Bracing for Hard Times Ahead
What is FHWA doing to prepare the country’s transportation system for climate change? Here are tools for assessing and improving the Nation’s readiness and resilience.
Although strategies for adapting to weather-related natural hazards should be nothing new to transportation officials, the increasingly alarming information connected to climate change calls for a heightened level of urgency. Rising sea levels and air temperatures are among the disturbing trends.
The rate of change is expected to increase in the coming decades. In 2014, the National Climate Assessment projected that sea levels will rise as much as 4 feet (1.2 meters) by 2100. Temperatures could rise by 4 degrees Fahrenheit (°F) (2.2 degrees Celsius, °C) in the next few decades and 10 °F (5.5 °C) by the end of the century, depending on emissions of greenhouse gases. The frequency of the strongest hurricanes is expected to increase by the end of the century as well.
The transportation system and its individual assets already are designed to withstand a range of environmental conditions, including extreme weather events. However, climate change adds stressors, such as more frequent and severe storms, that are not fully addressed in current planning and design processes.
Impacts resulting from climate change and extreme weather threaten the considerable Federal, State, and local investments in transportation infrastructure. They also jeopardize the transportation community’s shared goals of improved safety, system reliability, and asset management.
As Mike Culp, leader of the Sustainable Transport and Climate Change Team at the Federal Highway Administration (FHWA), notes, “The only way we can preserve the state of good repair of our transportation system is to plan for future climate and incorporate certain types of designs or treatments that will help protect the system in the future.”
Because of the myriad challenges arising from climate change, FHWA has been studying the impacts on transportation for more than a decade. As a result, FHWA is spearheading a number of activities to help its partners--State departments of transportation (DOTs) and metropolitan planning organizations (MPOs)--assess their vulnerabilities and develop policies and strategies to address climate change and extreme weather events by building a more resilient transportation system.
Efforts include developing tools to support activities at the systems level, such as regional and statewide planning and asset management to promote resiliency. The goal is for the transportation network to meet current and future environmental conditions by taking into account climate change risks in all relevant transportation decisions. Other tools support project-level activities, including environmental reviews, preliminary engineering, design, construction, operations and maintenance, and rehabilitation and reconstruction activities.
To date, various initiatives are underway, including two key efforts: a U.S. Department of Transportation (USDOT) Gulf Coast Study and pilot studies of climate resiliency. The latter resulted in the development of a framework for assessing vulnerability to climate change.
The Gulf Coast Study
The first phase of the Gulf Coast Study, completed in 2008 and managed by FHWA in partnership with the U.S. Geological Survey, sought to identify potential vulnerabilities across the coastal region from Houston, TX, to Mobile, AL. The second phase includes development of adaptation options for key, vulnerable transportation facilities in the region.
The Effects of Climate Change
Climate change impacts of concern include rising sea levels, which can affect broad areas and make it difficult to maintain roads and highways. Low-lying and subsiding areas along portions of the Gulf and Atlantic coasts are particularly vulnerable to future sea level rise. In general, concerns include the following:
The project consists of four main tasks: (1) identification of transportation infrastructure considered critical to Mobile, (2) development of information on climate projections necessary to inform transportation decisionmaking at the engineering and operations levels, (3) analysis of vulnerability across the range of critical assets for each transportation mode represented, and (4) engineering analysis and development of adaptation options for 11 assets or transportation functions.
Pilot Studies of Resiliency
In addition to the Gulf Coast Study, FHWA has sponsored two rounds of pilot studies that helped the agency develop a framework for the assessment of risk and vulnerability to climate change. The first set of five pilot projects was conducted in 2010 and 2011 by the Metropolitan Transportation Commission in San Francisco, CA, in conjunction with the Bay Area Conservation and Development Commission; the OahuMPO in Hawaii; the New Jersey DOT, together with three New Jersey MPOs; the Virginia DOT; and the Washington State DOT. FHWA used the results of the pilots and other work to develop a Climate Change & Extreme Weather Vulnerability Assessment Framework (FHWA-HEP-13-005).
Although FHWA learned a great deal from the five pilot projects, the following additional needs emerged: paying greater attention to inland areas and moving beyond vulnerability to focus on solutions. To address these needs, FHWA selected 19 additional pilots from a large pool of submissions in 2013. The pilots are scheduled to be completed by early 2015.
Many of the pilots are focused on adaptation, from both programmatic and engineering standpoints. The projects span a range of impacts and cover a broad geographic area. The work of the pilot projects will help further the state of practice in the emerging area of resilience to climate change. After the 19 pilot reports are completed, links to them will be available on the FHWA Climate Change Adaptation site at www.fhwa.dot.gov/environment/climate_change/adaptation.
Tools and Guides
The second phase of the Gulf Coast effort and the five initial pilot projects led to the development of a suite of practical tools to help transportation organizations conduct assessments of vulnerability and develop adaptation strategies. Each of the tools, guides, and procedures is designed to simplify the analysis process.
The first of these tools is an assessment framework that outlines an overall analytical process. The framework largely draws from the experiences gathered from the five pilot projects that FHWA sponsored in 2010 and 2011. It also draws examples from USDOT’s Gulf Coast Study and work by other agencies around the country.
The other tools and procedures facilitate additional tasks, such as identifying critical assets and their sensitivity to climate effects, collecting climate information relevant to coastal and inland areas, evaluating and ranking vulnerabilities, assessing project-level vulnerabilities, and developing adaptation options.
The Climate Change & Extreme Weather Vulnerability Assessment Framework is a guide for transportation agencies interested in evaluating their vulnerability to climate change and extreme weather events. It provides a set of key steps to conduct vulnerability assessments and uses in-practice examples to demonstrate a variety of ways to gather and process information.
Climate Change and Extreme Weather Vulnerability Assessment Framework
Sandy Salisbury, manager of the Roadside and Site Development program at the Washington State DOT, says, “It’s important to do a vulnerability and risk assessment because things are changing. We need to know where we have weaknesses in a system, and we need to be able to look ahead and prioritize where to do work based on what’s vulnerable and what’s critical.”
Climate Resiliency Tools and Guides: An Overview
FHWA has developed, or is in the process of developing, the following products related to climate change. All of the tools will be available on the FHWA Web site at www.fhwa.dot.gov/environment/adaptationframework.
Vulnerability Assessment Framework. The Climate Change & Extreme Weather Vulnerability Assessment Framework (completed by FHWA in 2012) is intended for transportation agencies conducting vulnerability assessments. The tool includes discussion, resources, and in-practice examples of the major tasks involved in assessing vulnerability to climate change.
Vulnerability Assessment Scoring Tool (VAST). This Excel®-based tool (with macro-driven user interface) enables users to design and structure an indicator-based vulnerability assessment. Once FHWA completes VAST in the fall of 2014, State DOTs will be able to use it to create a relative vulnerability score for each asset evaluated.
CMIP Climate Data Processing Tool. This large Excel® file processes raw climate data, which users download from a third-party site. Outputs are projected temperature and precipitation changes in a local area. The tool, which was developed by FHWA, provides a relatively quick and easy way for users to determine the potential magnitude of certain changes in their area. The tool will also be available on FHWA’s climate Web site, as will the following FHWA tools:
Procedures for Analyzing Coastal Processes. These procedures and examples provide information on how to develop scenarios for future sea level rise and coastal storms and how to model the resulting impacts.
Engineering Analyses: An 11-Step Process. This assessment process provides a method to analyze the vulnerability of a particular road link, bridge, or other facility to projected changes in climate and develop, analyze, and ultimately select adaptation options.
Assessing Criticality in Transportation Adaptation Planning. This guide helps transportation agencies determine how to focus their vulnerability assessments on the most critical components.
Transportation Climate Change Sensitivity Matrix. This spreadsheet documents how different climate stressors affect several types of transportation infrastructure. The tool contains a macro-based user interface that enables users to generate reports related to specific stressor-asset combinations according to their needs.
A companion Web site, www.fhwa.dot.gov/environment/adaptationframework, for the assessment framework includes links to additional resources, tools for conducting the assessments, and video interviews with transportation professionals who have undertaken some of the steps.
For the most part, the framework is limited to assessing the vulnerability of the transportation system as opposed to evaluating adaptation options. In the future, FHWA plans to update and expand the resource into a Climate Change Resilience Frame-work with the results of several studies currently underway or recently completed, including the Gulf Coast Study’s engineering assessments, the 19 climate resilience pilots, and the Hurricane Sandy Follow-up and Vulnerability Assessment and Adaptation Analysis project.
Vulnerability Assessment Scoring Tool (VAST)
Among the results to date, FHWA has developed VAST, an Excel ® -based tool, to provide a structured framework for conducting an indicator-based scoring process for State DOTs, MPOs, and other organizations to assess vulnerability to climate change. In other words, VAST helps a user derive a vulnerability score for any given transportation asset at any scale. A road segment, a bridge, or an airport could all be examples of assets.
The user calculates the vulnerability score as a function of exposure, sensitivity, and adaptive capacity. The score is derived from a series of indicators. For instance, the elevation of the deck of a coastal bridge could be an indicator of the structure’s sensitivity to sea level rise. Similarly, pavement mix and traffic load could be used as indicators of a road segment’s susceptibility to high temperatures.
|Vulnerability Assessment Scoring Tool|
The VAST tool guides users through several steps: (1) choosing relevant climate stressors to evaluate; (2) selecting exposure, sensitivity, and adaptive capacity indicators; (3) collecting data about climate and assets; (4) developing scoring approaches to convert raw data into scores on a scale of 1 to 4; and (5) reviewing the vulnerabilities identified in the tool. The result is a set of numerical scores that can be used to rank assets by vulnerability.
The tool is designed to be highly flexible. Users can choose from a set of indicators or make their own, and adjust the scoring system based on a variety of factors, such as expert judgment, stakeholder input, or established thresholds. In addition, VAST is designed to be a transparent tool that helps users to decide which factors are most important and then to apply those factors systematically to the data collected.
It is important to understand what VAST does and does not do. VAST does provide a structure for users to enter data they have collected and interpret that data to better understand vulnerabilities in their system. VAST does not provide “default” information about particular assets or their vulnerability; instead, the tool relies on input about assets and climate provided by the user.
CMIP Climate Data Processing Tool
The World Climate Research Programme, sponsored by the United Nations, developed the Coupled Model Intercomparison Project (CMIP) as a standard experimental protocol for studying the output of climate scientists’ models that couple the general circulation of the atmosphere and that of the oceans. The CMIP Climate Data Processing Tool is Excel®-based and uses readily available temperature and precipitation projections to calculate variables that can be used to assess the vulnerabilities of transportation infrastructure.
These variables include temperature and precipitation thresholds similar to those used in the second phase of the Gulf Coast Study. Those thresholds are relevant to the design, operation, and maintenance of transportation infrastructure. Examples include the following:
- Average number of days above 95 oF (35 oC), 100 oF (38 oC), 105 oF (41 oC), and 110 oF (43 oC)
- Highest 4- or 7-day average summer temperature
- Largest 3-day rainfall event per season
- Very heavy 24-hour precipitation amount
Climate Projection for a Sample Grid Cell
|Click column headings for additional info||Baseline (1970–1999)||Mid-Century (2030–2059)|
|Observed Value||Modeled Value||Projected Value||Change from Baseline||% Change from Observed||Model Uncertainty Range (95% Confidence Interval)|
|Average Annual Mean Temperature||76.1℉||75.5℉||77.6℉||1.6℉||0%||77.4℉||77.9℉|
|Average Annual Maximum Temperature||83.7℉||83.5℉||85.3℉||1.5℉||0%||85.0℉||85.5℉|
|Average Annual Minimum Temperature||68.4℉||67.4℉||70.0℉||1.6℉||0%||69.8℉||70.2℉|
|Annual Extreme Heat|
|Hottest Temperature of the Year||94.6℉||93.0℉||97.4℉||2.9℉||1%||96.9℉||97.9℉|
|“Very Hot” Day Temperature (Very Hot defined as 95th Percentile Temp)||91.7℉||90.9℉||93.9℉||2.2℉||0%||93.5℉||94.3℉|
|“Extremely Hot” Day Temperature (Extremely Hot defined as 99th Percentile Temp)||93.8℉||92.2℉||96.2℉||2.4℉||0%||95.8℉||96.6℉|
|Average Number of Days per Year Above Baseline “Very Hot” Temperature (91.7 °F)||18.3 days||18.3 days||75.6 days||57.3 days||314%||66.4 days||84.7 days|
|Average Number of Days per Year Above Baseline “Extremely Hot” Temperature (93.8 °F)||3.7 days||3.7 days||43.0 days||39.4 days||1,074%||33.2 days||52.9 days|
|Average Number of Days per Year above 95 °F||1.3 days||0.0 days||6.0 days||4.8 days||375%||3.5 days||8.5 days|
The CMIP tool includes instructions for how to download the data and calculate the projections for up to four grid cells. Climate scientists divide the earth’s surface into grid cells, then calculate projections of future conditions for those cells, and average them for two future time periods--midcentury and end-of-century. Although climate models can produce values down to as short as a day, it is important to consider average values over a minimum of 20 years when projecting future climate conditions, because climate is defined as the average of weather over a minimum of several decades.
The data are housed on a site hosted by the U.S. Bureau of Reclamation and other organizations and Federal agencies. The site hosts two versions. The first is based on CMIP phase 3 projections used in the United Nations’ Intergovernmental Panel on Climate Change’s (IPCC) Fourth Assessment Report (2007) and Global Climate Change Impact in the United States (2009). The other version relies on the CMIP phase 5 dataset from the National Climate Assessment (2014) and the IPCC’s Fifth Assessment Report (2013–14).
The CMIP datasets include both historic, monitored information for daily minimum and maximum temperature and daily precipitation, and projections of these values from a range of scenarios for greenhouse gas emissions. The CMIP projections statistically downscale projections from global climate models, which are produced at a scale of roughly 100 kilometers by 100 kilometers or more, to a spatial resolution equivalent to roughly 7.5 miles (12 kilometers) by 7.5 miles or 56 square miles (145 square kilometers).
|This screen shot from FHWA’s VAST tool shows the number of assets (in this case, roads) in various scenarios with vulnerability scores at low, moderate, or high levels, or no exposure.|
The downscaling process relies on relationships evident in past precipitation and temperature data between the two scales (and assumes that they will remain constant over time). Climate scientists apply those statistical relationships to future global climate model projections to develop projections at the smaller scale. (For more information, see the two reports produced as part of Gulf Coast Study phase 2, task 2, available at www.fhwa.dot.gov/environment/climate_change/adaptation/ongoing_and_current_research/gulf_coast_study/phase2_task2.)
Rob Graff, manager of the Office of Energy and Climate Change Initiatives at the Delaware Valley Regional Planning Commission (DVRPC), notes that the tools have been designed with the end user in mind. He says, “The CMIP Climate Data Processing Tool enables the user to quickly access and process the full range of climate projections available from the CMIP database, which can save considerable time and money for an MPO or other users.”
Procedures for Analyzing Coastal Processes
Regarding coastal processes related to climate change, such as local sea level rise and storm surge and wave action caused by coastal storms, FHWA provides procedures and guidance via two major sources: the second phase of the Gulf Coast project in Mobile and a new hydraulic engineering circular, Highways in the Coastal Environment: Assessing Extreme Events (HEC-25 Volume 2).
The second task of the Gulf Coast phase 2 study examined climate-related coastal stressors using a scenario approach that looked at combinations of various sea level rises with a select group of coastal storms (hurricanes). The scenarios were tied to sea level increases of just under 1 foot (0.3 meter) in 2050, and moderate and high projections of almost 2.5 feet (0.75 meter) and more than 6.5 feet (2 meters), respectively, in 2100. Although sea level rise may be relatively small, it can amplify the impacts of coastal storm surge and wave action.
The scenarios were based on two historical storms that damaged Mobile: Hurricanes Katrina in 2005 and Georges in 1998. Because impacts are sensitive to parameters such as sea level, wind speed, barometric pressure, and storm track, the researchers adjusted the variables in the historical storms to look at a range of plausible “what if” scenarios of inundation and damage.
Although the researchers assigned no probabilities of occurrence to the scenarios, the analysis provides a range of calculated degrees of impact to guide planning by a community. Given the large amount of uncertainty associated with predicting when and to what magnitude climate change will affect coastal processes, many communities are choosing to select one or two future scenarios to plan for and will likely revisit these in the near future as trends emerge more clearly and climate science improves.
HEC-25 Volume 2, released October 2014, provides technical guidance on a national scope for assessing the vulnerability of coastal highways to extreme events and climate change. The document focuses on quantifying exposure to sea level rise, storm surge, and waves when considering climate change.
It identifies critical coastal processes and unique phenomena (for example, tides, tsunamis, bluff erosion) specific to regional shorelines of the United States, including the Great Lakes. It also provides an example of how to project future sea level rise for any location tied to tidal gauges around the country.
Depending on the resources available to an individual community and the degree of precision desired, local decisionmakers might choose any of three suggested levels of effort for conducting vulnerability assessments. The document provides case studies to illustrate those levels of effort. The first level involves the use of existing floodplain maps with no computer modeling. The second level includes computer modeling of surge and wave fields for specified storm and climate change scenarios. Level 3 is similar to level 2 but characterizes exposure in terms of probability and risk, and assigns unique probabilities to the scenarios.
Jurisdictions may also benefit from the brief discussion of adaptation options, from protection with hard structural solutions and soft nonstructural solutions, to relocation and strategies of planned retreat.
Engineering Analyses: An 11-Step Process
The FHWA researchers applied the following 11-step process in engineering analyses in the Gulf Coast Study. In addition, they are using similar analytical frameworks in two other FHWA studies: Hurricane Sandy Follow-up and Vulnerability Assessment and Adaptation Analysis (expected publication 2015) and the Transportation Engineering Approaches to Climate Resiliency (expected publication 2016), as well as in some of the ongoing pilot projects that will be completed in 2015.
- Describe the site context, including location-specific details, such as surrounding land uses, population, and economic activities; performance characteristics of the transportation network; environmental resources; and long-term transportation and land use plans. Also include the function(s) of the transportation facilities and whether they take climate change impacts into account.
- Describe the existing or proposed facility, including location, functional purpose, design type, dimensions, elevations, design life, age, and condition.
- Identify climate stressors that might impact infrastructure components, such as variables that would typically be considered in the planning and design of the subject facility (for example, precipitation, temperature, sea level, storms).
- Decide on climate scenarios and determine the magnitude of the changes. Describe the climate model projections used to determine whether and how much each of the variables of concern might change in the future.
- Assess the performance of the existing or proposed facility today under current climate conditions and in the future under each of the possible future climate scenarios selected in step 4.
- Identify adaptation option(s). Describe potential planning or design-oriented options that could be used to address climate risks to the facility.
- Assess the performance of the adaptation option(s) under each potential climate change scenario selected in step 4. This analysis is similar to step 5, except that it is performed on the adaptation options applied to the existing facility as opposed to the existing facility without those adaptations, or in the case of new facilities, the standard design without adaptations.
- Conduct an economic analysis. Evaluate how the benefits of undertaking a given adaptation option, defined as the costs avoided because of the adaptation, compare to its incremental costs under each of the possible future scenarios developed in step 4.
- Evaluate additional decisionmaking considerations, including other (nonengineering, noneconomic) factors that should be considered before a final decision is reached.
- Select a course of action after considering both economic and noneconomic factors, weighing all of the information presented.
- Plan and conduct ongoing activities, including monitoring, using tools such as facility management plans.
- Next Steps
In addition to these tools, FHWA has developed two others to guide the user in analyzing the criticality and sensitivity of transportation facilities. The criticality tool--Assessing Criticality in Transportation Adaptation Planning--provides information on how to design and focus an assessment of criticality to meet the needs of the ultimate user or audience. It also summarizes the approach used in the Gulf Coast 2 study and several of the adaptation pilot studies, as well as the range of criteria used.
The Transportation Climate Change Sensitivity Matrix is a tool that helps the user understand how different asset types across transportation modes can be affected by a range of climate stressors. DVRPC’s Graff says, “The Transportation Climate Change Sensitivity Matrix is an excellent compendium of information that summarizes the climate stressor/infrastructure relationships for multiple climate stressors and types of infrastructure. It is a great tool for helping planners and engineers begin to talk about potential vulnerabilities.”
Many of the tools and guides resulted from projects conducted by FHWA, USDOT, and their partners. In addition, FHWA has a range of ongoing activities designed to provide further information to help transportation agencies understand the risks posed by future extreme weather events and climate change, and provide guidance on how to counter these risks. These ongoing activities include the second round of 19 climate resilience pilots, the Hurricane Sandy Follow-up and Vulnerability Assessment and Adaptation Analysis, and a new effort focused on project-level engineering analyses.
Robert Kafalenos is an environmental protection specialist on FHWA’s Sustainable Transport and Climate Change Team in the Office of Planning, Environment & Realty. He holds a bachelor’s degree in Chinese language and literature from the University of Kansas and a master’s degree in resource economics and policy from Duke University.
Robert Hyman is also an environmental protection specialist on the same FHWA team. He holds a bachelor’s degree in earth and planetary sciences from Harvard University and master’s degrees in civil and environmental engineering and in technology and policy from the Massachusetts Institute of Technology.
Rebecca Lupes is another environmental protection specialist on the same FHWA team. She holds a bachelor’s degree in economics from Cornell University and a master’s degree in resource economics and policy from Duke University. She manages FHWA’s climate resilience pilot effort.
Brian Beucler is a hydraulic engineer with FHWA’s Office of Bridges and Structures. He holds a bachelor’s degree in civil engineering from the University of Virginia and a master’s degree in civil and environmental engineering from The George Washington University.
For more information, please visit the FHWA adaptation Web site at www.fhwa.dot.gov/environment/climate_change/adaptation or contact Robert Kafalenos at 202–366–2079 or email@example.com. Or email firstname.lastname@example.org, email@example.com, or firstname.lastname@example.org.