assets in Mobile were identified. In Task 2, projections of climate effects were identified and used to assess infrastructure exposure. This process included looking at global and local sea level rise (SLR) and storm surge scenarios. For this study, FHWA developed local SLR scenarios based on historic rates of local land movement (including subsidence) and global SLR. Next, FHWA identified the critical assets that would be inundated under each of the three SLR scenarios. FHWA also developed 11 storm surge scenarios based on data from historic hurricanes with projected modifications to SLR, , the track of the storms, wind speeds and pressure.

Additional tasks under the Phase 2 study, which are currently underway, involve assessing the vulnerability of the most critical transportation assets and developing transferable risk management tools for the future use of State DOTs.

Updated: 03/27/2014
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