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The Gulf Coast Study, Phase 2

Introduction

The U.S. Department of Transportation's Center for Climate Change and Environmental Forecasting is conducting a comprehensive, multi-phase study of climate change impacts on transportation in the Central Gulf Coast region. This study, formally known as Impacts of Climate Change and Variability on Transportation Systems and Infrastructure: Gulf Coast Study (hereafter, "the Gulf Coast Study"), is the first such study of its magnitude in the United States and thus represents an important benchmark in our understanding of what constitutes an effective transportation system adaptation planning effort. This report presents the findings of the first task of Phase 2 of this study-identifying critical transportation assets.

While confidence in global climate change projections has been steadily increasing over recent years, investigations into the potential impacts of projected changes on a regional scale have been scarce. The exact risks that climate change poses to transportation systems are not yet well known. As many of the nation's infrastructure components, such as rail lines, highways, bridges, and ports, are expected to last for up to 100 years, it is important that their design and long-term operations consider factors that could affect their resilience and effectiveness over their life span, such as changing environmental conditions due to climate change.

The Gulf Coast Study was initiated to better understand climate change impacts on transportation infrastructure and to identify potential adaptation strategies. This study area was selected as the study's focal point due to its dense population and complex network of transportation infrastructure, as well as its critical economic role in the import and export of oil, gas, and other goods. The study is funded under the U.S. Department of Transportation's (USDOT) Surface Transportation Environment and Planning cooperative research program, the USDOT's Center for Climate Change and Environmental Forecasting, and other USDOT offices, with FHWA managing the study for USDOT with assistance from the DOT Climate Center and individual modal administrations. The U.S. Geological Survey (USGS) has provided support for much of the climate science work.

The Gulf Coast Study includes two phases:

• Phase 1 (2008) - During Phase 1, FHWA partnered with the USGS and the U.S. Climate Change Science Program to investigate potential climate change risks and impacts on coastal ports, road, air, rail, and public transit systems in the region from Mobile, Alabama to Houston/Galveston, Texas. The study assessed likely changes in temperature and precipitation patterns, sea level rise, and increasing severity and frequency of tropical storms. The assessment concluded that storms could increase in intensity by at least 10%, hurricanes of at least Category 3 intensity are likely to increase in frequency, average annual temperatures are expected to rise by at least 2.7°F over the next fifty years, the number of days over 90°F could increase by 50%, and relative sea level rise could increase by at least a foot (and in many areas more) by 2050 raising the specter of widespread inundation. Phase 1 then explored how these changes could impact transportation systems. It found that a relative sea level rise of four feet would permanently inundate 27% of the Gulf Coast region's roads, 9% of its railways, and 72% of its ports; higher temperatures would likely lead to more rapid deterioration of infrastructure and higher maintenance costs; more intense precipitation events could overwhelm drainage systems and cause damage and delays; and increased hurricane intensity coupled with sea level rise would pose a significant threat to infrastructure.

• Phase 2 Study Area

  While Phase 1 took a broad look at the entire Central Gulf Coast region (between Houston/Galveston, Texas and Mobile, Alabama) with a 'big picture' view of the climate-related challenges facing infrastructure, the current effort in Phase 2 focuses on Mobile, Alabama. The area of the study includes Mobile County (including Dauphin Island) and the crossings of Mobile Bay to the east to landfall in Baldwin County (see Figure 1).

  "Phase 2 (currently underway) - The purpose of Phase 2 is to provide a more detailed assessment of the vulnerability of the most critical components of the transportation system to weather events and long-term changes in climate. This work is being conducted on a single metropolitan area-the Mobile, AL region (see Box)-with the intention of making the processes used in the study replicable to other areas. USDOT is conducting Phase 2 in partnership with the Mobile Metropolitan Planning Organization, part of the South Alabama Regional Planning Commission (SARPC).

Phase 2 includes the following tasks:

• Task 1: Identify critical transportation assets.
• Task 2: Develop climate information and assess sensitivity of assets to climate stressors.
• Task 3: Determine the vulnerability for key links and assets.
• Task 4: Develop and apply detailed risk management tools.
• Task 5: Coordinate with local planning authorities and the public on the process and implications of the analysis.
• Task 6: Publish and disseminate the information learned.

This report summarizes the methodology and findings of Task 1, which identified the transportation infrastructure components most critical to the Mobile region.

Figure 1: Study Area